Integrated Circuit


Combining low-power CMOS logic with high-current and high-voltage bipolar outputs, the UCN5804B and UCN5804LB BiMOS II translator/ drivers provide complete control and drive for a four-phase unipolar stepper- motor with continuous output current ratings to 1.25 A per phase (1.5 A startup) and 35 V.

The CMOS logic section provides the sequencing logic, DIRECTION and OUTPUT ENABLE control, and a power-on reset function. Three stepper-motor drive formats, wave-drive (one-phase), two-phase, and half- step are externally selectable. The inputs are compatible with standard CMOS, PMOS, and NMOS circuits. TTL or LSTTL may require the use of appropriate pull-up resistors to ensure a proper input-logic high.

The wave-drive format consists of energizing one motor phase at a time in an A-B-C-D (or D-C-B-A) sequence. This excitation mode consumes the least power and assures positional accuracy regardless of any winding inbalance in the motor. Two-phase drive energizes two adjacent phases in each detent position (AB-BC-CD-DA). This sequence mode offers an improved torque-speed product, greater detent torque, and is less susceptible to motor resonance. Half-step excitation alternates between the one-phase and two-phase modes (A-AB-B-BC-C-CD-D-DA), providing an eight-step sequence.

The bipolar outputs are capable of sinking up to 1.5 A and withstanding 50 V in the off state (sustaining voltages up to 35 V). Ground-clamp and flyback diodes provide protection against inductive transients. Thermal protection circuitry disables the outputs when the chip temperature is exces- sive.

Both devices are rated for operation over the temperature range of -20°C to +85°C. The UCN5804B is supplied in a 16-pin dual in-line plastic batwing package with a copper lead frame and heat-sinkable tabs for improved power dissipation capabilities; the UCN5804LB is supplied in a 16-lead plastic SOIC batwing package with a copper lead frame and heat-sinkable tabs.