Hosted by Alix Paultre, the Tinker's Toolbox is the Advantage Design Group's web-based interview show where we talk about the latest technology, components, and design issues for the electronic design engineering community.
In today's podcast we talk to Mark Cejer of Keithley about high-power semiconductor testing, with an emphasis on solid state lighting (SSL). Due to the constant-current nature of SSL drivers and the nature of LEDs, proper test under a variety of conditions is essential to ensuring proper circuit performance.
Here is a link to the podcast in case the play button is not visible: Keithley Interview 
Here is an application note on their Model 2651A: Model 2651A 
Here is a release on the product:
Keithley Instruments, a world leader in advanced electrical test instruments and systems, today introduced the Model 2651A High Power System SourceMeter instrument, the latest addition to the company’s Series 2600A System SourceMeter family. Specifically designed for characterizing high power electronics, the Model 2651A provides the widest current range available in the industry. This range is critical for a variety of R&D, reliability, and production test applications, such as testing high brightness LEDs  (HBLEDs), power semiconductors, DC-DC converters, batteries, and other high power materials, components, modules, and subassemblies. To view an online product tour on the Model 2651A, visit http://keithley.acrobat.com/p50501284/ .
Like each member of the Series 2600A family, the Model 2651A offers a highly flexible, four-quadrant voltage and current source/load coupled with precision voltage and current meters. It combines the functionality of multiple instruments in a single full-rack enclosure: semiconductor characterization instrument, precision power supply, true current source , DMM, arbitrary waveform generator, V or I pulse generator , electronic load, and trigger controller, and is fully expandable into a multi-channel, tightly synchronized system via Keithley’s TSP-Link® technology. Unlike competitive solutions, which typically have limited power, measurement speed, and/or resolution, the Model 2651A can source or sink up to 2,000W of pulsed power (±40V, ±50A) or 200W of DC power (±10V@±20A, ±20V@±10A, ±40V@±5A). It can also make precise measurements of signals as low as 1pA and 100 microvolts at speeds up to one microsecond per reading.
Two Measurement Modes: Digitizing or Integrating
The Model 2651A provides a choice of digitizing or integrating measurement modes for precise characterization of both transient and steady-state behavior. Two independent analog-to-digital (A/D) converters define each mode—one for current and the other for voltage—which run simultaneously for accurate source readback without sacrificing test throughput.
The digitizing measurement mode’s 18-bit A/D converters allow capturing up to one million readings per second for continuous one-microsecond-per-point sampling, making this mode the most appropriate choice for waveform capture and measuring transient characteristics with high precision. Competing solutions must average multiple readings to produce a measurement result and often don’t allow the measurement of transient behavior.
The integrating measurement mode, based on 22-bit A/D converters, optimizes the instrument’s operation for applications that demand the highest possible measurement accuracy and resolution. This ensures precise measurements of the very low currents and voltages common in next-generation devices. All Series 2600A instruments provide integrating measurement mode operation.
Wide Dynamic Range Addresses a Broader Range of Applications
Connecting two Model 2651A units in parallel via TSP-Link expands the system’s current range from 50A to 100A. This is two-and-one-half to five times greater than the nearest competing solution. The voltage range can be expanded from 40V to 80V when two units are connected in series. The embedded Test Script Processor (TSP®) included in all Series 2600A instruments simplifies testing by allowing users to address multiple units as a single instrument so that they act in concert. The built-in trigger controller in the Model 2651A can synchronize the operation of all linked channels to within 500 nanoseconds. These capabilities of the Model 2651A provide the broadest dynamic range available in the industry, making the unit suitable for a broad variety of high current, high power test applications, including:
- Power semiconductor, HBLED, and optical device characterization and testing
- Characterization of GaN, SiC, and other compound materials and devices
- Semiconductor junction temperature characterization
- Reliability testing
- High speed, high precision digitization
- Electromigration studies
High Speed Pulsing Prevents Device Self-Heating During Test
To minimize device self-heating during tests, a common problem with high power semiconductors and materials, the Model 2651A offers high speed pulsing capabilities that allow users to source and measure pulses with high accuracy. Pulse widths from 100 microseconds to DC and duty cycles from 1 percent to 100 percent are programmable. Competing solutions are typically hampered by limited flexibility for programming the instrumentation’s duty cycle.
Powerful Test Script Development Tools
TSP Express, Keithley’s LXI-based I-V test software utility, is embedded in the instrument, so there’s no need for software installation or programming. From basic to advanced tests, TSP Express delivers device data in three easy steps: connect, configure, and collect. It also simplifies connecting instruments to allow higher pulsing levels. Results can be viewed in either graphical or tabular format and then exported to a .csv file for use with spreadsheet applications. Two other powerful software tools for creating test sequences are also provided. The Test Script Builder application supports creating, modifying, debugging, running, and managing TSP scripts. An IVI-based LabVIEW® driver simplifies integrating the Model 2651A into LabVIEW test sequences.
Effective April 2011, delivery is eight weeks after receipt of order.
For More Information
To learn more, visit the Model 2651A product page: http://www.keithley.com/products/dcac/currentvoltage/highcurrent/?mn=2651A