Can you help me to find the failure mode about LMR14203XKME/NOPB and/or LMR14206XMKE/NOPB?
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You can see the schematic in the picture below.
The TVS DT1 is bidirectonal TVS (the symbol is incorrect).
This power supply block is used in automotive system with alternator circuit.
In some cases I have found the following problems:
- the diode 1N4148 are opened
- the capacitor C1 are shorted or low impedance (about 2 or 3 Ohm)
- the LMR14203 have internal mosfet drain-to-source shorted
The power supply range is 10V to 32V.
What could be the issue?
Voltage spikes on power supply line?
I don't know how it is possible that the internal mosfet have drain-to-source shorted.
Thanks for your answer, Samuel.
I will investigate about load dump conditions.
However I would like to understand how it is possible to LMR14203 have the internal mosfet drain-to-source shorted.
How can that the drain-to-source channel shorting?
Can the voltage spike to VIN pin (E.g. Load Dump, ...) short the channel? I thought that cause a drain-to-source channel opened, not shorted.
We can't say for sure what kind of failure we'll see.
Voltage spike above abs max can damage the device. The abs max table sometimes says SW can exceed some value for some amount of time (or other similar exceptions) but if it's not specified as acceptable, it may damage the device.