Not enough current coming out of BMS1040ABT digital output

4 months 2 weeks ago #29535472 by jinbae9875
When I connect a buzzer between the open drain output Dout1 and Vcc, I only get around 3 mA of current through the buzzer. However, according to the documentation:
"changed Vcc input of user connector to 5V out, with 15mA current limitation in order to drive directly the wakeup through an external mechanical switch."
the limit should be around 15mA. Is 3 mA normal for my use case? I'm getting around 30 mA when I connect the buzzer to four AA batteries and the battery connected to the BMS is a 6 cell 16mAh battery. Is there a way to bring that current up so that I can actually hear the buzzer?

 

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2 months 1 week ago #29535506 by sr
In the subject of this post you're mentioning "not enough current coming out of the BMS1040ABT digital output". In our experience, the digital output can sink more current, but the VCC here is not meant to power the buzzer. So the VCC might be your limitation, not the digital output. You might be able to get the buzzer going by powering it (through a fuse) from the pack +, assuming that your 6 cells have a voltage that is compatible with your buzzer and the maximum handled by the digital output.

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