IST870 and IST878 Handheld Device Testers

A fast check and parameter sorting tester for a wide range of semiconductor devices. The device can be inserted into the socket in any orientation: the tester identifies pin polarity and ordering automatically, and two key presses are enough to judge whether the part is good.

The IST870 measures leakage with a fixed 30 V bias applied to the corresponding pins while the device is off, with a highly sensitive current meter in series. Ranging is fully automatic across six ranges from 0 nA to 40 mA, with a resolution down to 1 nA.

Leakage is one of the parameters that most affects circuit performance and service life. A part that reads in the microamp or milliamp range where a known good part reads under 50 nA can be taken as degenerated or breaking down.

Besides transistors, diodes, MOSFETs and thyristors, the tester runs a dynamic functional test with a 300 µs pulse and then measures leakage automatically. Zener diodes and positive or negative regulators are measured for output voltage in the same way.

Devices already soldered on a board can be checked in circuit with the three point probe, which suits surface mount parts.

The difference between the two models is range: the IST870 shows whether the device has a leakage problem, while the IST878 measures up to the breakdown voltage or leakage limit of a good part.