3964, katalog

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3964
DUAL FULL-BRIDGE PWM MOTOR DRIVER
A3964SLB
Designed for pulse-width modulated (PWM) current control of bipolar
stepper motors, the A3964SB and A3964SLB are capable of continuous
output currents to
800 mA and operating voltages to 30 V. Internal fixed
off-time PWM current-control circuitry can be used to regulate the maximum
load current to a desired value. An internal precision voltage reference is
provided to improve motor peak-current control accuracy. The peak load
current limit is set by the user’s selection of an external resistor divider and
current-sensing resistors.
±
OUT
1B
1
20
OUT
2B
SENSE
1
2
1
2
19
SENSE
2
OUT
1A
3
18
OUT
2A
V
BB
LOAD
SUPPLY
LOGIC
SUPPLY
4
V
CC
17
The fixed off-time pulse duration is set by user-selected external RC
timing networks. The capacitor in the RC timing network also determines a
user-selectable blanking window that prevents false triggering of the PWM
current control circuitry during switching transitions. This eliminates the
need for two external RC filter networks on the current-sensing comparator
inputs.
GROUND
5
16
GROUND
GROUND
6
15
GROUND
V
REF(IN)
7
14
V
REF(OUT)
RC
1
8
9
13
RC
2
PHASE
1
9
θ
1
θ
2
12
PHASE
2
For each bridge the PHASE input controls load current polarity by
selecting the appropriate source and sink driver pair. For each bridge the
ENABLE input, when held high, disables the output drivers. Special power-
up sequencing is not required. Internal circuit protection includes thermal
shutdown with hysteresis, transient-suppression diodes, and crossover-current
protection.
ENABLE
1
10
11
ENABLE
2
Dwg. PP-047-1
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, V
BB
. . . . . . . . .
33 V
Output Current, I
OUT
(10
µ
s) . . . . . .
±
1.0 A*
The A3964SB is supplied in a 24-pin plastic DIP with copper heat sink
tabs; A3964SLB is supplied in a 20-lead plastic SOIC with copper heat sink
tabs. The power tabs are at ground potential and need no electrical isolation.
800 mA*
Logic Supply Voltage, V
CC
. . . . . . . . .
7.0 V
Logic Input Voltage Range,
V
IN
. . . . . . . . . . .
-0.3 V to V
CC
+ 0.3 V
Sense Voltage, V
S
. . . . . . . . . . . . . . .
1.0 V
Reference Output Current,
I
REF(OUT)
. . . . . . . . . . . . . . . . . .
1.0 mA
Package Power Dissipation,
P
D
. . . . . . . . . . . . . . . . . . . .
See Graph
Operating Temperature Range,
T
A
. . . . . . . . . . . . . . . .
-20˚C to +85˚C
Junction Temperature, T
J
. . . . . . .
+150˚C†
Storage Temperature Range,
T
S
. . . . . . . . . . . . . . .
-55˚C to +150˚C
* Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any set
of conditions, do not exceed the specified current rating
or a junction temperature of 150˚C.
† Fault conditions that produce excessive junction
temperature will activate the device’s thermal shutdown
circuitry. These conditions can be tolerated but should
be avoided.
±
800 mA Continuous Output Current Rating
30 V Output Voltage Rating
Internal PWM Current Control, Saturated Sink Drivers
Internally Generated, Precision 2.5 V Reference
Internal Transient-Suppression Diodes
Internal Thermal-Shutdown Circuitry
Crossover-Current Protection, UVLO Protection
Always order by complete part number:
Part Number
Package
A3964SB
24-Pin DIP
A3964SLB
20-Lead Wide-Body SOIC
(continuous) . . . . . . . . . . . . .
FEATURES
±
3964
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
A3964SB
5
NO
CONNECT.
1
NC
NC
24
NO
CONNECT.
R = 6.0
°
C/W
θ
JT
OUT
1B
2
23
OUT
2B
4
SENSE
1
3
1
2
22
SENSE
2
OUT
1A
4
21
OUT
2A
3
LOAD
SUPPLY
5
V
BB
V
CC
20
LOGIC
SUPPLY
SUFFIX 'B', R = 40
θ
JA
°
C/W
GROUND
6
19
GROUND
2
GROUND
7
18
GROUND
V
REF(IN)
8
17
V
REF(OUT)
1
RC
1
9
9
16
RC
2
SUFFIX 'LB', R = 60
θ
JA
°
C/W
PHASE
1
10
θ
1
θ
2
15
PHASE
2
0
ENABLE
1
11
14
ENABLE
2
25
50
75
100
125
150
NO
CONNECT.
NO
CONNECT.
TEMPERATURE IN
°
C
12
NC
NC
13
Dwg. GP-049-4
Dwg. PP-005-2
FUNCTIONAL BLOCK DIAGRAM
(A3964SLB pinning shown)
17
3
1
4
18
20
UVLO
& TSD
V
CC
V
BB
PHASE
1
9
12
PHASE
2
1
2
ENABLE
1
10
11
ENABLE
2
SOURCE
DIS
A
BLE
2.5 V
REFERENCE
SOURCE
DIS
A
BLE
V
REF(IN)
–
+
–
+
ONE SHOT
ONE SHOT
8
2
14
7
5
6
1
516
19
13
R
T
R
A
R
B
R
S
R
T
C
T
R
S
C
T
Dwg. FP-033-1
2
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
Copyright © 1997, 2000 Allegro MicroSystems, Inc.
3964
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
TRUTH TABLE
ENABLE
PHASE
OUT
A
OUT
B
H
X
Off
Off
L
H
H
L
L
L
L
H
X = Irrelevant
ELECTRICAL CHARACTERISTICS at T
A
= +25
°
C, V
BB
= 30 V, V
CC
= 4.75 V to 5.25 V,
V
S
= 0 V, 30 k
Ω
& 1000 pF RC to Ground (unless noted otherwise)
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Output Drivers
Load Supply Voltage Range
V
BB
Operating, I
OUT
=
±
800 mA, L = 3 mH
5.0 — 30
V
Output Sustaining Voltage
V
CE(sus)
I
OUT
=
±
800 mA, L = 3 mH, V
BB
= 33 V
33 ——V
Output Leakage Current
I
CEX
V
OUT
= V
BB
= 33 V
— <1.0
50
µ
A
V
OUT
= 0 V, V
BB
= 33 V
— <1.0
-50
µ
A
Output Saturation Voltage
V
CE(SAT)
Source Driver, I
OUT
= -500 mA
— 1.0
1.2
V
Source Driver, I
OUT
= -750 mA
— 1.1
1.5
V
Source Driver, I
OUT
= -800 mA ——1.7
V
Sink Driver, I
OUT
= +500 mA
— 0.3
0.6
V
Sink Driver, I
OUT
= +750 mA
— 0.5
1.2
V
Sink Driver, I
OUT
= +800 mA ——1.5
V
Clamp Diode Forward Voltage
V
F
I
F
= 500 mA
— 1.1
1.4
V
(Sink or Source)
I
F
= 750 mA
— 1.3
1.6
V
I
F
= 800 mA ——1.7
V
Motor Supply Current
I
BB(ON)
V
ENABLE
= 0.8 V
— 2.0
4.0
mA
(No Load)
I
BB(OFF)
V
ENABLE
= 2.4 V
— 0
500
µ
A
NOTES: 1. Typical Data is for design information only.
2. Negative current is defined as coming out of (sourcing) the specified device terminal.
www.allegromicro.com
3
3964
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at T
A
= +25
Ω
& 1000 pF RC to Ground (unless noted otherwise) (cont.)
°
C, V
BB
= 30 V, V
CC
= 4.75 V to 5.25 V,
Limits
Characteristic
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Control Logic
Logic Supply Voltage Range
V
CC
Operating
4.75 — 5.25
V
Logic Input Voltage
V
IN(1)
2.4 ——V
V
IN(0)
——0.8
V
Logic Input Current
I
IN(1)
V
IN
= 2.4 V
— <1.0
20
µ
A
I
IN(0)
V
IN
= 0.8 V
— <-2.0
-200
µ
A
Reference Output Voltage
V
REF(OUT)
V
CC
= 5.0 V, I
REF(OUT)
= 90 to 900
µ
A
2.45
2.50
2.55
V
Reference Output Current
I
REF(OUT)
3 k
Ω
≤
R
D
= R
A
+ R
B
≤
15 k
Ω
150 — 900
µ
A
Ref. Input Offset Current
I
OS
V
REF(IN)
= 1 V
-2.5
0
1.0
µ
A
Comparator Input Offset Volt.
V
IO
V
REF(IN)
= 0 V
-6.0
0
6.0
mV
Comparator Input Volt. Range
V
REF
Operating
-0.3 — 1.0
V
PWM RC Fixed Off-time
t
OFF RC
C
T
= 1000 pF, R
T
= 30 k
Ω
27
30
33
µ
s
PWM Propagation Delay Time
t
PWM
Comparator Trip to Source Off
— 1.2
2.0
µ
s
PWM Minimum On Time
t
ON(min)
C
T
= 1000 pF, R
T
≥
15 k
Ω
, V
CC
= 5 V — 2.5
3.6
µ
s
Propagation Delay Times
t
pd
800 mA, 50% to 90%:
ENABLE On to Source On
±
— 3.2 —
µ
s
ENABLE Off to Source Off
— 1.2 —
µ
s
ENABLE On to Sink On
— 3.2 —
µ
s
ENABLE Off to Sink Off
— 0.7 —
µ
s
PHASE Change to Sink On
— 3.2 —
µ
s
PHASE Change to Source On
— 3.2 —
µ
s
PHASE Change to Sink Off
— 0.7 —
µ
s
PHASE Change to Source Off
— 1.2 —
µ
s
Thermal Shutdown Temp.
T
J
— 165 —
°
C
Thermal Shutdown Hysteresis
∆
T
J
— 15 —
°
C
UVLO Disable Threshold
Decreasing V
CC
4.20
4.40
4.65
V
UVLO Hysteresis
UVLO Enable Volt. - UVLO Disable Volt. 0.075
0.125
0.175
V
UVLO Enable Threshold
Increasing V
CC
4.375
4.525
4.725
V
Logic Supply Current
I
CC(ON)
V
ENABLE 1
= V
ENABLE 2
= 0.8 V
— 60
85
mA
I
CC(OFF)
V
ENABLE 1
= V
ENABLE 2
= 2.4 V
— 13
17
mA
Logic Supply Current
∆
I
CC(ON)
V
ENABLE 1
=
V
ENABLE 2
= 0.8 V
— 0.18 — mA/
°
C
Temperature Coefficient
NOTES: 1. Typical Data is for design information only.
2. Negative current is defined as coming out of (sourcing) the specified device terminal.
4
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
V
SENSE
= 0 V, 30 k
I
OUT
=
3964
DUAL FULL-BRIDGE
PWM MOTOR DRIVER
FUNCTIONAL DESCRIPTION
Internal PWM Current Control.
The A3964SB and
A3964SLB contain a fixed off-time pulse-width modulated
(PWM) current-control circuit that can be used to limit the
load current to a desired value. The peak value of the
current limiting (I
TRIP
) is set by the selection of an external
current-sensing resistor (R
S
) and reference input voltage
(V
REF(IN)
). The internal circuitry compares the voltage
across the external sense resistor to the voltage on the
reference input terminal (V
REF(IN)
) resulting in a
transconductance function approximated by:
prevent false over-current detections due to reverse-
recovery currents of the clamp diodes, and/or switching
transients related to distributed capacitance in the load.
During internal PWM operation, at the end of the t
OFF
time, the comparator’s output is blanked and C
T
begins to
be charged from approximately 1.1 volts by an internal
current source of approximately 1 mA. The comparator
output remains blanked until the voltage on C
T
reaches
approximately 3 volts.
V
REF(IN)
When a transition of the PHASE input occurs, C
T
is discharged to near ground during the crossover delay
time (the crossover delay time is present to prevent
simultaneous conduction of the source and sink drivers).
After the crossover delay, C
T
is charged by an internal
current source of approximately 1 mA. The comparator
output remains blanked until the voltage on C
T
reaches
approximately 3 volts.
I
TRIP
≈
R
S
The reference input voltage is typically set with a
resistor divider from V
REF(OUT)
. To ensure proper operation
of the voltage reference, the resistor divider should have
an impedance of 3 k
Ω
to 15 k
Ω
When the device is disabled, via the ENABLE input,
C
T
is discharged to near ground. When the device is
re-enabled, C
T
is charged by an internal current source of
approximately 1 mA. The comparator output remains
blanked until the voltage on C
T
reaches approximately
3 volts.
The current-control circuitry limits the load current as
follows: when the load current reaches I
TRIP
, the compara-
tor resets a latch that turns off the selected source driver.
The load inductance causes the current to recirculate
through the sink driver and flyback diode.
The minimum recommended value for C
T
is
1000 pF.
This value ensures that the blanking time is
sufficient to avoid false trips of the comparator under
normal operating conditions. For optimal regulation of the
load current, the above value for C
T
is recommended and
the value of R
T
can be sized to determine t
OFF
. For more
information regarding load current regulation, see below.
For each bridge, the user selects an external resistor
(R
T
) and capacitor (C
T
) to determine the time period
(t
OFF
= R
T
C
T
) during which the source driver remains
disabled (see “RC Fixed Off-time” below). The range of
recommended values for C
T
and R
T
are 1000 pF to 1500
pF and 15 k
to 100 k
Ω
Load Current Regulation.
Because the device operates
in a slow current-decay mode (2-quadrant PWM mode),
there is a limit to the lowest level that the PWM current
control circuitry can regulate load current. The limitation is
due to the minimum PWM duty cycle, which is a function of
the user-selected value of t
OFF
and the minimum on-time
pulse t
ON(min)
max that occurs each time the PWM latch is
reset. If the motor is not rotating, as in the case of a
stepper motor in hold/detent mode, a brush dc motor when
stalled or at startup, the worst case value of current
regulation can be approximated by:
RC Blanking.
In addition to determining the fixed off-time
of the PWM control circuit, the C
T
component sets the
comparator blanking time. This function blanks the output
of the comparator when the outputs are switched by the
internal current-control circuitry (or by the PHASE or
ENABLE inputs). The comparator output is blanked to
[(V
BB
– V
SAT(SOURCE+SINK)
) x t
ON(min)
max] – [1.05 (V
SAT(SINK)
+ V
F
) x t
OFF
]
I
AVG
≈
1.05 (t
ON(min)
max + t
OFF
) x R
LOAD
www.allegromicro.com
5
(R
D
= R
A
+R
B
). Within this
range, a low impedance will minimize the effect of the REF
IN input offset current.
respectively. For optimal load
current regulation, C
T
is normally set to 1000 pF (see
“Load Current Regulation” below). At the end of the RC
interval, the source driver is enabled allowing the load
current to increase again. The PWM cycle repeats,
maintaining the peak load current at the desired value.
Ω
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