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LM51231-Q1: not regulating

Part Number: LM51231-Q1

Tool/software:

I am implementing a 28V boost circuit, designed to take in 24V input. I tested on the 5123 EVM, and then in an effort to minimize risk tried to keep my design 1:1 with that, just changing the VREF set point resistors. The VCC internal regulator is outputting 5V. 

The output voltage is simply the input voltage, unregulated and passed through.

  • I have tied the MODE net to the VCC net via jumper P401.
  • I have also tied BIAS to my 24V input via P404. 
  • I have tied the SYNC line to GND via P403.

No idea where to go from here, all my components match the EVM as well, other than R407 and R409 which I sized for 28V output.