February 1999
PBL 3774/1
Dual Stepper Motor Driver
Description
The PBL 3774/1 is a switch-mode (chopper), constant-current driver IC with two chan-
nels, one for each winding of a two-phase stepper motor. The circuit is similar to
Ericsson´s PBL 3771/1 and PBL 3772/1. While all Dual stepper motor drivers are
optimized for microstepping applications, the PBL 3774/1 is equipped with a TTL level
compatible Disable input to simplify half-stepping operation.
The circuit is well suited for microstepping applications together with the matching
dual DAC (Digital-to-Analog Converter) PBM 3960/1. A complete driver system
consists of these two ICs, a few passive components and a microprocessor for
generation of the proper control and data codes required for microstepping.
In full/halfstepping applications, Ericsson Component’s PBD 3517/1 can be used as
a phase generator (translator) to derive the necessary signals for the PBL 3774/1.
The PBL 3774/1 contains a clock oscillator, which is common for both driver
channels, a set of comparators and flip-flops implementing the switching control, and
two output H-bridges.
Voltage supply requirements are +5 V for logic and +10 to +45 V for the motor.
The close match between the two driver channels guarantees consistent output
current ratios and motor positioning accuracy.
Key Features
• Dual chopper driver in a single
package.
• Operation at -40
°C.
• 1000 mA continuous output current
per channel.
• Low power dissipation, 2.6 W at
2 x 750 mA output current.
• Close matching between channels for
high microstepping accuracy.
• Specially matched to the Dual DAC
PBM 3960.
• Plastic 22-pin batwing DIP package
or 28-pin power PLCC package with
lead-frame for heatsinking through
PC board copper.
Phase
1
Dis
1
V
R1
C
1
E
1
PBL 3774/1
V
CC
V
–
+
CC
L
B /1
P 74
37
R
S
Q
M
A1
Logic
–
M
B2
Logic
RC
+
–
M
A2
S
R
Q
Phase
2
Dis
2
V
R2
C
2
GND
E
2
28-pin PLCC package
22-pin plastic DIL package
Figure 1. Block diagram.
1
P
B
L
+
V
MM2
37
V
MM1
74
/1
M
B1
ERICSSON [ ERICSSON ]
