TPS62825: Change of switching frequency by capacitor at Vout

Kei

Part Number: TPS62825

Hello TI team,

I have a question about switching frequency of TPS62825.
In my condition, Vin=5V, Vout=1.0V, Iout=1.0A, C2(capacitor at Vout)=2x10uF, switching frequency is about 1.8MHz.
But additional capacitors are added at Vout, which is 2x10uF, switching frequency became 2.2MHz.
Could you tell me the mechanism why switching frequency became 2.2MHz?
(The above result is not simulated value but measured value with actual device.)

Regards,
Kei

over 2 years ago

0 Sneha over 2 years ago

TI__Expert 8756 points

Hi Kei,

TPS62825 works with the DCS control topology and the switching frequency with this topology is variable and varies depending on application condition and thus, depends on the various factors circuit losses, propagation delays and the passive components. Here is an app note which explains the frequency variation with DCS control.

https://www.ti.com/lit/an/slyt646/slyt646.pdf?ts=1639479334593&ref_url=https%253A%252F%252Fwww.google.com%252F

Thanks!

Best regards

Sneha

0 Kei over 2 years ago in reply to Sneha

Intellectual 750 points

Hi Sneha,

Thank you for your answer, I understand.

Actually, I would like to use TPS62825 at about 2.2MHz.
Could you tell me whether there is any problem to use four capacitors (4 x 10uF) before feedback point ?

Regards,
Kei

+1 Sneha over 2 years ago in reply to Kei

TI__Expert 8756 points

Hi Kei,

4 x10uF is out of datasheet recommendations for the device. If you would like to use 4x 10uF caps at the output, I would recommend to check the loop stability of the device and confirm the phase margin is higher than 45degrees.

Thanks!

Best regards

Sneha

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TPS62825: Change of switching frequency by capacitor at Vout