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 U C3717A is a n impro ved v ersio n 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
UC3 717A. Included are an LS-TTL compatible l ogic input, a current
sens or, a monos tabl e, a th ermal shu tdow n netw ork , and an H-bri dge
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
Logic Supply, V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V
Output Supply, V
m
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50V
Input Vol ta ge
Logic Inputs (Pins 7, 8, 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V
Analog Input (Pin 10). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V
CC
Reference Input (Pin 11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V
Input Curre nt
Logic Inputs (Pins 7, 8, 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10mA
Analog Inputs (Pins 10, 11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . -10mA
Output Current (Pins 1, 15) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
±
1.2A
Junction Temperature, T
J
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C
Storage Temperature Range, T
S
. . . . . . . . . . . . . . . . . . -55°C to +150°C
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
