4/97

•

Full-Step, Half-Step and Micro-Step

Capability

•

Bipolar Output Current up to 1A

•

Wide Range of Motor Supply Voltage

10-46V

•

Low Saturation Voltage with Integrated

Bootstrap

•

Built-In Fast Recovery Commutating

Diodes

•

Current Levels Selected in Steps or Varied

Continuously

•

Thermal Protection with Soft Intervention

Stepper Motor Drive Circuit

The UC3717A is an improved version of the UC3717, used to switch

drive the current in one winding of a bipolar stepper motor.

The

UC3717A has been modified to supply higher winding current, more

reliable thermal protection, and improved efficiency by providing inte-

grated bootstrap circuitry to lower recirculation saturation voltages.

The diagram shown below presents the building blocks of the

UC3717A. Included are an LS-TTL compatible logic input, a current

sensor, a monostable, a thermal shutdown network, and an H-bridge

output stage. The output stage features built-in fast recovery com-

mutating diodes and integrated bootstrap pull up. Two UC3717As

and a few external components form a complete control and drive

unit for LS-TTL or micro-processor controlled stepper motor systems.

The UC3717A is characterized for operation over the temperature

range of 0°C to +70°C.

UC3717A

BLOCK DIAGRAM

FEATURES

DESCRIPTION

Voltage

Input Voltage

Logic Inputs (Pins 7, 8, 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V

Reference Input (Pin 11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V

Input Current

Logic Inputs (Pins 7, 8, 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10mA

Analog Inputs (Pins 10, 11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10mA

Output Current (Pins 1, 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

±1.2A

ABSOLUTE MAXIMUM RATINGS (Note 1)

Note 1: All voltages are with respect to ground, Pins 4,

5, 12, 13. Currents are positive into, negative out of the

specified terminal. Pin numbers refer to DIL-16 pack-

age.

Consult Packaging Section of Databook for thermal limi-

tations and considerations of package.

1