TPS40100：输出最小建立时间无法查询；减小ss（softstart）电容无法改变Vout的建立时间

cao zy

Part Number: TPS40100

TPS40100芯片数据表无法查询到最小的输出建立时间;目前遇到一个问题，当在芯片ss（softstart）引脚对GND加100nF电容时，Vout建立时间约4ms;当将ss引脚对GND电容容量减小，例如47nF、10nF等值时，Vout建立时间仍然无法改变，想请教贵司是什么原因？

9 months ago

0 Yuchang Zhang 9 months ago

TI__Mastermind 18510 points

This part supported by US team, please translate to English and re-submit the thread. this thread will be closed.

Yuchang

0 Nancy Zhang 9 months ago in reply to Yuchang Zhang

TI__Mastermind 46930 points

Hi Cao,

Did you use tracking in your application? Could you send us the schematic?

Thanks,

Nancy

0 cao zy 9 months ago in reply to Nancy Zhang

Prodigy 10 points

I used the tracking function. The schematic is shown in the picture.

Thank you for your answer.

Cao.zy

0 Peter James Miller 9 months ago in reply to cao zy

TI__Guru 50635 points

cao zy

The TPS40100 start-up will track the slower of the SS defined soft-start time or the tracking input. Check the rise-time on your TRKIN and TRKOUT if you are not seeing a faster start-up with reduced SS capacitance.

0 Nancy Zhang 9 months ago in reply to cao zy

TI__Mastermind 46930 points

Hi Cao,

Please refer to datasheet page 23 " Interaction between Soft-start and Tracking Startup" section. When you used tracking to control the start up, the soft-start should not be set to a short time and the soft start ramp must be within the capability of the tracking loop to override.

Hope this helps,

Thanks,

Nancy

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TPS40100：输出最小建立时间无法查询；减小ss（softstart）电容无法改变Vout的建立时间