The L297 stepper motor controller IC generates four phase drive signals for two phase bipolar and four phase unipolar step motors in microcomputer controlled applications. The motor can be driven in half step, normal and wave drive modes, and on-chip PWM chopper circuits permit switch-mode control of the current in the windings. A feature of this device is that it requires only clock, direction and mode input signals. Since the phase is generated internally, the burden on the microprocessor and the programmer is greatly reduced. Mounted in DIP20, the L297 can be used with monolithic bridge drives such as the L298N or L293E, or with discrete transistors and darlingtons.