What does the diagnostic function available with low-voltage IPDs do?

Operation example of diagnostic function (high-side switch)
Figure 1 Operation example of diagnostic function (high-side switch)

The diagnostic function drives the DIAG terminal High or Low in the event of an abnormal condition being detected.

It signals an abnormal condition when overcurrent protection,thermal shutdown, or open-load detection (i.e., high-impedance output) is tripped. It is possible to identify an abnormal condition in an IPD by processing the input and diagnostic output signals with a microcontroller or a logic circuit.

Example of the operating truth table of a low-voltage IPD
Operating Mode Input Signal VIN Output Voltage
VOUT
 Output MOSFET State Diagnostic Output VDIAG Note
Normal operation L L Off L -
H H On H
Shorted load / short to ground (overcurrent condition) L L Off L It is possible to determine whether an IPD has a shorted load (overcurrent condition) or a thermal shutdown condition by processing the input and diagnostic output signals with a microcontroller or a logic circuit.
H L On (current limited) L
Thermal shutdown condition L L Off L
H L Off L
Open load / broken wire L H Off H -
H H On H

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