UNITRODE UC1717, UC2717, UC3717 Technical data

The UC3717 has been designed to control and drive the current in
one winding of a bipolar stepper motor . The circuit consists of an LS­TTL-compatible logic input, a current senso r, a monostable and an
output stage with built-in protection diodes. Two UC3717s and a few
external components form a complete control and drive unit for LS­TTL or micro-proces sor contr o lled stepper motor system s.

The UC1717 is characterized for operation over the full military tem­perature range of -55°C to +125°C, the UC2717 is characterized for

-25°C to +85°C, and the UC3717 is characterized for 0°C to +70°C.

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Stepper Motor Drive Circuit

FEATURES DESCRIPTION

• Half-step and Full-step Capability

• Bipolar Constant Current Motor Drive

• Built-in Fast Recovery Schottky

Commutating Diodes

• Wide Range of Current Control 5-1000mA

• Wide Voltage Range 10-45V

• Designed for Unregulated Motor Supply

Voltage

• Current Levels can be Selected in Steps
or Varied Continuously

• Thermal Overload Protectio n

ABSOLUTE MAXIMUM RATINGS (Not e 1)

Voltage
Logic Supply, V
Output Supply, V
Input Voltage

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

Analog Input (Pin 10) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vcc

Reference I nput (Pin 11) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V

Input Current

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

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

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

Junction Temperature, T
Storage Temperature Range, T

CC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V

M . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45V

J. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150°C

S . . . . . . . . . . . . . . . . . . -55°C to +150°C

UC1717
UC2717
UC3717

Note 1: All voltages are with respect to ground, Pins
4,5, 12, 13. Pin num ber s refe r to DIL-16 packa ge. Cur­rents are positive int o, negat ive ou t of the spe cified ter­minal.
Note 2: Consult Packaging Sect ion of Databook for in­formation on thermal l imitat ions and considerations of
package.

BLOCK DIAGRAM

7/95

CONNECTION DIAG RAMS

Unless otherwise specified, these specifications apply for VCC = 5V, TA = TJ .

UC1717
UC2717
UC3717

DIL-16 (TOP VI EW)
J or N Package

RECOMMENDED OPERATING CONDITIONS

PARAMETER MIN TYP MAX UNITS

Supply Voltage, V
Supply Voltage, V
Output Current. I
Rise Time Logic Inputs, t
Fall Time Logic Inputs, t

Ambient Temperature, T

UC1717 -55 125 °C
UC2717 -25 85 °C
UC3717 0 70 °C

CC 4.75 5 5.25 V
M 10 40 V

M 20 800 mA

R 2 µs

F 2 µs

A

PLCC-20 (TOP VIEW)
Q Package

PACKAGE PIN FUNCTION

FUNCTION PIN

N/C
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

1

ELECTRICAL CHARACTERIST ICS

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Supply Curren t, I
High-Level Input Voltage, Pins 7, 8, 9 2.0 V
Low-Level I nput Voltage, Pins 7, 8, 9 0.8 V
High-Level Input Current , Pins 7, 8, 9 V
Low Level Input Curre nt, Pins 7, 8, 9 V
Compara tor Thresh old Volta ge I

Compara to r Input Cur ren t -20 20 µA
Output Leakage Current I
Total Saturation Voltage Drop I
Total Power Dissipation I

Cut Off Time, t
Turn Off Delay, t
Thermal Shutd own Jun ctio n Tem per atur e +160 +180 ° C

CC 25 mA

I = 2.4V 20 µA
I = 0.4V -0.4 mA

O = 0, I1 = 0, VR = 5.0V 390 420 440 mV

I

O = 1, I1 = 0, VR = 5.0V 230 250 270 mV

I

O = 0, I1 = 1, VR = 5.0V 65 80 90 mV

O = 1, I1 = 1, TA = +25°C 100 µA
M = 500mA 4.0 V
M = 500mA, fS = 30kHz 1.4 2.1 W

I

M = 800mA, fS = 30kHz 2.9 3.1 W

OFF VM = 10 V, tON≥ 5µs (See Figure 5 and 6) 25 30 35 µs

D TA = +25°C; dVc/dt ≥ 50mV/µs (See Figure 5 and 6) 1.6 2 .0 µs

2

UC1717
UC2717
UC3717

Figure 1

Figure 2: Ty pical Sour ce Satur at ion Voltage vs Outp ut Curr ent

FUNCTIONAL DESCRI PT IO N

The UC3717 drive circuit shown in the block diagram in­cludes the following functions:

(1) Phase Logic and H-Bridge Output Stage
(2) V o ltag e D i v id er w i t h t h r e e C o m p a r a t ors f o r cur r e n t cont r o l
(3) Tw o Logic inputs for Digit al current lev el selec t
(4) Monostable for off time ge nerat ion

Figure 3: Ty pical Sink Sat ura tion Voltage vs Outpu t Cur rent

Figure 4: Typical Power Losse s vs Output Cur ren t

Input Logic: If any of the logic inputs are left open, the

circuit will treat it as a high level input.
Phase Input: The phase input terminal, pin 18, controls

the direction of the current through the motor winding.
The Schmidt-Trigger input coupled with a fixed time de­lay assures noise immunity and eliminates cross conduc­tion in the output stage during phase changes. A low
level on the phase input will turn Q2 on and enable Q3
while a high level wi ll turn Q1 on and enable Q4. (See
Figure 7).

Output Stage: The output stage consists of four Dar­lington transistors and associated diodes connected in
an H-Bridge configuration. The diodes are needed to pro­vide a current path when the transistors are being
switched. For fast recovery, Schottky diodes are used

Figure 5: Connections and Compone nt Values as in Figure 6.

across the source transistors. The Schottky diodes allow
the current to circulate through the winding while the sink
transistors are being switched off. The diodes across the
sink transistors in conjuncti on with the Schottkys provide
the path for the decaying current during phase reversal.
(See Figure 7).

PHASE INPUT Q1, Q4 Q2, Q3

Low Off On

High On Off

3