This is a diagram of a typical application of the MSK 4201. The design Vcc voltage is +12 volts and should have a good low

ESR bypass capacitor such as a tantalum. The PWM and DISABLE signals are typically provided by some type of microprocessor

control. The PWM signal will be a TTL signal with a pulse frequency required by the system, and pulse duty cycles according to the

required direction/speed. A 0% duty cycle (continuous TTL low) will mean full voltage to the motor in one direction. A 100% duty

cycle (continuous TTL high) will mean full voltage to the motor in the other direction. A 50% duty cycle will hold the motor at 0

RPM.

Current sensing is done in this case by a 0.1 ohm sense resistor to sense current from either leg of the bridge. It is important

to make the high current traces as wide as possible to keep inductance down. The storage capacitor connected to the V+ and the

hybrid should be large enough to provide the high energy pulse without the voltage sagging too far. The storage capacitor should

be a low ESR ceramic capacitor or large polypropylene capacitor. Mount capacitor as close to the hybrid as possible. The

connection between GND and the V+ return should not be carrying any motor current. The sense resistor signal is common mode

filtered as necessary to feed the limiting circuitry for the microprocessor. This application will allow full four quadrant torque control

for a closed loop servo system.

A snubber network is usually required, due to the inductance in the power loop. It is important to design the snubber network

to suppress any positive spikes above 75V and negative spikes below -2V with respect to pin 5 (gnd) of the hybrid.

TYPICAL SYSTEM OPERATION

Rev. B 6/00

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