LT8641 FB voltage higher than 0.81V

Question

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

ADIApproved · Accepted Answer

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)

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LT8641 FB voltage higher than 0.81V