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3976
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 p olarity by selecting the appr opriate
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 100µA.
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 lo ad, motor lead short to
ground or supply, VBB overvoltage, VCC und ervoltage, and thermal
shutdown. If any of these conditions are d etected the outputs will be disabled
and fault information will be output to diagnostic p ins FAULT1 and FAULT2.
The A3976 is supplied in a 24-lead plastic SOIC with a copper
batwing tab ( s uffix ‘LB’).
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 Pa rasitic Free Wheeling Diodes
Crossover Current Protection
4
3
2
1
8
6
7
5
12
11
10
9
21
22
23
24
17
19
18
20
13
14
15
16
ENABLE1
V
BB
PHASE1
NC
NC
GROUND
GROUND
n/c
OUT1A
n/c
FAULT1
OUT1B
PHASE2
NC
V
CC
ENABLE2
FAULT2
OUT2B
OUT2A
n/c
n/c
GROUND
NC
GROUND
A3976KLB
ABSOLUTE MAXIMUM RATINGS
at TA = +25°C
Operating Supply Voltage, VBB ....................27 V
Non-Operating Supply Voltage.................... 35 V
Output Cu rrent, IOUT ............................±500 mA*
Logic Supply Voltage, VCC.......................... 7.0 V
Fault Output Voltage...................................7.0 V
Logic Input Voltage Range,
VIN ......................... -0.3 V to VCC + 0.3 V
Package Power Dissipation (TA = +25°C), PD
A3976KLB..................................2.2 W
Operatin g Temperatu r e Range,
T
A
.............................. -40°C to +125°C
Junction Temperature, TJ......................... +150°C
Stor age 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.
PRELIMINARY DATASHEET - 12/20/01
(Subject to change without notice)
D
UAL FULL BRIDGE
P
ROTECTED MOTOR DRIVER
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
Functional Block Diagram
(one of two bridges shown)
CONTROL
LOGIC
Diagnostic Logic
OUT1A
V
BB
OUT1B
V
CC
GROUND
PHASE1
ENABLE1
To Bridge 2
To Bridge 2
OUT2A
OUT2B
PHASE2
ENABLE2
FAULT1
FAULT2
Thermal
Shutdown
Short to Supply
Monitor
Short to Ground
Monitor
Over/Under
Voltage
Monitor
Input Pull Down
Input Logic
PHASE ENABLE OUTA OUTB
X 0 Off Off
0 1 Low High
1 1 High Low
Fault Logic
Fault Condition FAULT1 FAULT2
Thermal Shutdown Low Low
Short to Battery or Open Load Low High
Short to Ground High Low
Normal Operation High High
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = -40°C to +125°C, VBB = 16V, VCC = 4.5 to 5.5 V (Unless noted otherwise)
Limits
Characteristics Symbol Test Conditions Min. Typ. Max. Units
Output Drivers
Load Supply Voltage Range VBB Operating 6 – 27 V
Logic Suppl y Range VCC Operating 4.5 5.5 V
Output Current Li mit ICL Outputs A or B = GROUND 0.7 1.1 – A
Outputs A or B = VBB 0.7 1.1 – A
Output Leakage Current ICEX VOUT = VBB – <1.0 50 µA
V
OUT = 0 V – <1.0 -50 µA
Output Saturation Vol t age VCE(SAT) Source Driver, IOUT = -350 mA – 1.0 1.2 V
Source Driver, IOUT = -500 mA – 1.2 1.3
Sink Dri ver, IOUT = +350 mA – 0.2 0.4 V
Sink Dri ver, IOUT = +500 mA – 0.4 0.6 V
Clamp Di ode Forward Volt age VF IF = 500 m A (Sink / Ground Cl amp) – 1.2 1.5 V
(Flyback or Ground Clamp) IF = 500 mA (Source / Flyback) – 1.55 2.0 V
Control Logic
Motor Supply Current IBB ENABLE1 = ENABLE2 = High – 7 10 mA
(No Load) Sleep Mode ENAB LE 1 = ENABLE2 = Low – – 25 µA
Logic Suppl y Current ICC ENABLE1 = ENABLE2 = High – 45 50 mA
Sleep Mode, ENA B LE1 = ENABLE 2 = Low – – 75 µA
Logic Input Voltage VIN(1) 0.7VCC – - V
V
IN(0) – – .3VCC V
Logic Input Current IIN(1) V
IN = 5 V – 50 100 µ A
I
IN(0) V
IN = 0 V – -1.0 -2.0 µA
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
ELECTRICAL CHARACTERISTICS at TA = -40°C to +125°C, VBB = 16 V, VCC = 4.5 to 5.5 V (Unless noted otherwise)
Limits
Characteristics Symbol Test Conditions Min. Typ. Max. Units
Fault Circuitry
Fault Output Leakage Current IF-LEAK V
F
= 5 V, No Fault s - - 10 µA
Fault Output V ol t age VFL Fault Condit i on A sserted, IF = 25 µA – 0.8 V
Fault Output Current IF V
F
= 5 V, ENA BLE = High 25 50 75 µA
Output Open Load Current I OUT-O.L. V
BB = 12 V – 2 – mA
Thermal Fault Temp. TF – 170 – °C
Thermal Faul t Hysteres i s TFHYS – 10 – °C
OVLO Enable Threshol d VBB rising 27 30 33 V
OVLO Hysteresis 1.5 V
UVLO Enable Thres hol d VCC ris i ng 3.5 4 4.49 V
UVLO Hysteresis – 400 – mV
Timing
Open Fault to Reset Delay trs V
BB = 12 V – – 25 µs
PHASE_X Delay to OPEN Fault tof V
BB = 12 V – 8 – µs
PHASE_X Delay to S.C. Fault tSC V
BB = 12 V – 5 – µs
ENABLE_X Delay to Fault tof V
BB = 12 V – 5 – µs
Propagation Delay Ti mes tpd I
OUT = ±0.35A, 50%TO 90%
ENABLE ON TO SOURCE ON – 0.3 µs
ENABLE OF F TO S O URCE OF F – 0.4 µs
ENABLE ON TO SINK ON – 0.3 µs
ENABLE OFF TO SINK OFF – 0.2 µs
PHASE CHANGE TO SINK ON – 4.0 µs
PHASE CHANGE TO SINK OFF – 0.3 µs
PHASE CHANGE TO SOURCE ON – 4.0 µs
PHASE CHANGE TO SOURCE OFF – 0.4 µs
Cross Over Dead Time tCODT 1KΩ (1k+1k) Load (VBB to OUT to GND) 0.5 3.0 6.0 µs
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3976 – DUAL FULL BRIDGE
PROTECTED MOTOR DRIVER
APPLICATION NOTES
Open Load Protecti on. During no rmal PWM
operation, d iagno stic 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 lo gic will signal a fault and disable the o utputs 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.
Short Circuit Prot ection. Internal sense re sistors in
series with VBB 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 5 µs 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.
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, VBB, should be decoupled
with an electrolytic capacitor (> 47 µF is recommended)
placed as close to the device as possible.
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3976 - DUAL FULL BRIDGE
PROTCTED MOTOR DRIVER
Terminal List
Name Description SOIC - 24
VBB Motor Supply Voltage 1
ENABLE1 Control Logic – Bridge 1 2
PHASE1 Control Logic – Bridge 1 3
GROUND Power Ground Return 18,19,6,7
OUT1A Bridge 1 Output A 9
FAULT1 Diagnostic Output 11
OUT1B Bridge 1 Output B 12
OUT2B Bridge 2 Output B 13
FAULT2 Diagnostic Output 14
OUT2A Bridge 2 Output A 16
PHASE2 Control Logic – Bridge 2 22
ENABLE2 Control Logic – Bridge 2 23
VCC Logic Supply 24
NC No Connect 4,5,8,15,17,20,21
