I am using the circuit in the second picture, which clearly uses a diode. (Found here) However the TIP120 data sheet transistor already has a diode in the schematic symbol. Do I need to add another diode (like in the schematic) or should I remove the diode in the circuit, as the transistor has one built in?
The datasheet does not say about the internal diode ratings, so external protection is a good idea when connecting to loads that may generate negative voltage undershoots. But what is important when driving inductive loads is that they can generate positive overshoots that can break the transistor, so there is even more need for a diode over the motor.
