Panasonic UF-5500 Service Manual page 42

UF-5500 / 4500
6.7.2.2. OCP (Over Current Protection) circuit
1. Functions
By parts failure or other reason, if Vref voltage exceeds 0.9V, extreme current is supplied to the motor. This may cause motor
over heat and damage.
To prevent this problem, over current protection circuit is provided.
If Vref voltage becomes over 0.9V, Q522 or Q700 turns on. Then PS signal (pin20 of motor driver) becomes "L" and motor
driver stops output the motor current.
2. Circuit Diagram
Refer to the circuit diagram in Motor current control circuit (P.41).
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