TPS54160 DC/DC Step-down Converter Power OFF Issue

I do not understand your issue.  Can you provide waveforms that demonstrate your problem?  Also I would like to see your exact schematic.

Hi John,

Thanks . The issue is that the output voltage of TPS54610 cannot go to ZERO Volt quickly when Vin is disconnected.

HI John,

Based on the datasheet, it is suggested to start with R2 = 10k.

 Is it possible to use below modifications?

1)  smaller values of R1 and R2, for example R1=3k9 and R2=1k?

2)  smaller values of L1 and Cout

Thanks for your prompt response. Do you mean that R2=10k is the minimum value when figuring out Vout of TPS54610 adn no other way to solve the discharging issue?

There is not a hard limit.  Very high values a are noise sensitive, very low values are additional losses that lower efficiency (especially at low output currents).  We usually recommend total resistance in the 10k to 200 k range.

Hi John,

Thanks so much for your help. Standaone TPS54160 with 10 Ohm load by disconnecting power supply to my applicaton, the discharging time was ok. On the other hand, I tried to use a switch to control the ON/OFF power supply between TPS54160 output and my application input. The problem disappeared. For this case, do you think whehter it is feasible to use a n-channel power mosfet to disconnect the power supply from TPS54160 output when Vin = 0V? Thanks.

PMOS on the output should do the trick. Be careful regarding the voltage on the gate. The output cap will then discharge through your feedback resistors.

why are high values noise sensitive？thanks！

High value feedback resistors carry very little current.

Hi John, may I have your comments on the newly inserted n-channel power mosfet from the output? Thanks.

I have not tried such a scheme, so I have no particular comment about it.  I may try it but my queue for lab work is rather full.  It may be next week until I can get to it.  Do you have a specific timing you nedd to meet?

Hi John, thanks for your kind help. The time interval between power-on and power-off from my application is around 1s. If this time interval is shorter, more buffer will be in the application. Thanks.