Post Go back to editing

LT8641 FB voltage higher than 0.81V

Category: Hardware
Product Number: LT8641IUDC#PBF

Hi, 

I'm using the LT8641 to step down from 5V to 1.2V. 

My top feedback resistor is 392K, 0.1% and bottom feedback resistor is 806K, 0.1%. I am seeing 1.29V at the input and Vfb is 0.871V, as opposed to 0.81V. This is at no load. 

What could cause this to happen? 

Thank you

Parents
  • From the datasheet, the FB voltage is a function of the VOUT and the voltage divider. The regulation can be affected by noises getting into the FB and GND pin, noise coupled through the capacitors and ripple voltages. Good layout and component selection can minimize these. You can check for layout considerations and component selection on the Applications Information section of the datasheet.

    Regards,

    Nino

Reply
  • From the datasheet, the FB voltage is a function of the VOUT and the voltage divider. The regulation can be affected by noises getting into the FB and GND pin, noise coupled through the capacitors and ripple voltages. Good layout and component selection can minimize these. You can check for layout considerations and component selection on the Applications Information section of the datasheet.

    Regards,

    Nino

Children in reply to AnthonyT0417

Bypass caps are used to minimize the loop to reduce the noise. If the noise is severe enough, it might damage the part or make it not work properly or both. I highly suggest following the datasheet recommendations and guidelines.

Regards,

Jhun