Placement of protection diode on motors with current sense?

Thread Starter

Barnaby Walters

Joined Mar 2, 2011
Hi there,

I've just started looking into current sense chips, in preparation for building a robot that navigates using no sensors apart from current sense resistors in series with the motors, and probably a LTC 2991 for the current sensing.

What I'm wondering is whether or not I should be protecting the current sense circuits with a diode in the same fashion I would protect a transistor. I'll be using a H Bridge, with the current sense resistor either between Vcc and the sources of the P channel FETs or between the source of the N Channel enable FET and gnd.

The LTC2991 can only handle input voltages of up to Vcc, which will be regulated 5v for it, but unregulated 7.4v for the motor. Obviously I need to attenuate the signal with voltage dividers, but do I need some kind of back EMF protection for the current sense resistor?

Thanks a lot,