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LTC3787EGN no start up

Category: Hardware
Product Number: LTC3787EGN


I am designing a boost converter using the LTC3787 having an output of 48V 20A from a supply of 12.5V - 16.8V. I followed the development board circuit (DC1411A) with the same component values, changing only the feedback resistors to achieve a voltage of 48V (tested and worked on the development board). On my prototype, the circuit wont start. I am seeing VIN routed to VOUT without any switching. I checked INTVCC and it is at 0V. I checked VBIAS and it is present (connected to VOUT through a 2.2R resistor). I have attached the circuit for reference. Is there any known reason why INTVCC remains 0V?

Note: I know that if the RUN pin is below a certain threshold voltage, the circuit wont start. But the potential divider for the RUN pin is supplied from INTVCC as in the development board so unless INTVCC is working, the circuit will never start. 


Edited image
[edited by: DarrenAD at 8:18 AM (GMT -5) on 9 Nov 2022]