Document
UC3717A
Stepper Motor Drive Circuit
FEATURES
• 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
DESCRIPTION
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 integrated 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 commutating 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.
ABSOLUTE MAXIMUM RATINGS (Note 1)
Voltage Logic Supply, VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V Output Supply, Vm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50V
Input Voltage Logic Inputs (Pins 7, 8, 9) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6V Analog Input (Pin 10). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . VCC 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 Junction Temperature, TJ. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C Storage Temperature Range, TS . . . . . . . . . . . . . . . . . . -55°C to +150°C
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 package.
Consult Packaging Section of Databook for thermal limitations and considerations of package.
BLOCK DIAGRAM
4/97 1
CONNECTION DIAGRAMS
DIL-16 (TOP VIEW) J or N Package
UC3717A
PLCC-20 (TOP VIEW) Q Package
PACKAGE PIN FUNCTION
FUNCTION
PIN
N/C 1
BOUT
2
Timing
3
Vm 4
Gnd 5
N/C 6
Gnd 7
VCC 8
I1 9
Phase
10
N/C 11
I0 12
Current
13
VR 14
Gnd 15
N/C 16
Gnd 17
Vm 18
AOUT
19
Emitters
20
ELECTRICAL CHARACTERISTICS (Refer to the test circuit, Figure 6. Vm = 36V, VCC = 5V, VR = 5V, TA = 0°C to 70°C,
unless otherwise stated, TA = TJ.)
PARAMETERS
TEST CONDITIONS
Supply Voltage, Vm (Pins 3, 14)
Logic Supply Voltage, VCC (Pin 6)
Logic Supply Current, ICC (Pin 6)
IO = I1 = 0
Thermal Shutdown Temperature
Logic Inputs
Input Low Voltage, (Pins 7, 8, 9)
Input High Voltage, (Pins 7, 8, 9)
Low Voltage Input Current, (Pins 7, 8, 9)
VI = 0.4V, Pin 8
VI = 0.4V, Pins 7 and 9
High Voltage Input Current, (Pins 7, 8, 9)
VI = 2.4V
Comparators
Comparator Low, Threshold Voltage (Pin 10) VR = 5V; IO = L; I1 = H
Comparator Medium, Threshold Voltage (Pin 10) VR = 5V; IO = H; I1 = L
Comparator High, Threshold Voltage (Pin 10) VR = 5V; IO = L; I1 = L
Comparator Input, Current (Pin 10)
Cutoff Time, tOFF
RT = 56kΩ, CT = 820pF
Turn Off Delay, tD
(See Figure 5)
Source Diode-Transistor Pair
Saturation Voltage, VSAT (Pins 1, 15)
Im = -0.5A, Conduction Period
(See Figure 5)
Im = -0.5A, Recirculation Period
Saturation Voltage, VSAT (Pins 1, 15)
Im = -1A,
Conduction Period
(See Figure 5)
Im = -1A,
Recirculation Period
Leakage Current
Vm = 40V
Diode Forward Voltage, VF
Im = -0.5A
Im = -1A
MIN TYP MAX UNITS
10 46 V
4.75 5.25 V
7 15 mA
+160
+180 °C
0.8 V
2
VCC
V
-100 µA
-400 mA
10 µA
66 80 90 mV 236 250 266 mV 396 420 436 mV
±20 µA 25 35 µs
2 µs
1.7 2.1 V 1.1 1.35 V 2.1 2.8 V 1.7 2.5 V
300 µA 1 1.25 V 1.3 1.7 V
2
UC3717A
ELECTRICAL
(Refer to the test circuit, Figure 6. VM = 36V, VCC = 5V, VR = 5V, TA = 0°C to 70°C, unless
CHARACTERISTICS (cont.) otherwise stated, TA = TJ.)
PARAMETERS
TEST CONDITIONS
MIN TYP MAX UNITS
Sink Diode-Transistor Pair
Saturation Voltage, VSAT (Pins 1, 15)
Im = 0.5A
0.8 1.1 1.35 V
Im = 1A
1.6 2.3 V
Leakage Current
Vm = 40V
300 µA
Diode Forward Voltage, VF
Im = 0.5A Im = 1A
1.1 1.5 1.4 2
V V
Figure 1. Typical Source Saturation Voltage vs Output Current (Recirculation Period)
Figure 2. Typical Source Saturation Voltage vs Output Current (Conduction Period)
Figure 3. Typical Sink Saturation Voltage vs Output Current
Figure 4. Typical P.