February 1999
28-pin PLCC package
22-pin plastic DIP package
24-pin SO package
Key Features
Dual chopper driver in a single
package.
Operation down to -40
C.
750 mA continuous output current
per channel.
Low power dissipation, 2.0 W at
2 x 500 mA output current.
Close matching between channels
for high microstepping accuracy.
Digital filter on chip eliminates
external filtering components.
Plastic 22-pin batwing DIL package,
24-pin SOIC batwing or 28-pin power
PLCC. All with lead-frame for
heatsinking through PC board
copper.
PBL 3775/1
Dual Stepper Motor Driver
Description
The PBL 3775/1 is a switch-mode (chopper), constant-current driver IC with two
channels, one for each winding of a two-phase stepper motor. The circuit is similar to
Ericssons PBL 3773/1. While several of Ericssons dual stepper motor drivers are
optimized for micro-stepping applications, PBL 3775/1 is equipped with a disable
input to simplify half-stepping operation.
The PBL 3775/1 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, including recirculation diodes.
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.
PBL3775/1
PBL
3775/1
RC
PBL 3775/1
M
A1
M
B1
M
B2
M
A2
GND
C
2
V
R2
Phase
2
V
CC
C
1
V
R1
Phase
1
E
1
E
2
V
CC
S
R
Q
Logic
S
R
Q
+
Logic
+
V
MM2
V
MM1
Dis
1
Dis
2
+
Figure 1. Block diagram
PBL 3775/1
PBL 3775/1
2
Maximum Ratings
Parameter
Pin No. (DIP)
Symbol
Min
Max
Unit
Voltage
Logic supply
12
V
CC
0
7
V
Motor supply
4, 19
V
MM
0
45
V
Logic inputs
9, 10, 13, 14
V
I
-0.3
6
V
Analog inputs
7, 8, 15, 16
V
A
-0.3
V
CC
V
Current
Motor output current
1, 3, 20, 22
I
M
-850
+850
mA
Logic inputs
9, 10, 13, 14
I
I
-10
mA
Analog inputs
7, 8, 15, 16
I
A
-10
mA
Temperature
Operating junction temperature
T
J
-40
+150
C
Storage temperature
T
S
-55
+150
C
Power Dissipation (Package Data)
Power dissipation at T
BW
= +25
C, DIP and PLCC package
P
D
5
W
Power dissipation at T
BW
= +125
C, DIP package
P
D
2.2
W
Power dissipation at T
BW
= +125
C, PLCC package
P
D
2.6
W
Recommended Operating Conditions
Parameter
Symbol
Min
Typ
Max
Unit
Logic supply voltage
V
CC
4.75
5
5.25
V
Motor supply voltage
V
MM
10
40
V
Output emitter voltage
V
E
1.0
V
Motor output current
I
M
-750
+750
mA
Operating junction temperature
T
J
-20
+125
C
Rise and fall time logic inputs
t
r,
, t
f
2
s
Oscillator timing resistor
R
T
2
12
20
kohm
Figure 3. Definition of terms.
Figure 2. Definition of symbols.
V
R
t
d
t
50 %
t
on
t
off
| V V |
MA
MB
t
t
V
RC
t
b
V ( I )
E
M
f =
s
ton toff
+
1
D =
t
t
on
off
+
t
on
I I
M OL
ICC
I I I
I IH IL
IA
4 700 pF
VCC
V
V
V
I
IH
IL
V
V
A
R
V
V
V
CH
C
A
I
I
C
A
V E
VMM
R
S
R T
12 kW
I MM
C
T
IR
V
RC
IRC
V MA
VM
RC
PBL 3775/1
19
11
12
M
A1
M
B1
M
B2
M A2
GND
C2
V
R2
Phase 2
V
CC
C
1
V
R1
Phase
1
E 1
E 2
V
CC
22
20
14
15
S
R
Q
16
5, 6, 17, 18
Logic
21
S
R
Q
+
Logic
+
4
1
3
2
8
7
9
VMM2
VMM1
Dis
1
10
Dis
13
2
+
PBL 3775/1
3
Electrical Characteristics
Electrical characteristics over recommended operating conditions, unless otherwise noted. - 20
C
T
j
+ 125
C.
Ref.
Parameter
Symbol fig.
Conditions
Min
Typ
Max
Unit
General
Supply current
I
CC
2
Note 4.
55
70
mA
Supply current
I
CC
2
Dis
1
= Dis
2
= HIGH.
7
10
mA
Total power dissipation
P
D
8
V
MM
= 24 V, I
M1
= I
M2
= 500 mA.
2.0
2.3
W
Notes 2, 3, 4.
Total power dissipation
P
D
8
V
MM
= 24 V, I
M1
= 700 mA, I
M2
= 0 mA.
1.7
2.0
W
Notes 2, 3, 4.
Thermal shutdown junction temperature
160
C
Turn-off delay
t
d
3
T
A
= +25
C, dV
C
/dt
50 mV/
s,
1.1
2.0
s
I
M
= 100 mA. Note 3.
Logic Inputs
Logic HIGH input voltage
V
IH
2
2.0
V
Logic LOW input voltage
V
IL
2
0.6
V
Logic HIGH input current
I
IH
2
V
I
= 2.4 V
20
A
Logic LOW input current
I
IL
2
V
I
= 0.4 V
-0.2
-0.1
mA
Analog Inputs
Threshold voltage
V
CH
2
V
R
=5 V
480
500
520
mV
Input current
I
A
2
V
R
= 5 V
500
A
|V
C1
--V
C2
| mismatch
V
Cdiff
2
1
mV
Motor Outputs
Lower transistor saturation voltage
10
I
M
= 500 mA
0.4
0.8
V
Lower transistor leakage current
2
V
MM
=41 V,T
A
= +25
C. Dis
1
= Dis
2
= HIGH.
100
A
Lower diode forward voltage drop
11
I
M
= 500 mA
1.1
1.3
V
Upper transistor saturation voltage
12
I
M
= 500 mA.
1.1
1.4
V
Upper diode forward voltage drop
13
I
M
= 500 mA.
1.1
1.4
V
Upper transistor leakage current
2
V
MM
=41 V,T
A
= +25
C. Dis
1
= Dis
2
= HIGH.
.
100
A
Chopper Oscillator
Chopping frequency
f
s
3
C
T
= 4 700 pF, R
T
= 12 kohm
21.5
23.0
24.5
kHz
Digital filter blanking time
t
b
3
C
T
= 4 700 pF. Note 3.
1.0
s
Thermal Characteristics
Ref.
Parameter
Symbol fig.
Conditions
Min
Typ
Max
Unit
Thermal resistance
Rth
J-BW
DIL package.
11
C/W
Rth
J-A
14
DIL package. Note 2.
40
C/W
Rth
J-BW
PLCC package.
9
C/W
Rth
J-A
14
PLCC package. Note 2.
35
C/W
Rth
j-c
SO package
13
C/W
Rth
j-a
SO package
42
C/W
Notes
1. All voltages are with respect to ground. Currents are positive into, negative out of specified terminal.
2. All ground pins soldered onto a 20 cm
2
PCB copper area with free air convection, T
A
= + 25
C.
3. Not covered by final test program.
4. Switching duty cycle D = 30 %, f
s
= 23.0 kHz.
PBL 3775/1
4
Pin Description
SO
DIP
PLCC
Symbol
Description
2
1
[8]
M
B1
Motor output B, channel 1. Motor current flows from M
A1
to M
B1
when Phase
1
is HIGH.
3
2
[10]
E
1
Common emitter, channel 1. This pin connects to a sensing resistor R
S
to ground.
4
3
[11]
M
A1
Motor output A, channel 1. Motor current flows from M
A1
to M
B1
when Phase
1
is HIGH.
5
4
[12]
V
MM1
Motor supply voltage, channel 1, +10 to +40 V. V
MM1
and V
MM2
should be connected together.
6,7
5, 6,
[1-3, 9,
GND
Ground and negative supply. Note: these pins are used thermally for heat-sinking.
18,19 17, 18 13-17,
Make sure that all ground pins are soldered onto a suitably large copper ground plane
28]
for efficient heat sinking.
8
7
[18]
V
R1
Reference voltage, channel 1. Controls the comparator threshold voltage and hence the output
current.
9
8
[19]
C
1
Comparator input channel 1. This input senses the instantaneous voltage across the sensing
resistor, filtered by the internal digital filter or an optional external RC network.
10
9
[20]
Phase
1
Controls the direction of motor current at outputs M
A1
and M
B1
. Motor current
flows from M
A1
to M
B1
when Phase
1
is HIGH.
11
10
[21]
Dis
1
Disable input for channel 1. When HIGH, all four output transistors are turned off, which results
in a rapidly decreasing output current to zero.
12
11
[22]
RC
Clock oscillator RC pin. Connect a 12 kohm resistor to V
CC
and a 4 700 pF capacitor to ground
to obtain the nominal switching frequency of 23.0 kHz and a digital filter blanking time of 1.0
s.
13
12
[23]
V
CC
Logic voltage supply, nominally +5 V.
14
13
[24]
Dis
2
Disable input for channel 2. When HIGH, all four output transistors are turned off, which results
in a rapidly decreasing output current to zero.
15
14
[25]
Phase
2
Controls the direction of motor current at outputs M
A2
and M
B2
. Motor current
flows from M
A2
to M
B2
when Phase
2
is HIGH.
16
15
[26]
C
2
Comparator input channel 2. This input senses the instantaneous voltage across the sensing
resistor, filtered by the internal digital filter or an optional external RC network.
17
16
[27]
V
R2
Reference voltage, channel 2. Controls the comparator threshold voltage and hence the output
current.
20
19
[4]
V
MM2
Motor supply voltage, channel 2, +10 to +40 V. V
MM1
and V
MM2
should be connected together.
21
20
[5]
M
A2
Motor output A, channel 2. Motor current flows from M
A2
to M
B2
when Phase
2
is HIGH.
22
21
[6]
E
2
Common emitter, channel 2. This pin connects to a sensing resistor R
S
to ground.
23
22
[7]
M
B2
Motor output B, channel 2. Motor current flows from M
A2
to M
B2
when Phase
2
is HIGH.
1,24
NC
SO pin 1 & 24 is "Not Connected"
Figure 4. Pin configuration.
E
B2
B1
GND
RC
GND
GND
GND
GND
GND
GND
GND
GND
GND
5
6
7
8
9
10
11
25
24
23
22
21
20
19
4
3
2
1
28
27
26
12
13
14
15
16
17
18
V
R2
V
R1
V
CC
Phase
2
M
A2
2
Dis
M
M
1
Dis
A1
M
1
Phase
C
2
C
1
2
V
MM1
E
1
V
MM2
PBL 3775/1QN
1
2
3
4
5
6
7
8
9
10
11
22
21
20
19
18
17
16
15
14
13
12
C
R2
A1
GND
GND
1
R1
CC
M
V
M
GND
GND
Phase
Dis
RC
V
M
Phase
V
V
2
2
A2
MM2
B2
2
E
2
C
1
Dis
1
V
MM1
M
B1
E
1
PBL
3775/1N
1
2
3
4
5
6
8
9
10
11
22
21
20
19
18
17
16
15
14
13
12
GND
MA
1
Dis
1
MA
2
GND
NC
Phase
1
PBL
3775/1SO
MB
1
E
1
VMM
1
NC
MB
2
E
2
VMM
2
VR
1
VR
2
C
2
C
1
Dis
2
V
cc
RC
23
24
GND
GND
Phase
2
7
PBL 3775/1
5
Figure 6. Typical stepper motor driver application with PBL 3775/1.
Figure 5. Output stage with current paths
during turn-on, turn-off and phase shift.
Functional Description
Each channel of the PBL 3775/1
consists of the following sections: an
output H-bridge with four transistors and
four recirculation diodes, capable of
driving up to 750 mA continuous current
to the motor winding,
a logic section that controls the output
transistors, an S-R flip-flop, and a com-
parator. The clock-oscillator is common
to both channels.
Constant current control is achieved
by switching the output current to the
windings. This is done by sensing the
peak current through the winding via a
current-sensing resistor R
S
, effectively
connected in series with the motor
winding. As the current increases, a
voltage develops across the sensing
resistor, which is fed back to the
comparator. At the predetermined level,
defined by the voltage at the reference
input V
R
, the comparator resets the flip-
flop, which turns off the upper output
transistor. The turn-off of one channel is
independent of the other channel. The
current decreases until the clock
oscillator triggers the flip-flops of both
channels simultaneously, which turns on
the output transistors again, and the
cycle is repeated.
To prevent erroneous switching due to
switching transients at turn-on, the
PBL 3775/1 includes a digital filter. The
clock oscillator provides a blanking
pulse which is used for digital filtering of
the voltage transient across the current
sensing resistor during turn-on.
The current paths during turn-on, turn-
off and phase shift are shown in figure 5.
Applications Information
Current control
The regulated output current level to the
motor winding is determined by the
voltage at the reference input and the
value of the sensing resistor, R
S
. The
peak current through the sensing
resistor (and the motor winding) can be
expressed as:
I
M,peak
= 0.1V
R
/ R
S
[A]
With a recommended value of 0.5 ohm
for the sensing resistor R
S
, a 2.5 V
reference voltage will produce an output
current of approximately 500 mA. R
S
should be selected for maximum motor
current. Be sure not to exceed the
absolute maximum output current which
is 850 mA. Chopping frequency, winding
inductance and supply voltage also
affect the current, but to much less
extent.
For accurate current regulation, the
sensing resistor should be a 0.5 - 1.0 W
precision resistor, i. e. less than 1%
tolerance and low temperature
coefficient.
Current sense filtering
At turn-on a current spike occurs, due to
the recovery of the recirculation diodes
and the capacitance of the motor
winding. To prevent this spike from
reseting the flip-flops through the
current sensing comparators, the clock
oscillator generates a blanking pulse at
turn-on. The blanking pulse pulse
disables the comparators for a short
time. Thereby any voltage transient
across the sensing resistor will be
ignored during the blanking time.
3
2
1
R
S
V
MM
Fast Current Decay
Slow Current Decay
Motor Current
Time
1 2
3
Phase
Dis
V
Phase
Dis
V
1
1
2
2
R1
R2
E
C
E
C
GND
RC
PBL 3775/1
12 k
4 700 pF
0.47
0.47
M
M
M
M
A1
B1
A2
B2
V
CC
V
V
MM1
MM2
+5 V
+5 V
3
1
20
22
9
10
7
12
4
19
11
5, 6,
17, 18
2
15
21
8
1
1
2
2
R S
R S
14
13
16
STEPPER
MOTOR
V
MM
Pin numbers refer
to DIL package.
+
10
F
0.1
F
GND (V )
GND (V
)
0.1
F
MM
CC
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