● To test the lower diode,which is connected to VSS,use the PMU to force a negative current of approximately-100μA.Set the lower test limit of the PMU to fail if the measured result is less than-1.5V to detect an open . Set the upper PMU limit to fail if the measured result is greater than -0.2V to detect a short. This test method is used to test signal pins (inputs an outputs) but not power pins such as VDD or VSS.
● Power and ground pins may also be tested for an open condition, but their structure is different from that of a signal pin. Test the power pins, observe the measured value on a good device, and set the test limits accordingly.