TPS65130: Negative output inductor buzzing

Jian Wei Lai

Part Number: TPS65130

Tool/software:

The design uses the TPS65130 to convert +5V input to ±15V outputs. During testing, we observed that the inductor on the -15V output emits a buzzing noise.

This noise disappears if FB5 is disconnected, the -15V output is left without a load, or if ENN is pulled low to disable the negative voltage output.

Increasing the load to 30mA did not alleviate the problem. Do you have any recommendations? Attached are the voltage and current waveforms for inductor L4.

SCI-RN88_ 07_POWER_15V_20240612.pdf SCI-RN88 _A02-240819_TPS65130_TPS7A3901.brd

over 1 year ago

0 Patrick Yao over 1 year ago

TI__Mastermind 35590 points

Hi Jianwei,

Have you enabled the PSP and PSN?

Patrick

0 Jian Wei Lai over 1 year ago in reply to Patrick Yao

Prodigy 130 points

Hi Patrick,

Yes, both PSP and PSN are enabled. We tried disabling PSN, but it had no effect.

Woody

0 Patrick Yao over 1 year ago in reply to Jian Wei Lai

TI__Mastermind 35590 points

Hi Woody,

View the inductor current, seems there is no audible range frequency oscillation. Have you confirmed whether the noise is really from the inductor?

Patrick

0 Jian Wei Lai over 1 year ago in reply to Patrick Yao

Prodigy 130 points

Hi Patrick,

Sorry for the late reply. We spent some time confirming our setup. Our configuration is as follows: +5V is converted to +/-15V using TPS65130, and then +/-15V is converted to +/-14V by TPS7A3901DSCR LDO. The -14V is supplied only to the ADC. We have conducted the following tests and suspect that the issue might be related to the LDO. Please provide suggestions:

The TPS7A3901DSCR LDO -14V output produces noise even without a load.
Supplying -15V from TPS65130 directly to the ADC IC (bypassing the LDO) eliminates the noise issue.

Woody