TPS63060EVM-619: Vout decrease problem on external soft start circuit

Satoshi

Guru 19645 points

Part Number: TPS63060EVM-619

When TPS63060EVM add the soft start circuit by application note slva533(10nF and schottky), large load condition occur Vout dropped.

Please let me know about the reason and measure for Vout decrease.

【Additional information】

・Circuit is based on default TPS63060EVM setting, R2 is only changed 110kΩ to 100kΩ (5.5Vout).

・Iout: 10mA and 60mA are normal 5.5Vout, but 250mA and 500mA are occur Vout drop.

・ Vout drop range is depend on Vin.

・Schottky is tried two type below;

　・D1NS4

https://docs.rs-online.com/a993/0900766b80fd9a58.pdf

　・RB521S-30

https://fscdn.rohm.com/en/products/databook/datasheet-nrnd/discrete/diode/schottky_barrier/rb521s-30.pdf

Best regards,

Satoshi

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Satoshi,

I would suggest a general diode instead schottky diode, which normally has large leakage current, for this application. also the additional circuit should be very closed to the FB pin to avoid noise coupling.

could you share the VIN, VOUT, also inductor current waveform if possible when observing the issue?

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

TI__Mastermind 46905 points

Hi Satoshi,

I closed the post assuming the issue is solved. if not, just reply below

Power management

Power management forum

TPS63060EVM-619: Vout decrease problem on external soft start circuit