Hello;
The comparator has an open collector transistor output designed for +/- 18Volts, so that is not going to be a problem. The Slow OC circuit charges a capacitor using a current source (approx. 330-k resistor connected to V+), on the old circuit using +5Volts, it works reliably as far as the duty cycle is 100%, but on the UHU derivatives the duty cycle is never 100% so, depending on the duty cycle, the capacitor voltage will be an asymptotic voltage almost never reaching the trigger voltage (3.33V) for the last comparator. With the modification, the integrator voltage will rise almost linearly to the 3.33 Volts and trigger reliably the output comparator and hence the current limiter. Voltage on the capacitor will never exceed 3.33 Volts because as soon as the motor current is turned off, by the limiter circuit, it will start (slowly) to discharge ( 330k resistor will be connected to approx. 0.1volts (Vce (sat))