LP5912 Noise Spur at 300KHz

TIguru

Other Parts Discussed in Thread: LP5912

Hi,

I’m looking at TI's LP5912DRV low-noise linear regulator. I notice that, under load, the noise rises between 100kHz and 1MHz, with the peak at roughly 300KHz.

What is the source of this noise?

Is there a recommended method to suppress this?

over 7 years ago

0 LeonardEllis over 7 years ago

TI__Guru 71516 points

guru -

This App Note explains the source of the noise (cursory, not intense detail) and proper ways to measure: http://www.ti.com/lit/wp/slyy076/slyy076.pdf .

~Leonard

0 Donald Jones over 7 years ago

TI__Mastermind 22610 points

Feedback from a person familiar with the LP5912 design :

" ... For LP5912 500mA load condition, the peak noise at 300KHz comes from power pass FET. Because 300KHz is out of the bandwidth of LP5912, the noise will not be depressed by the loop gain (because loop gain is less than one). You may try to push the bandwidth to higher frequency by reducing output capacitor to push the peak noise frequency higher. But this may have negative effect in regards to the stability and load transient performance. Over all, I don’t think you can improve the noise much by adjusting external components.... "

0 TIguru over 7 years ago in reply to Donald Jones

Expert 1430 points

Donald,

Thank you for the additional detail. I appreciate TI's help on this.

Power management

Power management forum

LP5912 Noise Spur at 300KHz