TPS65251: How Softstart Capacitor will affect the Compensation circuit Parameters value

JAYAKRISHNAKUMAR S

Part Number: TPS65251

Hii,

The output of the TPS65251 Buck regulator (3.3V) is stable under No load and Hotplugin condition and not coming stable under load condition due to an increase in delay (75 mS)of the circuit by replacing the soft-start Capacitor. Is there any necessary to change the Compensation Circuit Parameters? Please share me the related Documents and calculations if any.

over 5 years ago

0 Zhao Ma over 5 years ago

TI__Genius 15135 points

Hi, JAYA

1. TPS65251 has a limitation on soft start timer: Tss should be smaller than 9mS, suggest Css <=33nF.

2. Could you send me the schematic?

0 JAYAKRISHNAKUMAR S over 5 years ago in reply to Zhao Ma

Prodigy 160 points

Hii,

Thanks for the reply.

I will share the schematics.

Another Doubt, Can u please tell me how to calculate the external compensation (Rc,Cc and Croll)?

Please share me the necessary documents in a very clear manner.

SCH_EPCB-6030-H-00-A1.pdf

0 Zhao Ma over 5 years ago in reply to JAYAKRISHNAKUMAR S

TI__Genius 15135 points

Hi, JAYA

1. For the compensation calculation, you can refer the "9.2.2.1 Loop Compensation Circuit" in DS.

2. As a best practice, you can use the compensation circuit directly in EVM schematic.

Power management

Power management forum

TPS65251: How Softstart Capacitor will affect the Compensation circuit Parameters value