Slew rate circuit for high side driver for a polyphase DC motor

A high side driver circuit which controls the turnoff slew rate to an inductor of a motor that is selectively connected between a supply voltage on a high side and a reference potential on a low side, comprising:

• a power transistor having a current control path connected in series between the high side of the inductor and the supply voltage to connect selectively said inductor to said supply voltage;
• a switch;
• a capacitor connected between a non-inverting input of an amplifier and the reference potential, said capacitor being switchably connected by said switch to a supply voltage to charge said capacitor when said power transistor is to be turned-on and to allow said capacitor to discharge when said power transistor is to be turned-off;
• a constant current source connected in parallel with the capacitor for discharging the capacitor at a constant rate;
• and an amplifier having a non-inverting input connected to said capacitor and having an output connected to a control element of said power transistor to compare a voltage on said capacitor with a voltage on the high side of said inductor.