TPS61169: Regarding unstable switching

Kaji@PAN

Part Number: TPS61169

Hello,

I asked about the unstable switching of TPS61169 in the thread below.
I changed the output capacitor from 4.7uF to 1uF and measured it.
The result is shown below. It's worse than before the change.
I haven't changed the inductor yet, but is there any way to stabilize the switching other than changing the capacitor or inductor?

Best regards,

https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1271190/tps61169-switching-is-unstable

7 months ago

0 Patrick Yao 7 months ago

TI__Mastermind 20010 points

Hi Kaji,

Could you please send me the layout for double checking. You can send me the layout through private message if you have confidential concern, thanks.

Patrick

0 Kaji@PAN 6 months ago in reply to Patrick Yao

Mastermind 7035 points

Thank you for your reply.
I have two additional questions.
(Question 1)
Currently, I am using an inductor of 10uH, but the data sheet below recommends 4.7uH if the input voltage is 5V or higher.
I don't really understand the reason, so please explain it to me.
Does it affect stability?
(Question 2)
There is no description of MIN_ON TIME or MIN_OFF TIME in the electrical characteristics of the datasheet.
Please let me know if there are any regulations. I'm concerned about whether that value is having an impact.
Best regards,

0 Jared Zhou 6 months ago in reply to Kaji@PAN

TI__Genius 9650 points

Hi Kaji,

Our expert is out of office and will reply to your questions once coming back. Thanks for your patience.

BR, Jared

0 Kaji@PAN 6 months ago in reply to Jared Zhou

Mastermind 7035 points

Hello,
How is the progress?
Best regards,

+1 Patrick Yao 6 months ago in reply to Kaji@PAN

TI__Mastermind 20010 points

Hi Kaji,

Sorry for the late, unfortunately we don't have data related to min_on time and min_off time. The inductance will influence the loop stability, and Vin will also influence the switch duty cycle which is also an important parameter in control loop. So please follow the guide in datasheet. Thanks

Patrick

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TPS61169: Regarding unstable switching