On brake driver (HW) implementation

Hi Guys,
I’m looking at the schematics/implementation of the brake resistor driver on the odrive (V3.5). It uses a fully featured half-bridge driver. I’m no motor control guru for sure, but I cannot help but wonder, why is a half bridge driver used? Shouldn’t just a resistor tied to VDD and a low side switch be enough? It would also support a 100% duty cycle, which the half bridge does not. In case of odrive, the bottom two mosfets serve no purpose, apart from bringing the switch node down to 0V, so that the bootstrap capacitor of the half bridge driver can recharge. Or is there something I’m not getting right?

Thanks for any input; I like the simplicity of odrive-s hardware, but this brake circuitry really bothers me.


You’re right, the bottom two mosfets are not used. I’m not sure why it was done like that, but it is.