Page 1

February 2015

From

NEWCOMER to GLOBAL

LEADER Siglent’s Rise to the Top in the Global Scope Market

Interview with Steve Barfield General Manager of Siglent

New Power Efficiency Standards Tips & Techniques for Capacitor Testing


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PS COMER V

Siglent’s Rise toCONTENTS the T of the Chinese Scope

Modern Test & Measure

and

HNIQUES

GLOBAL

irtually every type of electronic hardware incorporates capacitors, which are widely used for functions such as bypassing, coupling, filtering, and tunneling electronic circuits. However, he toglobal be useful, their regulatory environment surrounding legislation of external capacitance value,the voltage power supply efficiency and no-load power draw has rapidlycoefficient, evolved over the past rating, temperature decade since the California Energy Commission and leakage resistance must be (CEC) implemented the first mandatory

CONTENTS

apacitor TECH T REPORT Efficiency Standards for Efficiency Tips and Techniques esting STANDARDS External Power Supplies for Capacitor Testing

ADER

e V VI IV logy VI

V IV

ration nerators

companies offering advanced test equipment. In the

change again as regulators try to further reduce many of the electronics manufacturers the amount of energy consumed by external adapters. who build thempower into their products also perform someMandating of these tests quality higher averageas efficiencies in external power supplies has undoubtedly had checks. This article looks tips andpower techniques a real at impact on global consumption. However, with the benefit of a reduced draw that can simplify the process of capacitor testing. on the power grid come challenges and Based on the EasyPulse architecture,

following years, the industry has taken off, with hundreds

14

of big name companies dominating the markets—

REPORT V IV TECH New Efficiency Standards

VI

However, this method comes with some disadvantages:

• Waveforms are affected by the signal’s frequency, meaning the rising and falling edge transition time will be limited at low frequencies.

VI

• The output pulse will be limited by waveform length, so the duty cycle cannot be very small.

• Waveform data will need to be updated when changing the pulse’s frequency, edge, and width. If the waveform length is large, it needs more time to change the other parameters of the pulse.

e signals by most aveform memory ulse waveform data

in the field was Hewlett Packard—one of the only

standard in 2004. With the publication of a

Power Supplies

V IV

4

industry since the 1970s. Back then, the big player

characterized. new set ofAlthough requirements bycapacitor the United States Department of Energy (DOE) set to go into manufacturers perform these tests, effect February 2016, the landscape is set to

Efficiency Standards for External Supplies for Power External

le Cigoy, Lead Applications Engineer ey Instruments, a Tektronix Company

S

teve Barfield has been in the Test & Measure

uncertainties for the electronics industry as it

the SDG5000 and SDG800 can tries to keep up with this dynamic regulatory environment. produce low-jitter, rapid rising, and falling edge, without being affected by Original Equipment Manufacturers (OEMs) frequency or extreme duty cycle. who design The external power supplies into their products must continue to monitor the pulse transition time can be adjusted latest regulations to ensure that they are in over a larger range, and fine resolution. compliance in each region where their product sold. The goal of this paper is to provide The EasyPulse method is isillustrated an up-to-date summary of the most current in the following block diagram: regulations worldwide.

each offering their own spin on these classic devices. While customers tend to go with the brands they trust,

for ExternalBarfield Power feels Supplies there should be more emphasis on overall engineering experience: better specs, better support, and

Siglent’s EasyPulse technology comes with significant advantages. For one, it can output rapid rising and falling edges (6ns), even at very low frequencies (less than 1Hz); and the pulse width can be 12ns under low frequency, with very long or short duty cycles. Parameter changes such as pulse can be easily and immediately changed without updating any waveform data and the edge and pulse width can be n tio adjusted over wide ranges. egula

24

lower price. This is why Barfield joined Siglent, a relatively 16

INDUSTRY INTERVIEW equipment company that is making its mark in s new test pplie ry 20

a Febru ffect e e k ta set to

s Su erFrom dard To solve these problems, Siglent iew with Steve Barfield w the field.to EEWeb with Barfield about some of the o eform corresponding Newcomer Leader I stan spoke P l l VGlobal e innovated a new algorithm for pulse a v e n L r and width of this w e e t generation, called EasyPulse technology, en eral Manager of Siglent to th General tains low jitter. This or Exand Steve Barfield, of Siglent fSDG5000 Siglent Manager differentiate themselves from which is built in the new up ways 2004 familiar s e more d r a befor ock diagram (figure 1.) SDG800 series waveform generators. t d e r s n 4 ta ere 00 C’s 2 rds wled to explosive growth tarystandahas brands and how this ncy S napproach e he CE u i t l c m o y o r V andato fr Effi path

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TECH REPORT

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3u


Modern Test & Measure

TIPS and

TECHNIQUES for

Capacitor Testing By Dale Cigoy, Lead Applications Engineer Keithley Instruments, a Tektronix Company

4


TECH REPORT

V

irtually every type of electronic hardware incorporates capacitors, which are widely used for functions such as bypassing, coupling, filtering, and tunneling electronic circuits. However, to be useful, their capacitance value, voltage rating, temperature coefficient, and leakage resistance must be characterized. Although capacitor manufacturers perform these tests, many of the electronics manufacturers who build them into their products also perform some of these tests as quality checks. This article looks at tips and techniques that can simplify the process of capacitor testing.

5


Modern Test & Measure Capacitor Basics A capacitor is somewhat like a battery in that they both store electrical energy. Inside a battery, chemical reactions produce electrons on one terminal and store electrons on the other. However, a capacitor is much simpler than a battery, because it can’t produce new electrons— it only stores them. Inside the capacitor, the terminals connect to two metal plates separated by a non-conducting substance known as a dielectric. A capacitor’s storage potential, or capacitance, is measured in farads. A one-farad (1F) capacitor can store one coulomb (1C) of charge at one volt (1V). A coulomb is 6.25x1010 electrons. One amp represents a rate of electron flow of 1C of electrons per second, so a 1F capacitor can hold one ampsecond (1A/s) of electrons at 1V.

Measuring Capacitance The coulombs function of an electrometer can be used with a step voltage source to measure capacitance levels ranging from <10pF to hundreds of nanofarads. The unknown capacitance is connected in series with the electrometer input and the step voltage source.

The calculation of the capacitance is based on this equation:

Figure 1 illustrates a basic configuration for measuring capacitance with an electrometer with an internal voltage source. The instrument is used in the charge (in coulombs) mode and its voltage source provides the step voltage. Just before the voltage source is turned on, the meter’s zero check function should be disabled and the charge reading suppressed by using the REL function to zero the display (The purpose of zero check is to protect the input FET from overload and to zero the instrument. When zero check is enabled, the input of the electrometer is a resistance from roughly 10 megaohms to 100 mega-ohms, depending on the electrometer used. Zero check should be enabled when changing conditions on the input circuit, such as changing functions and connections. The REL function subtracts a reference value from actual readings. When REL is enabled, the instrument uses the present reading as a relative value. Subsequent readings will be the difference between the actual input value and the relative value.)

Figure 1. Capacitance measurement using an electrometer with an integrated voltage source.

6


TECH REPORT Next, the voltage source should be turned on and the charge reading noted immediately. The capacitance can then be calculated from this equation:

where: Q2 = final charge Q1 = initial charge (assumed to be zero) V2 = step voltage V1 = initial voltage (assumed to be zero) After the reading has been recorded, reset the voltage source to 0V to dissipate the charge from the device. Before handling the device, verify the voltage on the capacitance has been discharged to a safe level. The unknown capacitance should be in a shielded test fixture. The shield is connected to the LO input terminal of the electrometer. The HI input terminal should be connected to the highest impedance terminal of the unknown capacitance. If the rate of charge is too great, the resulting measurement will be in error because the input stage becomes temporarily saturated. To limit the rate of charge transfer at the input of the electrometer, add a resistor in series between the voltage source and the capacitance. This is especially true for capacitance values >1nF. A typical series resistor would be 10kΩ to 1MΩ. Refer to Keithley http://www.keithley.com/data?asset=6076 Application Note #315 for details.

Leakage and Insulation Resistance Leakage is one of the less-than-ideal properties of a capacitor, which is expressed in terms of its insulation resistance (IR). For a given dielectric

material, the effective parallel resistance is inversely proportional to the capacitance. This is because the resistance is proportional to the thickness of the dielectric, and inverse to the capacitive area. The capacitance is proportional to the area and inverse to the separation. Therefore, a common unit for quantifying capacitor leakage is the product of its capacitance and its leakage resistance, usually expressed in megohms-microfarads (MΩ·μF). Capacitor leakage is measured by applying a fixed voltage to the capacitor and testing and measuring the resulting current. The leakage current will decay exponentially with time, so it’s usually necessary to apply the voltage for a known period (the soak time) before measuring the current. In theory, a capacitor’s dielectric could be made of any non-conductive substance. However, practical applications use specific materials that best suit the capacitor’s function. The insulation resistance of polymer dielectrics such as polystyrene, polycarbonate, or Teflon® can range from 104MΩ·μF to 108MΩ·μF, depending on the specific materials used and their purity. For example, a 1000pF Teflon cap with an insulation resistance higher than 1017Ω is specified as >108MΩ·μF. The insulation resistance of ceramics such as X7R or NPO can be anywhere from 103MΩ·μF to 106MΩ·μF. Electrolytic capacitors such as tantalum or aluminum have much lower leakage resistances, typically ranging from 1MΩ·μF to 100MΩ·μF. For example, a 4.7μF aluminum cap specified as 50MΩ·μF is guaranteed to have at least 10.6MΩ insulation resistance.

7


Modern Test & Measure Testing Capacitor Leakage

Figure 2. A simple capacitor leakage test circuit.

Figure 2 illustrates a general circuit for testing capacitor leakage. Here, the voltage is placed across the capacitor (CX) for the soak period, then the ammeter measures the current after this period has elapsed. The resistor (R), which is in series with the capacitor, serves two important functions. First, it limits the current in case the capacitor becomes shorted. Second, the decreasing reactance of the capacitor with increasing frequency will increase the gain of the feedback ammeter. The resistor limits this increase in gain to a finite value. A reasonable value is one that results in an RC product from 0.5 to 2 seconds. The switch (S), while not strictly necessary, is included in the circuit to allow control over the voltage to be applied to the capacitor. The series resistor also adds Johnson noise—the thermal noise created by any resistor—to the measurement. At room temperature, this is roughly 6.5×10 -10 amps, p-p. The current noise in a 1TΩ feedback resistor at a typical 3Hz bandwidth would be ~8×10 -16A. When measuring an insulation resistance of 1016Ω at 10V, the noise current will be 80% of the measured current.

Figure 3. Alternative test circuit that incorporates a small-signal diode.

8

Greater measurement accuracy can be achieved by including a forward-biased diode (D) in the circuit, as shown in Figure 3. The diode acts like a variable resistance, low when the charging current to the capacitor is high, then increasing in value as the current decreases with time. This allows the series resistor used to be much smaller because it is only needed to prevent overload of the voltage source


TECH REPORT

Choosing Test Instrumentation A variety of considerations should go into the selection of the instrumentation used when measuring capacitor leakage: ■ Although it is certainly possible to set up a system with a separate voltage source, an integrated one simplifies the configuration and programming process significantly, so look for an electrometer or picoammeter with a built-in variable voltage source. A continuously variable voltage source allows calculating voltage coefficients easily. For making high resistance measurements on capacitors with high voltage ratings, a 1000V source with built-in current limiting is best. For a given capacitor, a larger applied voltage within the voltage rating of the capacitor will produce a larger leakage current. Measuring a larger current with the same intrinsic noise floor produces a greater signal-to-noise ratio and, therefore, a more accurate reading. ■ Temperature and humidity can have a significant effect on high resistance measurements, so monitoring, regulating, and recording these conditions can be critical to ensuring measurement accuracy. Some newer electrometers, such as Keithley’s Model 6517B Electrometer/ Source (Figure 4), have the ability to

monitor temperature and humidity simultaneously. This provides a record of conditions, and allows for easier determination of temperature coefficients. Automatic time stamping of readings provides a further record for time-resolved measurements. ■ Incorporating switching hardware into the test setup allows automating the testing process. For small batch testing in a lab with a benchtop test setup, consider an electrometer that offers the convenience of a plug-in switching card. For testing larger batches of capacitors, look for an instrument that can integrate easily with a switching system capable of higher channel counts.

Figure 4. Model 6517B Electrometer/Source.

9


Modern Test & Measure

and damage to the diode if the capacitor is short-circuited. The diode used should be a small signal diode, such as a 1N914 or a 1N3595, but it must be housed in a lighttight enclosure to eliminate photoelectric and electrostatic interference. For dual-polarity tests, two diodes should be used back to back in parallel.

Test Configurations

Figure 5. Example capacitor leakage test system configuration.

Producing enough useful data for statistical analysis requires testing a large quantity of capacitors quickly. Obviously, performing these tests manually is impractical, so an automated test system is required. Figure 5 illustrates such a system, which employs an electrometer with built-in voltage source, as well as a switching mainframe that houses a low current scanner card and a Form C switching card. In this test setup, a single instrument provides both the voltage sourcing and low current measurement functions. A computer controls the instruments to perform the tests automatically. One set of switches is used to apply the test voltage to each capacitor in turn; a second set of switches connects each capacitor to the electrometerâ&#x20AC;&#x2122;s picoammeter input after a suitable soak period. After the capacitors have been tested, the voltage source should be set to zero and then some time allowed so the capacitors can discharge before they are removed from the test fixture.

Figure 6. Capacitance and IR measurement system.

10

Note that in Figure 5 the capacitors have a discharge path through the normally closed contacts of the relays. To prevent electric shock, test connections must


TECH REPORT be configured in such a way that the user cannot come in contact with the conductors, connections, or the DUT. Safe installation requires proper shielding, barriers, and grounding to prevent contact with conductors. More complex test systems that combine leakage measurement with capacitance measurements, dielectric absorption and other tests, if desired, are possible. A simplified schematic of such a test system using an LCZ bridge and a picoammeter with a voltage source is shown in Figure 6.

Ensuring Test Safety Many electrical test systems or instruments are capable of measuring or sourcing hazardous voltage and power levels. It is also possible, under single fault conditions (e.g., a programming error or an instrument failure), to output hazardous levels even when the system indicates no hazard is present. These high voltage and power levels make it essential to protect operators from any of these hazards at all times. It is the responsibility of the test system designers, integrators, and installers to make sure operator and maintenance personnel protection is in place and effective. Protection methods include:

■ Double insulate all electrical connections that an operator could touch. Double insulation ensures the operator is still protected, even if one insulation layer fails. ■ Use high-reliability, fail-safe interlock switches to disconnect power sources when a test fixture cover is opened. ■ Where possible, use automated handlers so operators do not require access to the inside of the test fixture. ■ Provide proper training to all users of the system so they understand all potential hazards and know how to protect themselves from injury.

■ Design test fixtures to prevent operator contact with any hazardous circuit. ■ Make sure the device under test is fully enclosed to protect the operator from any flying debris.

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CLICK


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Modern Test & Measure

Efficiency Sta Efficiency External STANDARDS Efficiency Standards for Pow External Supplies for Power External

Power Supplies

V IV

VI

V IV

VI

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TECH REPORT

T andards for he global regulatory environment surrounding the legislation of external power supply efficiency and no-load power draw has rapidly evolved over the past decade since the California Energy Commission (CEC) implemented the first mandatory standard in 2004. With the publication of a new set of requirements by the United States Department of Energy (DOE) set to go into effect February 2016, the landscape is set to change again as regulators try to further reduce the amount of energy consumed by external power adapters.

wer Supplies Mandating higher average efficiencies in external power supplies has undoubtedly had a real impact on global power consumption. However, with the benefit of a reduced draw on the power grid come challenges and uncertainties for the electronics industry as it tries to keep up with this dynamic regulatory environment. Original Equipment Manufacturers (OEMs) who design external power supplies into their products must continue to monitor the latest regulations to ensure that they are in compliance in each region where their product is sold. The goal of this paper is to provide an up-to-date summary of the most current regulations worldwide.

15


xternal Power Modern Test & Measure

A BRIEF HISTORY

V IV

VI

16

In the early 90’s, it was estimated that there were more than one billion external power supplies active in the United States alone. The efficiency of these power supplies, mainly utilizing linear technology, could be as low as 50% and still draw power when the application was turned off or not even connected to the power supply (referred to as “no-load” condition). Experts calculated that without efforts to increase efficiencies and reduce “noload” power consumption, external power supplies would account for around 30% of total energy consumption in less than 20 years. As early as 1992, the US Environmental Protection Agency started a voluntary program to promote energy efficiency and reduce pollution, which eventually became the Energy Star program. However, it was not until 2004 that the first mandatory regulation dictating efficiency and no-load power draw minimums was put in place. Figure 1 demonstrates just how dynamic the regulatory environment has been over the past decade. It also traces the path from the CEC’s 2004 regulation up to the new Level VI standards set to take effect February 2016.


Supplies

TECH REPORT

Efficiency Standards for External Power Supplies

Efficiency Standards for External Power Supplies NONE

Figure 1: The image below traces the path from the CEC’s 2004 regulation up to the new Level VI standards set to take effect February 2016

California Energy Commission (CEC)

Passes legislation to impliment their Tier 1 standards in July ‘06 (equivalent to Level III)

PRE

China Energy Conservation Program

2004

2005

LEVEL III

2006

CEC Tier 1

California implements its Tier 1 standards (equivalent to Level III)

LEVEL IV LEVEL VI LEVEL V

2014

Enacts ErP Directive 2009/125/EC with dates to harmonize with CEC and EISA by April ‘11

Energy Star 2010

2012

These efficiency levels are implemented equivalent to Level IV

European Union

2010

US Department of Energy (DOE)

Publishes more stringent Level VI standard

2008

2009

NRCan

Natural Resources Canada implements Tier 1 standards equivalent to Level IV

Enacts the Energy Independence and Security Act (EISA), harmonized with CEC Tier II release date and requirements

CEC Tier 2 & EISA 2007

2008

European Union

Implements Phase 1 of their ErP directive equivalent to Level IV

Implements their Minimum Efficiency Performance standard, (equivalent to Level III)

US Congress 2007

2008

Approves Directive 2005/32/EC establishing a framework for the settingof eco-design requirements, power supplies not defined

Australia

2006

Energy Star

Allows manufacturers to use the Energy Star label if their power supplies meet Level IV standards

2005

2006

Australia

Updates MEPS to include a voluntary High Efficiency category equivalent to Level IV

Implements a voluntary efficiency program, never fully adopted

European Union

2005

Energy Star

Releases international efficiency marking protocol to harmonize all initiatives around the globe

No mandatory standards were set before 2004

2004

Energy Star

Implements a voluntary efficiency program with levels referred to as Tier 1

Voluntary

Removes the power supply category from its listing as they feel it is part of the end product

EISA, CEC & European Union 2011

CEC implements their Tier 3 Standards and EU implements its Phase 2 standards in harmony with Level V Marking Protocol

Level VI Efficiency Standard 2016

Set to go into effect in the US February 10, 2016

Figure 1: This image traces the path from the CEC’s 2004 regulation up to the new Level VI standards set to take 3 2016. effectpage February

17


Modern Test & Measure External Power Supplies

GULATORY ENVIRONMENT

THE CURRENT

ons enact stricter requirements and move from voluntary to mandatory programs, REGULATORY continually track the most recent developments to ensure compliance and avoid any countries are establishing voluntary programs harmonized to the international ENVIRONMENT tem first established by Energy Star, the following countries and regions now have that all external power supplies shipped across their borders and meetregions the specified As different countries enact

Although the United States Department of Energy has established the more stringent Level VI standard, it is not set to go into effect until 2016. Today, Level V will meet or exceed the requirements of any governing body around the globe. Power supply manufacturers indicate compliance by placing a Roman Numeral V on the power supply label as specified by the International Efficiency Marking Protocol for External Power Supplies Version 3.0, updated in September 2013. This latest version of the Protocol provides additional flexibility on where the marking may be placed.

stricter requirements and move from voluntary to mandatory programs, it has become vital that OEMs continually developments CANADA track the most recent EUROPEAN UNION to ensure compliance and avoid costly delays or fines. While many countries are establishing voluntary programs harmonized to the international efficiency marking protocol system first established by Energy Star, the following countries and regions Efficiency Standards for External Powernow Supplies The European Union is currently have regulations in place mandating the only governing body to enforce that all external power supplies shipped compliance to the Level V standard, across their borders meet the specified though most external power supply efficiency level: manufactures have adjusted their artment of Energy has portfolios totomeet these programs, Level VI standard, itAs is different countries and regions enact stricter requirements andproduct move from voluntary mandatory 16. Today, Level V will requirements. The adjustments it has become vital that OEMs continually track the most recent developments to ensure compliance are andaavoid ts of any governing costly body delays or fines. While many countries are establishing voluntary direct response to the needs of international OEMâ&#x20AC;&#x2122;s to programs harmonized to the manufacturers indicate efficiency marking protocol system first established by Energy Star, the afollowing countries and regions now have have universal power supply platform Numeral V on the power regulations in place mandating that all external power supplies shipped across their borders meet the specified for their products that ship globally. International Efficiency efficiency level: ower Supplies Version 3. This latest version of flexibility on where the

THE CURRENT REGULATORY ENVIRONMENT

UNITED STATES

CANADA

the only governing body to enforce compliance to the Level V standard, though nufactures have adjusted their product portfolios to meet these requirements. sponse to the needs of OEMâ&#x20AC;&#x2122;s to have a universal power supply platform for their

18

Although the United States Department of Energy has established the more stringent Level VI standard, it is not set to go into effect until 2016. Today, Level V will meet or exceed the requirements of any governing body

EUROPEAN UNION


TECH REPORT

The internationally approved test method for determining efficiency has been published by the IEC as AS/NZS 4665 Part 1 and Part 2. The approach taken to establish an efficiency level is to measure the input and output power at 4 defined points: 25%, 50%, 75% and 100% of rated power output. Data for all 4 points are separately reported as well as an arithmetic average active efficiency across all 4 points. LEVEL

NO-LOAD POWER REQUIREMENT

AVERAGE EFFICIENCY REQUIREMENT

I

used if you do not meet any of the criteria

II

no criteria was ever established

no criteria was ever established

III

≤10 Watts: ≤0.5W of No Load Power

≤1Watt: ≥ Power x 0.49

10~250 Watts: ≤0.75W No Load Power

1~49 Watts: ≥[0.09 x Ln(Power)] + 0.49 49~250 Watts: ≥84%

IV

0~250 Watts: ≤0.5W No Load Power

≤1Watt: ≥ Power x 0.50 1~51 Watts: ≥[0.09 x Ln(Power)] + 0.5 51~250 Watts: ≥85%

V

Standard Voltage Ac-Dc Models (>6Vout) 0~49 Watts: ≤0.3W of No Load Power

≤1 Watt: 0.48 x Power +0.140

50~250 Watts: ≤0.5W of No Load Power

1~49 Watts: [0.0626 x Ln(Power)] + 0.622 50~250 Watts: ≥87%

Low Voltage Ac-Dc Models (<6Vout) 0~49 Watts: ≤0.3W of No Load Power

≤1 Watt: 0.497 x Power + 0.067

50~250 Watts: ≤0.5W of No Load Power

1~49 Watts: [0.0750 x Ln(Power)] + 0.561 50~250 Watts: ≥86%

past and current performance thresholds as they werewere established over time. term “power” Figure 2: 2: The Thetable tableabove abovesummarizes summarizes past and current performance thresholds as they established over The time. means the power designated on the label of the power supply. The term “power” means the power designated on the label of the power supply.

CURRENT EXEMPTIONS CURRENTor charges the battery of a product that is fully or PERFORMANCE EXEMPTIONS primarily motor operated. THRESHOLDS Not all external power supplies are treated the same Δ Power the charger of a detachable battery pack

and exemptions exist in both the United States and the

Not all external Figure 2 summarizes past and current Δ Arepower made supplies availableare as atreated service part or spare part European Union. the same andby exemptions exist in both performance thresholds as they were the manufacturer of anthe end-product that was United States and the European Union. established over time. The internationally produced before July 1, 2008 for which the external In the US, Congress has written provisions into section approved test method for determining power supply was the primary load. Power supplies 301 of EISA 2007 that exclude some types of external In the US, Congress has written provisions efficiency has been published by the IEC used for this purpose can be manufactured after power supplies. These are devices that: into section 301 of1,EISA 2007 that as AS/NZS 4665 Part 1 and Part 2. The July 2008. Δ Require taken Federal and Drug Administration excludes some types of external power approach toFood establish an efficiency The European Union has instituted similar exemptions listing approval a medical device in supplies. These are devices that: level is toand measure theas input and output to the United States. External power supplies for mediaccordance with section 513 of the Federal Food, power at 4 defined points: 25%, 50%, cal devices, chargers, and service products are Drug, Cosmetic (21 U.S.C. 360c). • Require Federal Foodbattery and Drug Administration 75% andand 100% of ratedAct power output. listing and approval as a medical device in Data for all 4 points are separately accordance with section 513 of the Federal reported as well as an arithmetic average page 5 Food, Drug, and Cosmetic Act (21 U.S.C. 360c). active efficiency across all 4 points. • Powers the chargers of a detachable battery packs or charges the battery of a product that is fully or primarily motor-operated.

19


Δ Products with power levels >250 watts than or equal to 550 mA.

Modern Test & Measure

The new performance thresholds are summarized in the tables below:

MOVING TO LEVEL VI

• Are made available as a service part or spare part by the manufacturer of an end-product that was produced before July 1, 2008 for which the external power supply was the primary load. Power supplies used for this purpose can be manufactured after July 1, 2008.

1 Power supply manufactures, including CUI, are already SINGLE-VOLTAGE EXTERNAL AC-DC POWER SUPPLY , BASIC-VOLTAGE

preparing for the coming transition Maximum to the more Nameplate Minimum Average Power Output Power Efficiency in Active Mode in No-Load Mode stringent Level VI standards. Along with tightened (Pout ) (expressed as a decimal) (W)

regulations for existing adapters, the new standard 0.5 × P + 0.16 0.100 the products fall under the 49 W 0.071range × ln(P ) -of 0.0014 × P + 0.67that0.100 1 W < Pexpands 0.880 0.210 include: 49 W < standard. P 250 W Regulated products will now Pout 1 W

out

out

out

out

Pout > 250 W

The European Union has instituted similar exemptions to the United States. External power supplies for medical devices, battery chargers, and service products are exempt. In addition, an exemption exists for low volt- age EPS devices. Low voltage external power supply means a unit with a nameplate output voltage of less than 6 volts and a nameplate output current greater than or equal to 550 mA.

regulations for existing adapters, the new standard expands the range of products that fall under the standard. Regulated products will now include:

TO LEVEL VI

• Multiple-voltage external anufactures, including CUI, are already power supplies e coming transition to the more I standards. Along with tightened • Products with power levels xisting adapters, the new standard greater than 250 watts ge of products that fall under the The new will performance thresholds are ated products now include:

summarized in the tables at the right:

ge external power supplies

power levels >250 watts

mance thresholds are summarized in :

20

0.875

0.500

Δ Multiple-voltage external power supplies

Δ Products with power levelsSUPPLY, >250LOW-VOLTAGE watts 2 SINGLE-VOLTAGE EXTERNAL AC-DC POWER Nameplate Minimum Average The new performance thresholds Output Power Efficiency in Active Mode (Pthe ) (expressed as a decimal) out tables below: Pout 1 W

1W<P andards for External Power Supplies

ion, anMOVING exemption TO exists for lowVI voltLEVEL . Low voltage external power supply Power supply manufactures, including h a nameplate output voltage of less CUI, are already preparing for the a nameplate output current greater coming transition to the more stringent Level VI standards. Along with tightened 550 mA.

out

49 W

out

Maximum Power are summarized in in No-Load Mode (W)

0.517 × Pout + 0.087

0.100

0.0834 × ln(Pout) - 0.0014 × Pout + 0.609

0.100

49 W < Pout 250 W

0.870 0.210 1 , BASIC-VOLTAGE SINGLE-VOLTAGE EXTERNAL AC-DC POWER SUPPLY

Pout > 250 W

0.875

0.500

Nameplate Minimum Average Maximum Power Output Power Efficiency in Active Mode in No-Load Mode (Pout ) (expressed as a decimal) (W) 3 SINGLE-VOLTAGE EXTERNAL POWER SUPPLY , BASIC-VOLTAGE Pout 1 W 0.5 ×AC-AC Pout + 0.16 0.100

0.071 × ln(PAverage 0.100 1 W < Pout 49 W out) - 0.0014 × Pout + 0.67 Nameplate Minimum Maximum Power Output49Power in No-Load 0.880 in Active Mode 0.210Mode W < Pout 250 WEfficiency (Pout ) (expressed as a decimal) (W)

Pout 1 W

Pout > 250 W

1 W < Pout 49 W

page 6 49 W < P

out

Pout > 250 W

250 W

0.875 0.5 × Pout + 0.16

0.210

0.071 × ln(Pout) - 0.0014 × Pout + 0.67

0.210

0.880

0.210

0.875

0.500

0.500

SINGLE-VOLTAGE EXTERNAL AC-DC POWER SUPPLY, LOW-VOLTAGE 2

Nameplate Minimum Average Maximum Power Output Power Efficiency in Active Mode in No-Load Mode (Pout ) (expressed as a decimal) (W) SINGLE-VOLTAGE EXTERNAL AC-AC POWER SUPPLY, LOW-VOLTAGE Pout 1 W 0.517 × Pout + 0.087 0.100 0.0834 × ln(PAverage 0.100 1 W < Pout 49 W out) - 0.0014 × Pout + 0.609 Nameplate Minimum Maximum Power Output49Power Efficiency in Active Mode in No-Load 0.210Mode W < Pout 250 W 0.870 (Pout ) (expressed as a decimal) (W) 0.875 0.500 P > 250 W

Pout 1 W

out

0.517 × Pout + 0.087

0.210

1 W < Pout 49 W

0.0834 × ln(Pout) - 0.0014 × Pout + 0.609

0.210

49 W < Pout 250 W

0.870

0.210

Pout > 250 W

0.875

0.500

MULTIPLE-VOLTAGE EXTERNAL POWER SUPPLY4 Nameplate page 6 Output Power (Pout )

Minimum Average Efficiency in Active Mode (expressed as a decimal)

Maximum Power in No-Load Mode (W)


Pout 1 MULTIPLE-VOLTAGE W 0.5 × PoutEXTERNAL + 0.16 POWER SUPPLY4

0.210

1 W < Pout 49 W

0.210

0.071 × ln(Pout) - 0.0014 × Pout + 0.67

Nameplate Minimum Average 0.880 in Active Mode W < Pout 250 WEfficiency Output49Power (Pout (expressed as a decimal) 0.875 Pout )> 250 W Pout 1 W

0.497 × Pout + 0.067

0.300

1 W < Pout 49 W

0.075 × ln(Pout) + 0.561

0.300

Pout > 49 W

1

Maximum Power 0.210Mode in No-Load (W) 0.500

TECH REPORT

0.860 0.300 SINGLE-VOLTAGE EXTERNAL AC-AC POWER SUPPLY, LOW-VOLTAGE

Nameplate Minimum Average Maximum Power Single-Voltage External Ac-Dc Power Supply Output Power Efficiency in Active Mode in No-Load Mode decimal) (W) An external(P power is designedas to aconvert line voltage ac into out ) supply that(expressed lower-voltage dc output and is able to convert to only one dc output Pout 1 W 0.517 × Pout + 0.087 0.210 voltage at a time. 1 W < Pout 49 W 49 W < P

250 W

0.0834 × ln(Pout) - 0.0014 × Pout + 0.609

0.210

0.870

0.210

2

Low-Voltage out External Power Supply W supply 0.875 Pout > 250 An external power with a nameplate output voltage less0.500 than 6 volts and nameplate output current greater than or equal to 550 milliamps. Basic-voltage external power supply means an external power supply that is not a low-voltage power supply. MULTIPLE-VOLTAGE EXTERNAL POWER SUPPLY4

3

Single-Voltage External Ac-Ac Power Supply Nameplate Minimum Average Maximum Power An external power supply that Efficiency is designed convert line voltage ac into Mode Output Power in to Active Mode in No-Load (Pout as a decimal) lower-voltage ac )output and is(expressed able to convert to only one ac output (W) voltagePoutat 1a W time. 0.497 × Pout + 0.067 0.300

4

Multiple-Voltage External Power Supply 0.860 0.300 Pout > 49 W An external power supply that is designed to convert line voltage ac input into more than one simultaneous lower-voltage output.

1 W < Pout 49 W

0.075 × ln(Pout) + 0.561

0.300

1. 1 Single-Voltage External AC-DC Power Supply Single-Voltage External Ac-Dc Power Supply An external power supply that is designed to convert line voltage AC into An external power supply that is designed to convert line voltage ac into lower-voltage DC output and is able to convert to only one DC output lower-voltage dc output and is able to convert to only one dc output voltage at a time

voltage at a time.

2. Low-Voltage External Power Supply 2 An external power supply with a nameplate output voltage less than Low-Voltage External Power Supply 6 volts and nameplate output current greater than or equal to 550 An external power supply with a nameplate output voltage less than milliamps. Basic-voltage external power supply means an external 6 volts and nameplate output current greater than or equal to 550 power supply that is not a low-voltage power supply.

milliamps. Basic-voltage external power supply means an external power

3. Single-Voltage External AC-AC power Powersupply. Supply supply that is not a low-voltage An external power supply that is designed to convert line voltage AC into 3 lower-voltage AC output and is able to convert to only one AC output Single-Voltage External Ac-Ac Power Supply voltage at a time.

An external power supply that is designed to convert line voltage ac into

4. Multiple-Voltage E xternal lower-voltage ac output andPower is ableSupply to convert to only one ac output An external voltage at a power time. supply that is designed to convert line voltage AC input into more than one simultaneous lower-voltage output. 4

Multiple-Voltage External Power Supply An external power supply that is designed to convert line voltage ac input into more than one simultaneous lower-voltage output.

21


Efficiency Standards for External Power Supplies

Modern Test & Measure

DIRECT VS INDIRECT DIRECT VS. INDIRECT OPERATION EPSs

OPERATION EPSS The new standard also defines power supplies as direct The newoperation standardand alsoindirect definesoperation power products. A direct operation product is and an external supplies as direct operation indirect power supply (EPS) that functions in its end product without the operation products. A direct operation product is anof external power supply operation EPS assistance a battery. An indirect (EPS) functions in itsbut endcannot product is notthat a battery charger operate the end without the assistance of a battery. An product without the assistance of a battery. The new indirect operation EPS is a battery standard only applies tonot direct operation external charger but cannot operate the end models will still be power supplies. Indirect operation product without assistance of aby EISA2007. Figure governed by thethe limits as defined battery. The new standard only applies 3 illustrates the instructions provided by the DOE to tohelp direct operationbetween externaldirect power distinguish and indirect operation supplies. Indirect operation models power supplies: will still be governed by the limits as defined by EISA2007. Figure 3 illustrates the instructions provided by the DOE to help distinguish between direct and indirect operation power supplies: The new Level VI mandate also defines exemptions

1

step i If the end-use product has a removable battery, remove it for the remainder of the test and proceed to step (v). If not, proceed to step (ii).

step ii Charge the battery in the application via the EPS such that the application can operate as intended before taking any additional steps.

step iii

LEVEL VI EXEMPTIONS

Disconnect the EPS from the application. From an off mode state, turn on the application and record the time necessary for it to become operational to the nearest five second increment (5 sec, 10 sec, etc.).

for EPS products. The direct operation EPS standards do not apply LEVEL VI if:EXEMPTIONS

step iv

The mandate also defines Δ Itnew is aLevel deviceVIthat requires Federal Food and Drug exemptions for EPSlisting products. The direct Administration and approval as a medical operation standards with do not apply 360c if: device EPS in accordance section of title 21;

Operate the application using power only from the battery until the application stops functioning due to the battery discharging.

step v

OR

• It is a device that requires Federal Food and Drug Administration listing Δ A direct operation, ac-dc external power supply with and approval as a medical device in nameplate output voltage less than 3 volts and accordance with section 306c of title 21;

Connect the EPS first to mains and then to the application. Immediately attempt to operate the application. If the battery was removed for testing and the end-use product operates as intended, the EPS is not an indirect operation EPS and paragraph 2 of this definition does not apply.

nameplate output current greater than or equal to 1,000 milliamps that charges the battery of a product that is fully or primarily motor operated.

If the battery could not be removed for testing, record the time for the application to become operational to the nearest five second increment (5 seconds, 10 seconds, etc.).

OR

• A direct operation, AC/DC external power supply with nameplate output voltage less than 3 volts and nameplate output current greater than or equal to 1,000 milliamps that charges the battery of a product that is fully or primarily motor operated.

page 7

22

If the external power supply (EPS) can be connected to an end-use consumer product and that consumer product can be operated using battery power, the method for determining whether that EPS is incapable of operating that consumer product directly is as follows:

2

If the time recorded in paragraph (1)(v) is greater than the summation of the time recorded in paragraph (1)(iii) of this definition and five seconds, the EPS cannot operate the application directly and is an indirect operation EPS.

Figure 3. The above instructions have been provided by the DOE toabove help distinguish direct and indirect Figure 3: The instructionsbetween have been provided by the operation power supplies. DOE to help distinguish between direct and indirect operation power supplies.


TECH REPORT LOOKING FORWARD

SUMMARY

The compliance date for the new requirements has been set for February 10, 2016, two years after the rule’s publication in the Federal Register. It is important to note that compliance with the new standard will be regulated from the date of manufacture, so legacy products can still be shipped as long as the manufacture date is prior to February 10, 2016. Labeling requirements will be required to meet the same International Efficiency Marking Protocol for External Power Supplies Version 3.0 as the current Level V standard.

The EPA estimates that external power supply efficiency regulations implemented over the past decade have reduced energy consumption by 32 billion kilowatts, saving $2.5 billion annually and reducing CO2 emissions by more than 24 million tons per year. Moving beyond the mandated government regulations, many OEMs are now starting to demand “greener” power supplies as a way to differentiate their end-products, driving efficiencies continually higher and even pushing the implementation of control technologies that in some cases eliminates no-load power consumption altogether. In late 2014, CUI Inc. began introducing Level VI compliant adapters to keep their customers one step ahead of the coming legislation. Moving forward, CUI will continue to look for ways to implement the latest energy-saving technologies into their external power supplies in order to address market demands and comply with current and future regulations. View all Level V and Level VI compliant power http://www.cui.com/catalog/powsupplies at www.cui.com/catalog/power/ er/ac-dc-power-supplies/external ac-dc-power-supplies/external.

Globally, it is expected that other nations will soon follow suit with this standard. In the EU, the mandatory European Ecodesign Directive for external power supplies is currently going through revision discussions and it is expected to harmonize with most, if not all, of the US standards. It should be expected that countries with existing efficiency regulations in-line with the US, including Canada and Australia, will move to harmonize with the new standard as well.

23


Modern Test & Measure

From

NEWCOMER

to GLOBAL

LEADER Interview with Steve Barfield General Manager of Siglent

24


INDUSTRY INTERVIEW

Siglent’s Rise to the Top of the Chinese Scope Market

S

teve Barfield has been in the Test & Measure industry since the 1970s. Back then, the big player in the field was Hewlett Packard—one of the only

companies offering advanced test equipment. In the following years, the industry has taken off, with hundreds of big name companies dominating the markets— each offering their own spin on these classic devices. While customers tend to go with the brands they trust, Barfield feels there should be more emphasis on overall engineering experience: better specs, better support, and lower price. This is why Barfield joined Siglent, a relatively new test equipment company that is making its mark in the field. EEWeb spoke with Barfield about some of the ways Siglent differentiate themselves from more familiar brands and how this approach has led to explosive growth in the Chinese market.

25


Modern Test & Measure

You’ve been in the Test & Measure field for quite some time. What has led you to your current position at Siglent?

What are some of the challenges and opportunities in trying to establish a brand in the test and measurement industry?

I started my career at Hewlett Packard in Dallas back in the late 1970s. I really came to love test and measurement instrumentation—I even started to build my own as a hobby. As long ago as this was, I can still see a piece of old HP equipment from across the room and tell you exactly what model it is and the basic specs.

Back in the day, there were only a handful of test and measurement companies in the industry. Customers either bought from HP, from a select few competitors, or they made their own equipment. Today, there are many more players in the field, and the technology is certainly a lot different than it was in those days. Many would consider Siglent to be the “new kid on the block” in terms of brand recognition. While we were founded in 2002, Siglent is the leading oscilloscope manufacturer in China as far as number of shipments. We do ODM products for several well-known companies here in the US as well as overseas.

Since then, I worked as a distributor of test and measurement equipment and then on to sales and sales management. In 2011, I moved to Cleveland, where I was a sales manager for Rigol and when they moved to Oregon, I stayed here to help open the new Siglent offices in Cleveland. By being in the sales department with test and measurement equipment manufacturers, you get to see a lot of different industries and companies. I have been in factories where they did the final assembly of nuclear warheads, and others that were developing new automobiles that needed to have testing done—if you like seeing many different technologies and products, then it is a fun place to be.

The challenge for us is to make a product that meets the needs of the customer at a lower price.

26

As far as challenges go, when you are new and are competing against veteran companies with recognizable names, it is hard to win customer trust overnight. There are no shortcuts to winning customer trust—it does take time. I do believe that whenever someone uses a Siglent product and gets their hands on it, they begin to gain confidence in it; that is one of the ways we will continue to grow. More and more customers will take the first step and try out a piece of Siglent equipment. We also plan on continuing to be a major ODM supplier. Our job is to make customers aware of us, build trust in our brand, and get them to try Siglent products.


INDUSTRY INTERVIEW What are some of the opportunities that you see as a smaller company? A multi-million dollar company that has been around for a number of years has its advantages. However, being a newer company, Siglent has its own unique advantages. One that comes to mind is that we can move quicklyâ&#x20AC;&#x201D;in some ways, quicker than any larger company. For example, when we recommend a change, option, or new product, those things can happen faster than at a larger company. In August, I was told of a new spectrum analyzer that Siglent is developing. I recommended certain features that I thought would be important and, to my surprise, at Electronica last November, we had a prototype of that very spectrum analyzer with those features I suggested. Another big advantage of a small company is that communication is easier. Since I have been with Siglent I have communicated on an almost daily basis with Eric Qin, the CEO of Siglent. People here at the office can make contact with just about anyone at our headquarters so they are empowered to get things done on their own. There are fewer channels and chains of command to deal with.

You mentioned being able to move quickly with product development, which is a key factor in a lot of niche markets. What are some of the niche markets that Siglent plans to serve? Right now, we are still targeting broader markets. When a new customer asks what we do, I usually mention that if their product has a battery or power cord, it could probably use the type of measurement instruments that we make in their design, test, and manufacturing phases of product development. In that sense, we have an extremely broad customer base. We also have our ODM business, which is really important to us. We came in to the US market by selling to small companies and individuals, which is changing as we are getting larger and developing more sophisticated instrumentation. We have a new spectrum analyzer coming out that will have a feature set that will make it ideal for lowcost EMC pre-compliance testing. Virtually every company that makes an electronic product has to go through EMC compliance testing, and performing the pre-compliance testing in-house saves them a great deal of time and money (compared to outsourcing it). There is virtually no downside to buying your own appropriate lowcost spectrum analyzer compared to sending it out for pre-compliance testing at a certified testing lab.

27


Modern Test & Measure

What are the key differentiations in Siglent’s products?

In order to be a new company in this crowded market, you need to do something different to survive. This means more features, better specs, lower price, or better support.

Siglent’s Brand-new SDM3055 Digital Multimeter

28

Siglent Technologies manufactures oscilloscopes, power supplies, DMMs, ARB/function generators, and coming soon, spectrum analyzers. In order to be a new company in this crowded market, you need to do something different to survive. This means more features, better specs, lower price, or better support. Siglent strives to do all of that. We have to distinguish ourselves against these much larger brands, so we have been focusing on overall better value for our customers, and a lot of that comes from better support. People like to buy from companies that they know and trust, so one of our goals here is to do any type of repair in ten days or less. If you want to be the best, you have to be willing to work harder and provide more for the customer at a lower price. Siglent is able to do this. As far as our products go, Siglent does not make 20GHz oscilloscopes or 10kW power supplies—what we do make are the most commonly used test and measurement products. Our scopes have very large memories, fast hardware, and options that can be added in the field if necessary. Our generators have what we call “EasyPulse” technology, which gives the user faster transition times and more adjustment ranges compared to similar units from other companies.


INDUSTRY INTERVIEW The challenge for us is to make a product that meets the needs of the customer at a lower price. Almost everyone is facing tighter budgets than they used to, so if they can equip their lab with two to three workstations at the same price that they used to spend on one station, as well as having more capabilities and better features, then we have succeeded.

Given your previous role at Rigol, what did you learn there that has helped guide you at your current role at Siglent? In a lot of ways, Siglent is in the same place that Rigol was in the United States a few years ago. This is not surprising because we came to the US several years after they did. For me, I think the experience of helping grow a relatively new Chinese-based test and measurement company in North America—which is what I did at Rigol—is helping me now at Siglent. I am a big believer that every job we hold throughout our careers can help us in doing a better job in our later positions. If we are willing, we can learn important lessons and gain valuable experience from every position we have.

What is your favorite piece of test equipment? I would say the oscilloscope is my favorite. An oscilloscope is the most used piece of equipment on many engineers’ benches. When I worked for HP back in the day, I worked with customers to show them the differences between our models and the competitions’. Through this, I became the top scope salesman in the South during my first year at HP. If you approach a new customer and ask them to look at your model of scope, they can become disillusioned with it if they have to re-learn the functions and how to use it. A customer has to sit down and use the scope for a while in order to feel comfortable with it. I understood why scopes were so important to customers, which is why I was able to convince customers to be receptive to changes in equipment.

Whenever someone uses a Siglent product and gets their hands on it, they begin to gain confidence in it; that is one of the ways we will continue to grow.

29


Modern Test & Measure

Siglentâ&#x20AC;&#x2122;s

EasyPulse Technology

for New-Generation Waveform Generators

A

t present, the method used to generate pulse signals by most ARB/function generators is to fill the DDS waveform memory with the original pulse data. By editing the pulse waveform data table in advance, DDS can output the right pulse waveform corresponding with the separate rising and falling edges. The edge and width of this pulse waveform can be finely adjusted, and also contains low jitter. This traditional method is represented in the following block diagram (figure 1.)

Phase Tuning Word

Figure 1.

30


TECH REPORT

However, this method comes with some disadvantages: • Waveforms are affected by the signal’s frequency, meaning the rising and falling edge transition time will be limited at low frequencies. • The output pulse will be limited by waveform length, so the duty cycle cannot be very small. • Waveform data will need to be updated when changing the pulse’s frequency, edge, and width. If the waveform length is large, it needs more time to change the other parameters of the pulse. To solve these problems, Siglent innovated a new algorithm for pulse generation, called EasyPulse technology, which is built in the new SDG5000 and SDG800 series waveform generators.

Based on the EasyPulse architecture, the SDG5000 and SDG800 can produce low-jitter, rapid rising, and falling edge, without being affected by frequency or extreme duty cycle. The pulse transition time can be adjusted over a larger range, and fine resolution. The EasyPulse method is illustrated in the following block diagram: Siglent’s EasyPulse technology comes with significant advantages. For one, it can output rapid rising and falling edges (6ns), even at very low frequencies (less than 1Hz); and the pulse width can be 12ns under low frequency, with very long or short duty cycles. Parameter changes such as pulse can be easily and immediately changed without updating any waveform data and the edge and pulse width can be adjusted over wide ranges.

Phase Tuning Word

Figure 2.

31


Modern Test & Measure

The EasyPulse Advantage in Four Measurements

1

As indicated here, EasyPulse can keep rapid rising and falling edges (6ns); but the ordinary DDS pulse edge is very slow (in millisecond).

Comparison of Pulse signal edge under 1Hz low frequency

Comparison of pulse duty cycle under 1Hz low frequency

32

2

For 1Hz pulse waveforms, the minimum width of EasyPulse can be 12ns with small duty ratio (less than 0.0001%). But pulse width of ordinary DDS is large and duty cycle cannot be adjusted to small values.


TECH REPORT

3

When waveform generator outputs 0.1Hz pulse waveform, the edge of EasyPulse can be adjusted over a large range, with a minimum edge of 6ns, and maximum edge of 6s. However, there is a limitation on the adjustment of the ordinary DDS pulse edge.

Comparison of edge adjustment of low frequency 0.1Hz pulse signal

4

Using Siglent oscilloscopes to measure the cycle-tocycle jitter of EasyPulse, the RMS value (sdev value) is under 100ps.

EasyPulse waveform with low jitter

33


Modern Test & Measure

When stating the low jitter performance of EasyPulse, the disadvantages of DDS on jitter become more apparent. When DDS generates a pulse, if the reference frequency is not exactly the integral multiple of output frequency (i.e. mod(fref/fout )â&#x2030; 0), it will introduce a deterministic jitter equal to one reference clock period, as shown in the figures at right.

Period

Maximum 1000000s: Minimum 25 ns

Pulse Width

â&#x2030;Ľ 12ns, 100ps resolution

Duty Cycle

0.0001% ~ 99.9999%

Rise/Fall time

6ns ~ 6s, 100ps resolution

Over Shoot

< 3%

Jitter (Cycle to Cycle )

<=200ps + 2ppm, DC-1MHz; <= 500ps, over 1 MHz

Table 1. Technical specifications for a pulse signal of the SDG5162 waveform generator.

(In the figure the reference clock period is 20ns)

34


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Modern Test and Measure: February 2015  

From Newcomer to Global Leader: Siglent's Rise to the Top in the Global Scope Market

Modern Test and Measure: February 2015  

From Newcomer to Global Leader: Siglent's Rise to the Top in the Global Scope Market

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