The 33977 is a Serial Peripheral Interface (SPI) Controlled, stepper motor gauge driver Integrated Circuit (IC). This monolithic IC consists of a dual H-Bridge coil driver and its associated control logic. The HBridge drivers are used to automatically control the speed, direction, and magnitude of current through the coils of a two-phase instrumentation stepper motor, similar to an MMT-licensed AFIC 6405 of Switec MS-X156.xxx motor.