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BQ24600: Vref pin greater than 3.3V

Erin

Prodigy 20 points

Part Number: BQ24600

Hi,

I am having an issue using the BQ24600 IC where the Vref pin is at 3.6V (and sometimes reaches 3.9V) instead of 3.3V. The circuit is designed to have an input voltage of 24V and output 13.8V with a maximum output current of 5.3A. I have attached pictures of my schematic and layout below. The only other input to the circuit is control for the CE pin, which sets the pin to either 5V or GND, depending on other inputs to the board.

Thanks for any advice!

Erin

over 4 years ago

+1 Michael Emanuel35 over 4 years ago

TI__Mastermind 41805 points

Dear Erin,

Do you have a 1 uF capacitor attached to VREF? This serves as a decoupling capacitor for VREF and is required.

Also, is your output tied to the VFB pin? It looks R28 and C25 are floating, but they need to be connected to the battery for charge voltage sensing.

Thanks,

Mike Emanuel

Please click "Resolved" if this answered your question.

0 Erin over 4 years ago in reply to Michael Emanuel35

Prodigy 20 points

Thanks, adding a decoupling capacitor to VREF did bring it to 3.3V.