TPS82140: About FB resistance setting

user3669088

Part Number: TPS82140

The data sheet states that R2 should not exceed 100 kohm for high efficiency.
What is the recommended value for R2?
VOUT = 1.2V is planned.

0 Ruby Li over 4 years ago

Our US team will feedback to you after holiday. Thanks.

Thanks,

Ruby

0 Andrew Xiong over 4 years ago

Hi,

Our colleague responsible for this device is in holiday. But with our Webench designer tool, you can get the recommended design then.

Regards,

Andrew

0 Tahar Allag over 4 years ago in reply to Andrew Xiong

Hello,

For 1.2V, R1 can be 49.9K and R2 can be 100K. The following equation can be used to calculate R1 and R2.

VOUT=VFB*(1+R1/R2)

VFB=0.8V

Thanks

Tahar

0 user3669088 over 4 years ago in reply to Tahar Allag

Thank you for your answer.

What are the possible problems if R2 exceeds 100kohm?

0 Jean Picard over 4 years ago in reply to user3669088

The device will still work. However, as the FB network impedance increases, the impact of FB leakage current on Vout accuracy will increase too.

The statement about noise is more of a general system-level recommendation.

Jean

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