I'm using Analog Devices ADP160ACBZ-2.75-R7 LDO in several products.
Recently in a certain product, in two units which succesfully passed all regular tests, I noticed that the current consumption is much too high (50mA instead of 10uA). After a failure invetigation it turned out that the extra current is related to the LDO.
Here are some facts from the failure analysis:
1.The LDO was observed as the cause to the extra current consumption after using a thermal imaging in which the LDO was the only "HOT SPOT".
2. The system power source is a power supply with voltag range of 3V - 4.2V.
3. The LDO output voltage during the failure was OK (2.76V).
4. During the regular tests (before the failure occured) the circuit worked OK and current consumption was OK too (~10uA).
5. After replacing the LDO in one of the failed units the circuit returned to work as expected with current consumption of 10uA.
6. In the second failed unit the LDO was isoltaed from all other circuitry by taking out series passive components. The LDO alone was powered by a 4V supply and still consumed around 50mA with the output voltage OK.
7. I measured the input imedance between Vin and GND in a good unit and in a failed unit. In a good unit the impedance is around 1.6MOHM; in the failed unit the impedance is around 1.6KOHM.
The LDO component reel details:
Date Code: 1226
LOT ID: P048713.8
Thanks in advance,
Based from your observations, looks like the VIN has been damage that's why the device is consuming more current than expected. It may be due to an over-voltage or ESD that partially damage the protection diodes that caused the input impedance to decrease. In effect, this produced a less resistive path that current may flow from VIN to GND. You may check the supply of the ADP160 if overshoot occurs.