Abstract: A ring counter includes a plurality of latches forming a shift register. A single bit is sequentially clocked through the shift register, so that only one output is active at any time. A logic circuit is connected to the outputs, and monitors the number of outputs which are active. If more than one output should somehow become active at one time, such as during power up, a reset signal is immediately generated to reset a single bit of the counter active. An external reset signal can also be applied to the logic circuit to force a reset of the counter.

Abstract: A capacitive load driver is protected from short circuits to supply or to ground. The load driver includes an edge detecting monostable circuit and a plurality of sets of field effect transistor (FET) output devices, one set of the FET output devices having a low drain-to-source resistance and another set having a high drain-to-source resistance. The low resistance FET output devices provide a desired rise time voltage requirement on a capacitive load being driven. The high resistance FET output devices limit power dissipated under a short circuit to a predetermined amount.

Abstract: An improved gate drive circuit for a MOS power transistor utilizes a dual gate drive circuit configuration. The first gate drive circuit operates to quickly turn on the MOS power transistor. After the MOS power transistor is turned on, the first gate drive circuit can be disabled. A second gate drive circuit is employed to provide continuous drive to the gate of the MOS power transistor to keep the MOS power transistor on.

Abstract: A motor controller provides a digital monostable circuit which generates a control signal indicating whether a field coil within a motor should be turned on or off. Two registers are provided within the digital monostable to store values indicating a fixed off time and a minimum on time. These registers can be loaded with selected values by a microprocessor or other controller. The stored values are selectively loaded into a counter which, when the field coil current reaches a preselected level, turns the supply to the field coil off for a time corresponding to the off time value, then on again for a period at least as long as the minimum on time value. The values in the off time and minimum on time registers can be changed to suit operating conditions of the system, and the controller can be operated in either PWM or open loop mode.