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3976
PRELIMINARY DATASHEET - 12/20/01
(Subject to change without notice)
DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
The A3976 is designed to drive both windings of a bipolar stepper
motor or bidirectionally control two DC Motors. Both H-Bridges are capable
of continuous output currents of up to +/- 500 mA and operating voltages to
27V. Free wheeling, substrate isolated diodes are included for output transient
suppression when switching motors or other inductive loads. For each bridge
the PHASE input controls load current polarity by selecting the appropriate
source and sink driver pair. The ENABLE input, when held high, enables the
respective output H-bridge. When both ENABLE pins are held low the device
will enter SLEEP mode and consume less than 100
µ
A.
The A3976 is protected to ensure safe operation in harsh operating
environments and was designed specifically for automotive applications.
Protection circuitry will check for open or shorted load, motor lead short to
ground or supply, VBB overvoltage, VCC undervoltage, and thermal
shutdown. If any of these conditions are detected the outputs will be disabled
and fault information will be output to diagnostic pins FAULT1 and FAULT2.
The A3976 is supplied in a 24-lead plastic SOIC with a copper
batwing tab (suffix ‘LB’).
V
BB
1
ENABLE1
PHASE1
NC
NC
GROUND
GROUND
n/c
OUT1A
2
3
4
5
6
7
8
9
2 4 V
CC
2 3 ENABLE2
2 2 PHASE2
2 1 NC
2 0 NC
A3976KLB
1 9 GROUND
1 8 GROUND
1 7 n/c
1 6 OUT2A
1 5 n/c
1 4 FAULT2
1 3 OUT2B
n/c 1 0
FAULT1
OUT1B
11
12
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
Operating Supply Voltage, V
BB
....................
27 V
Non-Operating Supply Voltage ....................
35 V
Output Current, I
OUT
............................±500
mA*
Logic Supply Voltage, V
CC
..........................
7.0 V
Fault Output Voltage ...................................
7.0 V
Logic Input Voltage Range,
V
IN
.........................
-0.3 V to V
CC
+ 0.3 V
Package Power Dissipation (TA = +25°C), P
D
A3976KLB..................................
2.2 W
Operating Temperature Range,
T
A
..............................
-40°C to +125°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.
T
T
T
T
T
T
T
T
T
T
T
FEATURES
±500 mA Continuous Output Rating
35V Load Dump Survival
Output Short Circuit Protection
Coded Fault Diagnostic Outputs
Low Current Standby Mode
Open Load Monitor
Low Current Standby Mode
VBB Over Voltage Shutdown
Internal Thermal Shutdown Circuitry
Internal Low Parasitic Free Wheeling Diodes
Crossover Current Protection
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
Functional Block Diagram
(one of two bridges shown)
V
CC
Thermal
Shutdown
Over/Under
Voltage
Monitor
Short to Supply
Monitor
V
BB
FAULT1
Diagnostic Logic
FAULT2
To Bridge 2
PHASE1
OUT1A
ENABLE1
PHASE2
CONTROL
LOGIC
OUT1B
ENABLE2
OUT2A
Input Pull Down
To Bridge 2
OUT2B
GROUND
Short to Ground
Monitor
Input Logic
PHASE
X
0
1
ENABLE
0
1
1
OUTA
Off
Low
High
OUTB
Off
High
Low
Fault Logic
Fault Condition
Thermal Shutdown
Short to Battery or Open Load
Short to Ground
Normal Operation
FAULT1
Low
Low
High
High
FAULT2
Low
High
Low
High
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = -40°C to +125°C, VBB = 16V, V
CC
= 4.5 to 5.5 V
(Unless noted otherwise)
Limits
Characteristics
Output Drivers
Load Supply Voltage Range
Logic Supply Range
Output Current Limit
V
BB
V
CC
I
CL
Operating
Operating
Outputs A or B = GROUND
Outputs A or B = V
BB
Output Leakage Current
I
CEX
VOUT = V
BB
VOUT = 0 V
Output Saturation Voltage
V
CE(SAT)
Source Driver, I
OUT
= -350 mA
Source Driver, I
OUT
= -500 mA
Sink Driver, I
OUT
= +350 mA
Sink Driver, I
OUT
= +500 mA
Clamp Diode Forward Voltage
(Flyback or Ground Clamp)
Control Logic
Motor Supply Current
(No Load)
Logic Supply Current
I
CC
I
BB
ENABLE1 = ENABLE2 = High
Sleep Mode ENABLE1 = ENABLE2 = Low
ENABLE1 = ENABLE2 = High
Sleep Mode, ENABLE1 = ENABLE2 = Low
Logic Input Voltage
V
IN(1)
V
IN(0)
Logic Input Current
I
IN(1)
I
IN(0)
V
IN
= 5 V
V
IN
= 0 V
–
–
–
–
0.7V
CC
–
–
–
7
–
45
–
–
–
50
-1.0
10
25
50
75
-
.3V
CC
100
-2.0
mA
µA
mA
µA
V
V
µA
µA
V
F
IF = 500 mA (Sink / Ground Clamp)
IF = 500 mA (Source / Flyback)
6
4.5
0.7
0.7
–
–
–
–
–
–
–
–
1.1
1.1
<1.0
<1.0
1.0
1.2
0.2
0.4
1.2
1.55
–
27
5.5
–
–
50
-50
1.2
1.3
0.4
0.6
1.5
2.0
V
V
V
V
V
V
A
A
µA
µA
V
Symbol
Test Conditions
Min.
Typ.
Max.
Units
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = -40°C to +125°C, VBB = 16 V, V
CC
= 4.5 to 5.5 V
(Unless noted otherwise)
Limits
Characteristics
Symbol
Test Conditions
Min.
Typ.
Max.
Units
Fault Circuitry
Fault Output Leakage Current
Fault Output Voltage
Fault Output Current
Output Open Load Current
Thermal Fault Temp.
Thermal Fault Hysteresis
OVLO Enable Threshold
OVLO Hysteresis
UVLO Enable Threshold
UVLO Hysteresis
Timing
Open Fault to Reset Delay
PHASE_X Delay to OPEN Fault
PHASE_X Delay to S.C. Fault
ENABLE_X Delay to Fault
Propagation Delay Times
t
rs
t
of
t
SC
t
of
tpd
V
BB
= 12 V
V
BB
= 12 V
V
BB
= 12 V
V
BB
= 12 V
IOUT = ±0.35A, 50%TO 90%
ENABLE ON TO SOURCE ON
ENABLE OFF TO SOURCE OFF
ENABLE ON TO SINK ON
ENABLE OFF TO SINK OFF
PHASE CHANGE TO SINK ON
PHASE CHANGE TO SINK OFF
PHASE CHANGE TO SOURCE ON
PHASE CHANGE TO SOURCE OFF
Cross Over Dead Time
t
CODT
1KΩ (1k+1k) Load (V
BB
to OUT to GND)
–
–
–
–
–
–
–
–
0.5
0.3
0.4
0.3
0.2
4.0
0.3
4.0
0.4
3.0
6.0
µs
µs
µs
µs
µs
µs
µs
µs
µs
–
–
–
–
–
8
5
5
25
–
–
–
µs
µs
µs
µs
V
CC
rising
3.5
–
I
F-LEAK
V
FL
I
F
I
OUT-O.L.
T
F
T
FHYS
V
BB
rising
V
F
= 5 V, No Faults
Fault Condition Asserted, I
F
= 25
µA
V
F
= 5 V, ENABLE = High
V
BB
= 12 V
25
–
–
–
27
-
-
–
50
2
170
10
30
1.5
4
400
4.49
–
10
0.8
75
–
–
–
33
µA
V
µA
mA
°C
°C
V
V
V
mV
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
APPLICATION NOTES
Open Load Protection.
During normal PWM
operation, diagnostic circuitry will look for a minimum
source current level after a bridge is signalled on.
Additionally, the diode flyback is monitored on the proper
output. The logic will signal a fault and disable the outputs if
it determines that the current is below the minimum level
AND no flyback is occurring. If the inductive load is too
large, the current would take too long to reach the minimal
level and a false open load would be reported. It is
recommended that the inductive load be less than 38 mH.
Layout.
The printed wiring board should use a heavy
ground plane. For optimum electrical and thermal
performance, the driver should be soldered directly onto the
board. The load supply terminal, V
BB
, should be decoupled
with an electrolytic capacitor (> 47 µF is recommended)
placed as close to the device as possible.
Short Circuit Protection.
Internal sense resistors in
series with V
BB
and ground will trip the fault circuitry if
greater than 1.1 A is detected. To prevent false overcurrent
events due to reverse recovery spikes of the clamp diodes,
the current monitor is blanked for 5µs after a high side is
signalled to turn on. If an additional input command follows
after the initial fault, the selected pair of drivers will pulse on
for the 5µs blanking duration. The short circuit fault will
remember the input state where the fault occurred and will
wait for that particular logic state after the short has been
removed before normal operation is allowed to resume.
Thermal Protection
.
Circuitry turns OFF all drivers
when the junction temperature reaches 170°C typically. It is
intended only to protect the device from failures due to
excessive junction temperatures and has a hysteresis of
approximately 15°C.
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