Window comparators enable device testing without bus isolation relays

The testing of devices with large input or output voltage swing requirements, such as flash memory wafers that may use tester signals up to 15V, typically requires discrete isolation relays to disconnect test cards from the test bus when they are not in use. Intersil’s single-chip window comparators save space by eliminating the need for isolation relays, and save time by removing the set-up associated with the card isolation function, streamlining the testing process.
Intersil’s ISL55141/2/3 products utilise a window comparator architecture on-chip rather than the single comparator architectures of competing devices. This allows significantly more circuit integration on test cards, freeing up space for other tester functionality.
In the devices, two reference voltages can be used to establish high and low specification points for a device output signal to be tested. In this way, it is possible to perform high-speed digital performance testing of semiconductor devices under a variety of load conditions.
The ISL55141/2/3 provide a wide input voltage range and high input signal bandwidth to enhance test coverage, while the low (50mV) input offset voltage enables very accurate signal testing. High input impedance across a wide input range can eliminate test bus isolation relays, resulting in lower product cost and more free board space.
The family of products is simple to work with. In a typical application, the comparator is connected to a test bus. It receives static or dynamic signals from a device under test (DUT), then compares these signals to pre-defined reference voltage levels, and provides digital output to indicate that the reference thresholds have been crossed. These outputs are then transmitted to the test controller at signal levels that can be set by the tester designer. This allows the tester to interface with a wide range of logic families.
All three devices include a power-down mode with less than 10uA of current draw. The ISL55141 includes a single window comparator, while the ISL55142 has two and the ISL55143 provides four. All three versions can accept input signals up to 65Mhz in frequency.
Other key features of the family of devices include an 18V signal range, low skew and 8ns minimum pulse width, user-selectable logic level output, high input signal bandwidth, and a bipolar input signal handling capability.
Target applications for the devices include flash memory wafer testers, burn-in testers, low-cost ATE (automated test equipment), and LCD panel testing. The ISL55141/2/3 family is available now in QFN and TSSOP packages.