LMR14050-Q1: Power management forum

Rod Brick

Part Number: LMR14050-Q1
Other Parts Discussed in Thread: LMR14050

TI's SNVA021C suggests a "feed forward" low value ceramic capacitor (I assume 0.1 to 0,01uF) between SW and FB pins is helpful. Is this significant or critical for the LMR14050?

over 5 years ago

0 Iven Su over 5 years ago

TI__Expert 8245 points

Hi,

The description is not found in . Please double check it. Thanks.

0 Rod Brick over 5 years ago in reply to Iven Su

Intellectual 580 points

In 3. Filter Capacitors (pretty obscure, I admit!)

"Some designs require the use of a feed-forward capacitor connected from the
output to the feedback pin as well, usually for stability reasons."

0 Iven Su over 5 years ago in reply to Rod Brick

TI__Expert 8245 points

Hi,

I don't think it's necessary for LMR14050 unless you find the phase margin and bandwidth in your application is not enough.

0 Rod Brick over 5 years ago in reply to Iven Su

Intellectual 580 points

Thanks

0 Rod Brick over 5 years ago in reply to Iven Su

Intellectual 580 points

Iven, an observation: WEBENCH for the LMR14050 puts in a 220pF capacitor, but it is not obvious why, especially since the LMR14050 has internal compensation. It does increase the phase margin but it is always withing limits. It makes a big difference in the crossover frequency but I don't know about bandwidth. Side question: why would you need to increase the bandwidth? I thought the bandwidth can hardly be too low. Is bandwidth related to crossover frequency?

Thanks for your time.