TPS548A28: Switching Frequency out of datasheet specification on customer/user board

hu kevin

Prodigy 20 points

Part Number: TPS548A28

Tool/software:

TPS548A28 datasheet figure 8-4 show Switching Frequency as flow:

TPS548A28 design summary on customer/user Board：

input：12.31V

output：2.5V @ 6.0A

inductor：0.56uH

setting RMODE = 30.1 kΩ to AGND

Test SW waveform as flow, switching frequency is between 872Khz ~ 905Khz, which is out of datasheet specification .

Quenstion:

1、 Is Switching Frequency on customer/user board normal or abnormal?

2、if abnormal, how to fix it?

2 months ago

0 Ryan Chen 2 months ago

TI__Genius 15147 points

Hi Kevin,

Can you please share the schematic?

Best,

Ryan

0 hu kevin 2 months ago in reply to Ryan Chen

Prodigy 20 points

sended schematic by TI E2E email.

thanks

0 Ryan Chen 2 months ago in reply to hu kevin

TI__Genius 15147 points

Hi Kevin,

I don't think I see it. I sent you a friend request on E2E private message so you can send your schematic through there.

Best,

Ryan

0 hu kevin 2 months ago in reply to Ryan Chen

Prodigy 20 points

Fail to receiver any request at E2E message

0 Ryan Chen 2 months ago in reply to hu kevin

TI__Genius 15147 points

Hi Kevin,

Looking at your schematic, one thing is that if you are not using the remote sense pin VSNS-, VSNS- should be connected to AGND instead of PGND. R1320 should be connected to AGND instead of PGND.

Otherwise, the TPS548A28 is DCAP-3 so having variation on SW is normal. Can you send a waveform of the output voltage ripple? If there is nothing wrong with the output ripple waveform then it is okay.

Best,

Ryan