I'm trying to build a portable speaker. I want to use an arduino to handle several tasks. The speaker uses a 6s Lipo ~24v as power source. An LDO the AP7381 has been selected as power source for the arduino.
The AP7381 provides the required 5V on a wide input range while having a low quiescent current which is important for the battery life. The idea is to have a very low power consumption when the speaker is off and the arduino sleeping drawing less than 10uA.
I want to test the power source with the arduino before I blow up multiple components.
The datasheet of the AP7381 recommends to use a 1uF input and a 2.2uF output capacitor. I use ceramic capacitors.
The isolated test for the power source of the arduino has failed several times now with a destroyed LDO but I cannot see the problem in my schematic.
(I suspected reverse current on the LDO to be a problem which is why I added the diode but it didn't help.)
I have tried the following:
- Using a step down converter -> works
- Using the AP7381 without capacitors -> works (not a good idea I guess)
- Using a diode to prevent reverse current (as seen on the schematic) -> fails
- Using no diode -> fails
What could cause the LDO to blow in this small setup?