Programmable power supplies reduce costs in automated test

February 19, 2014 // By Graham Prophet
Two multi-channel power supplies with GPIB interfaces offer, according to makers Keithley, greater output accuracy at lower prices. The new models address the need for greater control and communication flexibility in both R&D and production test applications, where GPIB interfaces continue to be used.

The Model 2230G-30-1 power supply provides two output channels, typically used for powering analogue circuits, with each channel capable of outputting up to 30V/1.5A/45W, plus a 6V/5A/30W output channel, typically used for powering digital circuits; 25V/1A limits are more common, the company says. The Model 2220G-30-1 power supply provides two output channels, each capable of outputting up to 30V/1.5A/45W. These maximum output levels, combined with voltage setting and reading resolution of 1mV and current setting and reading resolution of 1 mA, allow generating a wider range of output power and reading a wider range of load currents with high precision.

Basic voltage setting accuracy and voltage readback accuracy is 0.03% for each output channel (0.05% on alternative units); remote sense terminals on each channel of the new power supplies compensate for voltage drops in the power supply leads to ensure that the correct voltage is delivered to the load terminals of the DUT, enhancing overall system accuracy. They also offer superior basic current setting and readback accuracy (0.10% versus the market leader’s 0.15% accuracy) and less than 3mVp-p ripple and noise to ensure high quality load current measurements.

Each output channel is completely isolated, which allows the new power supplies to power two isolated circuits with different reference points, eliminating the need for a second power supply. Each channel can also be turned on or off independently, so the power supplies can be used to power up a circuit that requires turning on multiple voltage levels in a specified time sequence. A programmable timer allows setting up a test to run unattended, turning off the outputs after a specified interval.

For applications that require supplying more than 30V or 1.5A, the new power supplies’ 30V outputs can be combined in a variety of configurations, such as being wired in series to produce a 60V output with a maximum current output of 1.5A or wired in parallel to produce a 3A