New-Tech Europe Magazine | July 2016 | Digital edition

pulses, DMMs offer much greater precision when making voltage measurements. A power source, a DMM, and an oscilloscope might be required to make all the necessary measurements. A source measure unit (SMU) instrument could be another possible option for this application. They can measure very low currents (down to picoamps or less) accurately; unfortunately, they are not typically designed to capture narrow pulses. Also, SMUs are generally low power instruments and so might not have sufficient total power to deliver the peak current necessary to characterize a device that draws a large amount of peak power. In addition, because of their extraordinary sensitivity, SMU instruments can be relatively expensive solutions for testing low-

Figure 3. Keithley’s Series 2280S Power Supplies can characterize small load currents with 10nA resolution and measure up to 6A very accurately. Four load current measurement ranges—10A, 1A, 100mA, and 10mA—allow measuring both full load currents and standby/sleep mode currents with 6 1/2 digit resolution. It can also capture dynamic load currents as short as 140μs.

Figure 4. As a device is powered up during characterization or production testing, the load current increases as it cycles through the sleep, standby, and active modes. To characterize this start-up sequence, the test setup must be capable of making fast measurements synchronized to the device’s state changes.

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