TPS61178EVM-792: EVM test questions on Vout drop and ripple

Polly Chung1

Part Number: TPS61178EVM-792

Dear team,

My customer has test our EVM, but they have some questions. Could you please help them? By the way, they change our EVM to 12Vout.

1. There is 8.94V drop when they did load transient from no load to 3A. Is there any suggestions to reduce Vout drop?

2. The output ripple is around 1V. Is there any suggestions to reduce output ripple?

Below are waveforms for your reference. Thank you.

Best Regards,

Polly Chung

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Polly,

1. to improve the transient performance, please reduce the current limit resistor to 51K. also increase the output capacitor, what is target voltage drops?

if the load transient is critical from 0 A to 3A, we may need to consider forced PWM device TPS611781.

2. The high stable ripple is caused by the probe setup and the noise coupling into the oscilloscope, not the real performance.

0 Jasper Li over 5 years ago in reply to Jasper Li

TI__Mastermind 46905 points

Hi Polly,

I closed the post as no further feedback. just reply below if there is question

0 Polly Chung1 over 5 years ago in reply to Jasper Li

TI__Intellectual 2110 points

Dear Jasper,

My customer has changed Rlimit to 51kohms, but Vdrop did not get improved. Do you have any other suggestion? Thank you.

Best Regards,

Polly

0 Jasper Li over 5 years ago in reply to Polly Chung1

TI__Mastermind 46905 points

Hi Polly,

please try to increase the output capacitor.

you also email me that customer requires 5A output current, which may need a controller device TPS4306x. So I close this post.

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TPS61178EVM-792: EVM test questions on Vout drop and ripple