February 1999
PBL 3770A
High Performance
Stepper Motor Drive Circuit
Description
PBL 3770A is a bipolar monolithic circuit intended to control and drive the current in
one winding of a stepper motor. It is a high power version of PBL 3717 and special
care has been taken to optimize the power handling capability without suffering in
reliability.
The circuit consists of a LS-TTL compatible logic input stage, a current sensor, a
monostable multivibrator and a high power H-bridge output stage. The circuit is
pin-compatible with the PBL 3717 industry-standard driver.
Two PBL 3770A and a small number of external components form a complete
control and drive unit for LS-TTL or microprocessor-controlled stepper motor
systems.
Key Features
鈥?Half-step and full-step operation.
鈥?Switched mode bipolar constant
current drive
鈥?Wide range of current control
5 -1800 mA.
鈥?Wide voltage range 10 - 45 V.
鈥?Designed for unstabilized motor
supply voltage.
鈥?Current levels can be selected in
steps or varied continuously.
鈥?Thermal overload protection.
V
CC
Schmitt
Trigger
Time
Delay
V
MM
V
MM
Phase
I
1
1
鈮?
鈮?
P
L
B A
P 70
37
M
A
M
B
I
0
V
R
&
+
鈥?/div>
+
鈥?/div>
+
鈥?/div>
GND
&
&
&
鈮?
鈮?
B
Monostable
t
off
= 0.69 鈥?R
T
鈥?C
T
Current Sensor
L
PBL 3770A
C
T
E
37
7
16-pin plastic batwing DIP
28-pin plastic PLCC package
20-pin SO
Figure 1. Block diagram.
1
P
B
L
37
Output Stage
70
A
0A
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