Motorola Corporation

Jeffrey G Mansmann

Gary V Fay

Keith M Wellnitz

Philip W McEntarfer

An integrated circuit power timer having a power field effect transistor and a versatile timing circuit all on one integrated circuit is provided. The integrated circuit has built in thermal and current limit protection and provides a fault indicator in case of an over current or an over temperature condition.

Integrated circuit power timer

A speed control circuit made by using CMOS processes is capable of handling high voltage and high current loads. The output of the speed control circuit is provided by a power field effect transistor. Current sensing means are provided to generate a fault signal in case an over current condition occurs. The junction temperature of the power field effect transistor is also monitored to provide an over temperature condition if the temperature of the junction of the power field effect transistor exceeds a predetermined value. A ramping generator is used to set a latch which controls the operation of the power field effect transistor. A speed control signal is compared against the ramping signal provided by the ramp generator and resets the latch in order to provide speed control.

Integrated circuit speed controller

Current sensing of current through an 'H' switch circuit is accomplished without the use of a dropping resistor. The current sensing is provided by using current sensing field effect transistors in conjunction with power field transistors.

MOSFET 'H' switch with current sensing

An MOS SCR and MOSFET 'H' switch circuit for a DC motor is provided which allows for the use of a supply voltage of greater than 20 volts by clamping the gate-to-cathode voltage of the SCR's used therein to a predetermined value which is less than the gate-to-cathode breakdown voltage of said SCR's.

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Chandler, AZ, United States of America

Jeffrey G Mansmann