NPM1100 PMIC damage when powering external TLV320AIC3104 codec from NRF5340 Audio DK 1.8V rail

RE: NPM1100 PMIC damage when powering external TLV320AIC3104 codec from NRF5340 Audio DK 1.8V rail

Kazi Afroza Sultana — Mon, 01 Dec 2025 13:35:08 GMT

Hello,

Backfeeding occurs when the voltage at the PMIC’s output (VOUTB) is driven higher than the PMIC’s own output voltage, typically by an external source or large capacitor. nPM1100’s buck cannot sink that much current and has internal MOSFET/body-diode paths that will conduct those reverse currents into internal nodes, potentially overstressing gate drivers, clamp diodes or internal FETs — and causing permanent damage.

Can you tell a bit detail how you have connected the external codec to the audio DK?

RE: NPM1100 PMIC damage when powering external TLV320AIC3104 codec from NRF5340 Audio DK 1.8V rail

Falguni — Wed, 26 Nov 2025 17:36:21 GMT

Will you please explain how backfeeding can damge my pmic , also tell that how backfeeding will be there if my source 1v8 is supplied from pmic output to the tlv320aic3104 1v8 pin .

RE: NPM1100 PMIC damage when powering external TLV320AIC3104 codec from NRF5340 Audio DK 1.8V rail

Kazi Afroza Sultana — Wed, 26 Nov 2025 12:31:52 GMT

Hello,

1. This is difficult to say based on just this information. If you have some current/voltage waveform of the startup and schematic can share with us. That would be helpful.

2. No.

3. Yes, that is possible. In hysteretic mode, the buck converter can not sink current, so if there is any backfeeding to the output of the buck the voltage starts rising.

4. We have not designed AP7346D-3318 regulator. But we are comparing LDO to buck, so we don't think this is comparable.

5. No.

The nPM1100’s 1.8 V rail is not intended for significant external loading beyond 150 mA. Overloading or improper connection of external loads can damage the PMIC.