LM-80 Thermal Control Vektrex LM-80 thermal control systems (ITCS chambers) utilize water-based, closed-loop active control to provide efficient and uniform thermal control for semiconductor devices. Temperature Uniformity within 2°C LM-80 thermal control systems with tightly-regulated temperature uniformity are essential to the successful LM-80 testing of LEDs, modules, arrays, COB, high power devices, mid power devices, and low power devices. With up to 10kW of power handling capability – at operating temperatures up to 150C – the ITCS chamber provides the flexibility to test numerous high power device types in a single chamber and maintain temperature uniformity within 2C. Features: Up to 10kW heat dissipation, temperatures to 150C Energy-efficient thermal control using plant water Tcase, Tambient, and Tsink monitoring and data logging Isolated thermocouples Capacity – 40 load boards; up to 1,600 devices Five slide-out drawers, easy load and unload NVLAP auditable and traceable Calibration and validation certificates Worldwide install base Contaminant-free construction No VOC producing components used Factory acceptance testing to ensure ITCS does not contaminate devices Comprehensive Test Software Vektrex software applications are designed to address and support a wide range of testing needs. The LM-80 software suite includes STARS testing and monitoring software that controls and monitor source channels, loads, and thermal control devices during testing. From plotting data and identifying trends to failsafe protection and remote thermal control, Vektrex software simplifies test control and accurate data collection. STARPLOT software allows operators to verify ITCS temperature uniformity, ultimately leading to more repeatable, reliable test results. read more

LM-80 Drive Electronics Drive/power electronics for LM-80 testing form the foundation for successful testing.  Selecting the best drive electronics is a very important decision.     Drive Electronics Cabinet Selection criteria for your LM-80 drive/power electronics should include the following: LM-80-08 Testing Requirements Constant Current (DC mode)   (yes, with SpikeSafe current source; user selectable currents) Pulse mode current (allowed LM-08-15)  (yes with SpikeSafe current source; user selectable currents and pulse settings) Current accuracy less than 3%  (yes. SpikeSafe current source accuracy is less than 1%) Temperature measurement monitoring and data logging (thermocouple – special limits wire) (yes) Alternate temperature measurement monitoring techniques – RTD or thermistor (yes) Minimum 6,000 hours test time (10,000 recommended)  (SpikeSafe MTBF 10,000 hours) Duration timers set by operators stop testing and alert users that it is time for light measurements Test Timing Uncertainty for the software application must be calculated to ensure minimum testing is achieved (yes) RH less than 65% AC ripple less than 2% (yes, with SpikeSafe current source) NVLAP Self Certification LM-80 audit (Vektrex systems have been successfully audited and are in use in many countries) Other criteria for selection of your LM-80 drive / power electronics Is the system constructed from high quality components? What is the uptime and MTBF? What is the Energy Efficiency? Does the system include safety mechanisms for operators and devices? What is the worldwide installation base? Does the system meet the LM-80 Specifications? Is the system NVLAP auditable? Does the software support the test requirements? Does the software include management functions that simplify test management? Are you able to easily detect test anomalies? Is the system scaleable and modular? Does the system support a large voltage and current range ? Vektrex LM-80 drive electronics are based upon industry standard SpikeSafe modules. read more

LM-80 Test Solutions Vektrex offers complete LM-80 test solutions that meet all IESNA and Energy Star testing criteria. Vektrex actively participates on the LM-80 committee, chairing the LM-80 working group moving this standard through the acceptance process and into IEEE acceptance. High-capacity Vektrex LM-80 Systems combine spike-protected, constant or pulsed current LED drive electronics with fully integrated thermal control systems and automated light measurement. Vektrex LM-80 Systems are optimized for LM-80-08 and LM-80-15 compliance testing for low, mid and high power LEDs, modules, COBs, and arrays operating in infrared, visible, or UV. Vektrex LM-80 Systems are also applicable for use with laser diodes. Full Vektrex IESNA LM-80 System. Industry-Leading Drive Electronics Energy-efficient Vektrex SpikeSafe™ Series current sources supply DC and precision-pulsed drive current up to 50A at voltages up to 400V for LM-80 testing and high-power LED reliability stress applications. Multiple-source channel modules deliver high capacity and high power density with the testing flexibility of independent channel control. SpikeSafe™ load protection continuously monitors voltage and current on all source channels and instantly shuts down when device anomalies are detected. Rapid shutdown preserves the failure device for analysis, protects other devices, reduces failure counts, and improves reliability results. High-Capacity Thermal Control Temperature uniformity is essential to successful LM-80 testing. Vektrex Integrated Thermal Control Systems (ITCS) use plant chill water and a closed loop system for uniform thermal control in a compact, energy-efficient footprint. With up to 10kW of power handling capability – at operating temperatures up to 150C – the Vektrex ITCS provides the capacity to test numerous high power devices in a single chamber. Integrated fixturing with convenient slide-out drawers simplify loading and unloading. Available individual drawer temperature controls allow side-by-side testing of multiple device types with different thermal characteristics. Repeatable Light Measurement The Vektrex Automated Light Measurement System integrates thermal control and precise electrical and optical instrumentation with easy-to-use software tools for measuring and recording LM-80 photometric and electrical test results. Single pulse, DC and continuous pulse modes are compliant with LM-85 requirements for repeatable high power LED light measurement. With 0.05% flux repeatability, the Vektrex Automated Light Measurement System can detect LED test trends within hours. Comprehensive Test Software Vektrex software applications are designed to address and support a wide range of testing needs. The LM-80 software suite includes STARS testing and monitoring software that controls and monitor source channels, loads, and thermal control devices during testing. STARPLOT software application graphically presents a view of reliability data generated by STARS. STARPLOT provides a graphical view of reliability data where defects such as internal shorts in LED arrays, connector wear, and even thermal problems may be identified. From plotting data and identifying trends to failsafe protection and remote thermal control, Vektrex software simplifies test control and accurate data collection. Confidence Whether you’re expanding existing test capacity, or stepping up to higher-power LM-80 LED testing systems, Vektrex systems and components give you the flexibility to scale a wide range of LED testing configurations. Leading manufacturers and LM-80 labs worldwide rely on Vektrex systems and components for unmatched power, capacity, and reliable performance. Key LM-80 Requirements Vektrex Exceeds the Requirements Constant Current Drive (DC Mode) PWM Drive / Pulsed Current Accuracy < 3% SpikeSafe™ Protected Modular Current Sources, available to 400V, 50A DC and Precision Pulsing Individual Source Channel Control Typical Current Accuracy 0.1% MTBF 175,000 Hours Accurate Time Keeping Typically 6,000 – 10,000 Hours Duration DUT Failure Recording Logs Data, Monitors Errors & Faults, Duration Timers, Data Visualization Two or More Test Temperatures -2 to ∞ Case Temperature Control -5 to ∞ Air Temperature Control to 150C Operation, 0.2C Stability, up to 10kW / Chamber Load UV, IR, VIS, & Array Device Support Spectrometer-based Measurements Selectable Measurement Temperature Automatically Tests up to 80 DUTs Repeatable to 0.05% Flux Measurement LM-85 Capable Test Timing Uncertainty Analysis Numerous NVLAP Certified Installations LM-80 Training LM-80-XX (2018) Working group tasked to add laser diodes and filament LED lamps to the LM-80 standard. Jeff Hulett, Vektrex, chairs their working group. LM-80-15 (2015) Scope expanded to include radiant, photon or luminous flux maintenance Air temperature control required (shall) Alternate temperature sensor acceptable  (RTD, Thermocouple, Thermistor) Case temperature taken at manufacturers designated measurement point Any light measurement temperature may be used Specific methods for monitoring case temperature All DUTs shall be tracked No seasoning or aging prior to test Drive types expanded to include PWM, AC Regulated Voltage, Constant Voltage Eliminate ripple and total harmonic distortion requirements LM-80-08 Addendum (2012) Test temperatures reduced to two, one of which must be 55C or 85C Different currents may be used at the different test temperatures Interpolation per TM-21 to predict luminous flux maintenance requires the same drive current for the two temperatures Testing at three or more temperatures offers more accurate interpolations Key LM-80-08 (2008)/Energy Star Testing Requirements; Minimum 20 device test lot per device family Minimum 10 device test lot for modules Constant Current (DC mode) only Current accuracy better than 3% Three Test Temperatures: 55C, 85C, and one other selected by the manufacturer Thermocouples MUST be used for temperature measurement (special limits wire) Case temperature shall be maintained at a temperature greater than or equal to 2C below the test temperature Air temperature should be maintained at a temperature greater than or equal to 5C below the test temperature Minimum 6,000 hours test time (10,000 recommended) Light Measurements collected at T0 and generally every 1,000 hours. Light Measurements taken at 25C. Test Timing Uncertainty for the software application must be calculated to ensure minimum testing is achieved RH less than 65% Record Lumen Maintenance, Chromaticity, and Catastrophic failures 17025 Lab Certification NVLAP Self Certification and LM-80 audit The LM-80 standard is accepted worldwide. The intent is for LEDs and LED devices to be tested in several standardized operating conditions.  The data resulting from LM-80 measurements are matrices of lumen maintenance values. LM-80 defines a standardized report output for the data. LED manufacturers use this data to predict the LED light output over the life, improve their processes, and compare their devices with other competitor devices.  Users of LEDs (for example Lighting Designers) use this standardized data to select the appropriate LEDs for their application and, in conjunction with TM21, to correctly define the warranty period.  In the USA, LM-80 testing is required for Energy Star Certification. read more

Thermal Measurements Thermal measurements are used in a variety of applications involving LEDs, laser diodes and VCSELs. The measurements utilize the Electrical Test Method (ETM), and they fall in to two broad categories: measurements of the device’s junction temperature, and determination of thermal resistance including measurements of the thermal path from the junction to an exterior point. These thermal measurements are used by solid-state device scientists to understand and improve devices, by test engineers when making optical measurements, and by luminaire / fixture designers to understand the thermal performance of lighting products. SpikeSafe Pulsed SMU The SpikeSafe SMU supports all these measurements, from simple Tj assessment to complex thermal analysis using structure functions. The SMU powers the LED or laser during thermal measurements using its primary and bias current sources, and its digitizer records the forward-voltage (VF) readings needed to calculate temperature. This voltage data is then processed by external software to complete the desired measurement. The supported LED and laser thermal measurements include: In-situ Tj for individual LEDs or luminaires Tj change during photometric measurements Tj rise during pulsed operation Thermal resistance Heat path analysis using structure functions Each measurement is explained in more detail below. Vektrex-supplied components for the specific application are described. Custom software (see Python examples) may also be used to make automated thermal measurements using the SpikeSafe SMU. In-situ Tj Measurement for Individual LEDs or Luminaires The Junction Temperature (Tj) is the operating temperature of the LED or laser diode’s semiconductor junction. When operating, the Tj of a semiconductor is higher than the surrounding ambient environment, and the heat dissipated in the semiconductor flows through a path that includes the various packaging components such as solder, MCPCB, and heat sink. This is illustrated in the diagram below. Typical LED Heat Flow Path Tj has a direct impact on the long-term reliability of a laser or LED. Higher in-situ Tj leads to reduced long-term reliability. At temperatures above 150 ˚C the device may fail immediately. Tj also impacts the operating characteristics of LEDs and lasers. For example, an amber LED’s light output decreases dramatically as junction temperature increases. LED manufacturers typically provide performance specifications at a specific Tj along with derating factors that allow performance at other temperatures to be calculated. Using these values, along with actual in-situ measurements, product designers verify the product will perform within its advertised specifications. The in-situ junction temperature is the Tj of the device (e.g., an LED) in its operating environment. For example, the operating environment might be a burn-in fixture, an enclosed luminaire, or any other environment where the device is installed.  In-situ Tj can be measured in two ways: directly, with the Electrical Test Method (ETM); or indirectly using the estimated thermal resistance of the heat path. Estimating Tj via thermal resistance can be risky though – if the actual Tj is incorrect, the product could fail, perform poorly, or it might be overdesigned and more costly than it needs to be. The ETM method relies on a high-duty-cycle heating current and fast transition to measurement current. A typical In-Situ LED junction temperature current waveform when using the ETM shows this fast transition. Vektrex Sample Junction Temperature Waveform There are many reasons to undertake in-situ Tj measurements. For example: Mass-marketed lighting products must include heat sinks for cooling. With more accurate Tjmeasurements, thermal resistance uncertainty budgets can be reduced, allowing heat sinks to made smaller. This reduces product cost and shipping cost. Many product failures can be traced to excessive junction temperatures or to large swings in the junction temperature. Warranty losses related to a Tj design error can exceed several hundred thousand dollars for a high-volume product. For products used in designs that are produced over many years, knowledge of the accurate Tj is helpful when comparing replacement devices to the original LED or laser. For manufacturers of LEDs and lasers, it is important to provide the most accurate measurement data possible. This data should include the precise Tj at the time of measurement. In-situ Tj measurement is a useful tool for qualifying and adjusting a design for ideal performance as it will expose the effect of small changes in the product. For example, the impact of various thermal interface materials on the heat flow out of a COB package can be measured quantitatively in just a few minutes. In-situ Tj should be compared with the manufacturer’s maximum allowed junction temperature to make sure it is below the maximum allowable Tj. Usually, designers want to see Tj 20-40% below this temperature. This is particularly important for pulsed overdrive operation. Vektrex Components Supplied for In-Situ TJ Measurement: Vektrex SMU Vektrex SMU Bias option (integrated low current measurement source) Vektrex TJ Measurement software (enhanced Control Panel) uploads data and performs y-intercept calculations Vektrex TJ Measurement Instruction Guide Vektrex Tj Utility workbook (MSExcel) to calculate k-factor and Tj Tj Change During Photometric Measurements An LED or laser heats during photometric measurements and thus the junction temperature increases. The increased Tj alters the measurement, reducing accuracy. In high-power situations, the measurement may be useless. Photometric measurement standards, such as the Illuminating Engineering Society’s LM-85, require Tj shift to be assessed and accounted for, either by altering the testing temperature, or by applying a correction to the measurement. LM-85 provides two different methods in its annexes for assessing Tj during measurements. One uses only the primary current source and the other uses both the primary and a secondary bias source. Tools to assess Tj change during photometric measurements: Vektrex SMU Vektrex SMU Bias option (integrated low current measurement source) Vektrex TJ Measurement software (enhanced Control Panel) uploads data and performs y-intercept calculations Vektrex TJ Measurement Instruction Guide Vektrex Tj Utility workbook (MSExcel) to calculate k-factor and Tj Pulsed Operation Tj Rise Assessment An LED or laser being operated with pulsed drive will experience both average and transitory heating. When designing luminaires, it is useful to know the average Tj during pulsed operation, and also the peak Tj. Average Tj can be compared with data sheet Tj values when looking at characteristics such as optical power output and wavelength. Peak Tj should be measured to ensure the device is well below the maximum allowed Tj. As discussed in the previous section, the IES LM-85 document includes procedures in its annexes for assessing Tj. This graph shows LED Tj for 1ms, 120Hz pulsed operation of a red LED. The pre-pulse, post-pulse and average temperature are shown, along with a polynomial model derived from the average Tj plot. Tools needed to assess Tj rise during pulsed operation: Vektrex SMU Vektrex SMU Bias option (integrated low current measurement source) Vektrex TJ Measurement software (enhanced Control Panel) uploads data and performs y-intercept calculations Vektrex TJ Measurement Instruction Guide Vektrex Tj Utility workbook (MSExcel) to calculate k-factor and Tj Thermal Resistance Measurement Thermal resistance is a parameter that quantifies the resistance heat sees when flowing through a path. It is always expressed as the resistance from one point to another (e.g., from junction to ambient air). The typical units are ˚C/W. LED and laser manufacturers typically provide the thermal resistance for the device itself – that is the resistance from junction to case. However, this does not include the resistance of other structures such as printed circuit boards and heat sinks. In many design situations, such as luminaire design, knowing the thermal resistance of these structures is very useful. The JEDEC JESD51-14 Transient Dual Interface Method is the best way to measure thermal resistance. This method requires a two-level current source and a voltage digitizer that can sample for long time periods. The LED or laser’s voltage is sampled after a transition and the resulting cooling curve is analyzed to calculate the thermal resistance. JEDEC provides a free software tool that does this; the SpikeSafe Control Panel application captures the data and outputs it in a file format compatible with the JEDEC tool. LED Cooling Curve Captured With SpikeSafe SMU and Control Panel Application Tools to measure thermal resistance: Vektrex SMU Vektrex SMU Bias option (integrated low current measurement source) Vektrex Thermal Resistance Software (Enhanced Control Panel) to output logarithmically spaced sample data. JEDEC software to generate structure functions and calculate thermal resistance. Heat Path Analysis Heat path analysis is similar to thermal resistance measurement, but instead of a bulk parameter representing the entire heat path, the focus of the measurement is usually a specific structure, such as the die attachment or the thermal interface material. To allow the different materials in the heat path to be identified, the cooling curve is transformed into a network model called a structure function. Structure functions for two different conditions can then be compared and the thermal characteristics of the material of interest can be inferred. The special-purpose tool that popularized structure function analysis is called the T3Ster, produced by MICRED. The calculations that the T3Ster uses to transform a cooling curve into a structure function were placed in the public domain by MICRED and JEDEC in 2010 in the form of a free analysis tool, TDIM Master. However, most labs found it was difficult to obtain cooling curves with sufficient resolution using the general-purpose instrumentation available at the time, because voltage readings were noisy. In addition, the need to change sampling intervals during the cooling time required custom software to implement logarithmic sampling. Often repetitive captures were required, meaning a single measurement could take more than an hour. Combining the captured data was also difficult. With the addition of logarithmic sampling to its true-differential digitizer, an accurate cooling curve can be collected in seconds with the SpikeSafe SMU with no custom programming. The SMU’s digitizer provides sub-millivolt detail, and it collects the curve in one capture, automatically altering its boxcar averaging on-the-fly. The log sampling feature is available in every SMU model from 500mA to 60A. The SpikeSafe Control Panel application uploads the captured log data and outputs it in a file format compatible with the JEDEC tool. Using the JEDEC tool, structure functions can then be obtained with just a few clicks after importing the Control Panel data. Structure Functions for Luxeon CZ Green LED, Generated With SpikeSafe SMU, Red: Normal, Blue: Damaged Thermal Pad read more

Integrated Thermal Control System The Vektrex Integrated Thermal Control System (ITCS) uses proprietary water-based thermal control to maintain consistent LED and laser device temperatures during high power testing applications. LED/VCSEL manufacturers and third-party test facilities standardize on ITCS chambers for their testing needs. Temperature uniformity is essential to successful high power device testing. The Vektrex Integrated Thermal Control System (ITCS) circulates water at a precise temperature in a closed-loop system for uniform thermal control in a compact footprint. With up to 10kW of power handling capability – at operating temperatures up to 150C – the ITCS chamber provides the flexibility to test numerous high power device types in a single chamber and maintain temperature uniformity within 2C. The ITCS can be purchased as a stand-alone product or with additional Vektrex components. ITCS Chamber high-capacity breakdown graphic read more

SpikeSafe DC Current Sources Vektrex SpikeSafe™ DC Current Sources provide reliable precise constant current drive.  Available in single and multiple source channel instruments, these tools are used worldwide in LED/laser diode reliability, burn-in, IESNA LM-80 test, and other current-driven applications. For applications requiring measurement, please refer to SpikeSafe Source Measure Unit.  SpikeSafe DC Current Source models supply constant current up to 60A and max compliance voltages to 400V. The high compliance voltage capability and SpikeSafe load protection allow many devices to be tested in one series circuit. This configuration is much more efficient than traditional single device circuits. The net result is lower annual operating cost and lower total cost of ownership. All models feature individual channel control, precise current, and high power density — typically 6.4kW-8kW. Use of long cables to 12m is applicable for all SpikeSafe source instruments.   Low Current Mid-Low Current Mid Current Mid-High Current High Current   500mA 4A 12.5A 30A   1A 5A 15A 40A 100mA 2A 7.5A 20A 50A 200mA 3A 10A 25A 60A Modular, Scalable SpikeSafe current sources are easily combined into systems with up to 1,024 current source channels in an electronics cabinet. Scalable, modular design enables easy system expansion for increased capacity. With a full range of SpikeSafe™ current source options, system components, chambers, fixturing, load board designs, cabling and software, Vektrex can provide the ideal testing solution for any size lab – large or small. Vektrex DC and DCP Current Source System Configuration Options Software Vektrex’s easy-to-use SpikeSafe™ Test and Reliability Software (STARS) controls and monitors sources, loads and thermal control devices during testing. With STARS, long-term reliability and burn-in tests can be automated Protects Devices Vektrex’s patented SpikeSafe™ load protection continuously monitors voltage and current patterns and instantly shuts down when anomalies are detected. Rapid shutdown preserves the failed device for analysis, and it protects other devices in the circuit. The result is lower failure counts and improved reliability statistics. Energy Efficiency SpikeSafe current sources operate at 98% conversion efficiency. This high efficiency reduces electricity usage and it minimizes the heat released into the laboratory. In addition, the current sources’ high compliance voltage capability and SpikeSafe load protection allow many devices to be tested in one series circuit. This configuration is much more efficient than traditional single device circuits. The net result is lower annual operating cost and lower total cost of ownership. Worldwide Installation Base 4 out of 5 major LED manufacturers standardize on SpikeSafe Current Sources. Over 40% of LM-80 laboratories worldwide use SpikeSafe current sources to drive their LEDs, including labs in Germany, China, USA, Korea, Taiwan, Hong Kong and Malaysia. read more

High Current SMU A Pulsed High Current SMU. Built for Power, Measurement Accuracy, and Repeatability. Vektrex’s high current SMU provides a wide range of output current to power the device under test. An integrated digitizer provides precise voltage measurement capability ensuring accurate characterization and analysis. This single instrument has broad application by supplying reliable and accurate pulsed currents to 60A while simultaneously measuring voltages to 400V. Precise pulsing with low microsecond rise times, low-jitter triggering and integrated digitizer results in more accurate and repeatable high-power LED and laser testing. For lower current SMU requirements see Spikesafe Source Measure Unit. Vektrex Precision Pulsed Current Source 60A 7.3V 100uS current pulse width 1.96us rise time   Short Pulse Test Using High Current SMU High current SMU (Source Measure Unit) delivers precise and repeatable short pulses with low microsecond rise times for more accurate and repeatable high-power LED and laser testing. Device junction heating distorts measurements, causing L-I curves to droop and shifting I-V curves. With Vektrex’s fast pulse high current SMUs, temperature-independent measurements reveal true device characteristics. Minimum pulse widths as low as 10us reduce junction temperatures for VCSEL, laser diode and other semiconductor devices. Short pulses are recommended to accurately generate IV curves, LI curves, LIV curves, and VI curves. Vektrex SMU shows comparison LI curves taken with short and long pulses. Short pulses eliminate LI droop. Continuous Output Power Continuous Power Conversion digitally transfers power from available AC or DC sources to provide sustained output power to your device.The transfer is continuous and does not rely on capacitors like older generation SMUs.  This means that it is possible to test in DC or pulsed mode, use short pulses and long pulses at low output power levels to high output power levels.   High-current SMUs provide the power needed for more accurate, efficient and repeatable measurements. Discover What You Could Not See With more high-power density LED and laser devices coming to market, there’s a gap between what can be tested with traditional source measure units and present-day engineering and production requirements. Power, pulsing and measurement requirements limit usage of previous-generation source measure units. High Current SMU close that gap by combining the speed and power needed for LED and laser testing with integrated high-speed digitizing measurement. Now you can accurately test what you previously couldn’t test, and see what you didn’t have the power to see – with remarkable repeatability. “Crazy Stable” Measurements A crazy stable measurement is perfect and unexpected.  A crazy stable measurement allows you to see something in a measurement you have not seen before and could not have seen before.  A crazy stable measurement allows discovery.  Vektrex high current SMU features sub-microsecond to low microsecond rise/fall times, programmable load tuning, and on-the-fly pulse width correction. Together these mean the device under test experiences less heating and more uniform heating. The result is unmatched measurement stability – measurements described by one beta site evaluator as “crazy stable”. Vektrex SMU shows comparison LI sweeps. Short pulses eliminate LI droop. One and Done Measurements A one and done measurement speeds production.  With high current SMU “one and done” measurement repeatability and accuracy, it is not necessary to average measurements. Test time is shortened. Excess data and data processing is reduced. False failures are eliminated improving yield and reducing the cost of test. One and done measurements. Production tester upgraded with SpikeSafe SMU improved repeatability 10X, eliminating the need for averaging. With high current SMU measurement repeatability and accuracy a 10X improvement is seen in data from this production test. True Differential Digitizer Vektrex’s SMU integrates advanced true-differential digitizer technology for accurate Vf measurements.  A digitizer is different from a DMM. With a digitizer, the common mode noise present with other measurement technologies is greatly reduced, resulting in more accurate measurements.  For example, the high-current SMU digitizer can measure small VF changes, such as a 200uV shift in a high-voltage device. The graphic below shows Vf measurements for a 1ms pulse. Note the orange trace shows Vf measurements made using Vektrex high current SMU digitizer. The blue trace was generated using a DMM.     Vektrex’s SMU uses advanced true-differential digitizer technology to produce time-aligned measurements required by measurement standards. Force Sense Selector Switch A Force Sense Selector Switch supplies integrated Connect/Disconnect and A/B Switch functions. Critical for high speed production environments, the connect/disconnect function is a true isolated switch that rapidly disconnects power to test devices eliminating control steps and speeding testing. Rapid switching times of 1ms eliminate unnecessary delays. A/B Switch functions allow secondary instruments to share load wiring and switch in and out. Many test environments include special instrumentation to support low current and reverse voltage measurements. These measurements, while important, comprise a minimum percentage of total measurements. With many specialized instruments available and currently in use, the A/B switch function simplifies system upgrades where the higher currents, faster pulsing, and better measurements available with the high current SMU are important.   What Current Do You Need? Mid-High Current High Current 10A 40A 20A 60A Vektrex developed Control Panel Software Application Vektrex easy-to-use Control Panel Software Application provides turn-key control of the high-current SMU and other instruments generally found in a test system. Control Panel’s intuitive test tools and graphic displays support common optoelectronic tests such as IV curve generation, LIV curves, LI sweeps, junction temperature, and thermal resistance measurements. With Vektrex Control Panel software application it is easy to determine the electrical characterization for unstable parts. Control Panel combined with High Current SMU provides the flexibility to validate and document device usage in end user applications. Available Drivers and Examples Standard SCPI command protocol is used for remote communication. Vektrex provides documentation and tools that make integrating our SMU into test systems easy. Python API contain all the modes and core functions for Vektrex High Current SMU. In addition, there are examples of common measurement applications like I-V sweeps, junction temperature measurements, and other measurements. Python drivers for the SpikeSafe products and detailed code samples: read more