TPS65235: adjust rise/fall time of 22-KHz signal

Ben Kuo

Part Number: TPS65235

Dear expert,

Based on the chip required, the minimum rise and fall time of 22-KHz is 5us. Customer test our TPS65235 which cannot meet this requirement.

Can we modify rise/fall time of 22-KHz signal? Please let me know if you have any idea.

Chip required

TPS65235 22-KHz waveform

-Ben

over 7 years ago

0 Sam(MPAA) Zhang over 7 years ago

TI__Mastermind 19080 points

Hi Ben,

How much output capacitance do you have on BOOST pin during the test? You may try to increase the capacitance, and see if you can get longer rise and fall time.

Tone rise and fall time is provided on Page 6 of the datasheet, as listed below,

You can also take the waveforms(Figure 28-37) on the datasheet as reference. With 22uF*2 on boost pin, Tr and Tf are just about 10us.

Regards,

Sam

0 Ben Kuo over 7 years ago in reply to Sam(MPAA) Zhang

TI__Expert 7570 points

Hi Sam,

I have 1*22uF MLCC + 1*100uF EC on BOOST pin. After add one more 22uF MLCC on BOOST, I cannot see any improvement.

Did you have any idea?

Ben

0 Sam(MPAA) Zhang over 7 years ago in reply to Ben Kuo

TI__Mastermind 19080 points

Hi Ben,

I've performed some tests on the EVM. The rise/fall time is just around 10us. Could you post your schematic here or send it to me by E-mail(sam.zhang@ti.com)? Thanks!

Please find the test waveforms below,

(VIN=12V, VLNB=13.4V, 0.4A loading, 650mV Tone)