TPS5401: Vout drops

na na78

Guru 16770 points

Part Number: TPS5401

Vout=12V and Iload=0.05A are assumed.

In customer design, when VIN is decreased around 15 V, output starts to lower than 12 V.

What do you think the cause of decreasing output level with decreasing input?

BestRegards

over 7 years ago

0 Ambreesh Tripathi over 7 years ago

TI__Expert 6860 points

Can you share the Schematic of the design . Further this is expected because of min off time restriction to refresh the charge on boot capacitor .
Refer to below app note for more details :
www.ti.com/.../slva547a.pdf

--Ambreesh

0 na na78 over 7 years ago in reply to Ambreesh Tripathi

Guru 16770 points

Hi Ambreesh

Thank you for your reply.

I attached schematics.

Could you please check if this schematics is violated for recommendation?

Input : 12.5V - 14V

Output : 12V/50mA

BestRegards

0 Ambreesh Tripathi over 7 years ago in reply to na na78

TI__Expert 6860 points

Hello ,

Please use the lower Switching frequency operation to extend the off time for the Boot charge referesh . Use 400KHz switching frequency instead of 2MHz .

The Feedback resistor is designed wrongly . Use 140K and 10K for the feedback to get 12V output .

Please follow the shared schematic of the design

Ambreesh

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TPS5401: Vout drops