DRV8870: DRV8870 reverse current protection and Ivm value

Hey Brian,

Brian Chan said:

1. do H bridge need a reverse current protection? or it default need a reverse current so VM need to handle reverse current?

No, our motor drivers can handle the reverse current from the motor back-EMF.  However, reverse voltage can damage our device.  The bulk capacitance should be chosen to be large enough to keep the voltage within the device spec.  

Brian Chan said:

2. why Ivm here is only mA scale? because it look like same path with output current.

The I_VM spec is for the current consumed on VM without a motor connected, basically the losses that occur unrelated to a motor.  Basically the active mode current losses.  This is important to show customer they should use sleep mode when not actively driving the motor

When driving the motor then I_OCP will limit the current to a given amount of amps, and the current draw will depend on the load. 

Brian Chan said:

could you also check the motor driver can match below spec?

lr4-2600-0a.pdf

Looks like that's a 12V, 100mA RMS / 2A peak current motor. Yes, that will be no problem for DRV8870.  However, our newer device DRV8231 is a better fit for the voltage and current levels, it will be priced better than DRV8870 and the DRV8231A has integrated current sensing which can further reduce PCB size and BOM cost.

Best,

Jacob