A4957
Full Bridge MOSFET Driver
Features and Benefits
▪
High current gate drive for N-channel MOSFET full bridge
▪
Independent control of each MOSFET
▪
Charge pump for low supply voltage operation
▪
Cross-conduction protection with adjustable dead time
▪
4.5 to 50 V supply voltage range
▪
Diagnostics output
▪
Low current sleep mode
Description
The A4957 is a full-bridge controller for use with external
N-channel power MOSFETs and is specifically designed for
applications with high-power inductive loads such as brush
DC motors.
A unique charge pump regulator provides full ( >10 V ) gate
drive for battery voltages down to 7 V and allows the A4957
to operate with a reduced gate drive, down to 4.5 V.
A bootstrap capacitor is used to provide the above battery
supply voltage required for N-channel MOSFETs. A unique
bootstrap charge management system ensures that the bootstrap
capacitor is always sufficiently charged to supply the high-side
gate drive circuit.
Each of the power MOSFETs is controlled independently but
all are protected from shoot-through by dead time that is user-
configured by an external resistor.
Integrated diagnostics provide indication of undervoltage and
overtemperature faults.
The A4957 is supplied in a 24-contact
4 mm × 4 mm × 0.75 mm
QFN with an exposed pad for enhanced thermal dissipation.
It is lead (Pb) free, with 100% matte tin leadframe plating
(suffix –T).
Package: 24-contact QFN with exposed
thermal pad (Suffix ES)
Not to scale
Typical Application
FAULT
VBAT
AHI
BHI
A4957
M
ALO
BLO
A4957-DS
A4957
Full Bridge MOSFET Driver
Selection Guide
Part Number
A4957SESTR-T
Packing
1500 pieces per reel
Absolute Maximum Ratings*
Characteristic
Load Supply Voltage
Logic Supply Voltage
Logic Inputs
Logic Outputs
Pin VREG
Pins CP1, CP2
Pin RDEAD
Pins SA, SB
Pins GHA, GHB
Pins GLA, GLB
Pins CA, CB
ESD Rating, Human Body Model
ESD Rating, Charged Device Model
Ambient Operating Temperature
Range
Continuous Junction Temperature
Transient Junction Temperature
Storage Temperature Range
*With respect to ground
T
A
T
J
(max)
T
Jt
T
stg
Overtemperature event not exceeding
10 s, lifetime duration not exceeding 10 hr,
guaranteed by design characterization
Symbol
V
BB
V
DD
V
I
V
O
V
VREG
V
CPX
V
RDEAD
V
SX
V
GHX
V
GLX
V
CX
AEC Q100-002, all pins
AEC Q100-011, all pins
Range S
Notes
Rating
–0.3 to 50
–0.3 to 7
–0.3 to 6.5
–0.3 to 6.5
–0.3 to 16
–0.3 to 16
–0.3 to 6.5
–5 to 55
V
SX
to V
SX
+ 15
–5 to 16
–0.3 to V
SX
+15
2000
1000
–20 to 85
150
175
–55 to 150
Unit
V
V
V
V
V
V
V
V
V
V
V
V
V
°C
°C
°C
°C
Thermal Characteristics
may require derating at maximum conditions, see application information
Characteristic
Package Thermal Resistance, Junc-
tion to Ambient
Package Thermal Resistance, Junc-
tion to Pad
Symbol
R
θJA
R
θJP
Test Conditions*
Estimated, on 4-layer PCB based on JEDEC standard
Value
37
2
Unit
ºC/W
ºC/W
*Additional thermal information available on the Allegro website
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A4957
Full Bridge MOSFET Driver
Functional Block Diagram
Battery +
C
P
VBB
VDD
CP2
CP1
Charge
Pump
Regulator
Diagnostics &
Protection
Bootstrap
Monitor
CA
GHA
R
GHA
SA
AHI
ALO
Low
Side
GND
Bootstrap
Monitor
GLA
R
GLA
R
GLB
R
GHB
VREG
C
REG
V
BAT
FAULT
C
BOOTA
High
Side
Control
Logic
BHI
CB
C
BOOTB
BLO
High
Side
GHB
SB
RESET
Low
Side
GND
RDEAD
AGND
GND
GLB
Thermal Pad
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A4957
Full Bridge MOSFET Driver
ELECTRICAL CHARACTERISTICS
Valid at T
A
= 25°C, V
BB
= 17 V, V
DD
= 3 to 5.5 V; unless otherwise noted
Characteristics
Supply and Reference
V
BB
Functional Operating Range
1
V
DD
Range
V
BB
Quiescent Current
V
DD
Quiescent Current
V
BB
V
DD
I
BBQ
I
BBS
I
VDDQ
I
VDDS
RESET = high, GHx, GLx = low, V
BB
= 12 V
RESET= low, V
BB
= 12 V
RESET = high, outputs low
RESET = low
V
BB
> 9 V, I
REG
= 0 to 8 mA
7.5 V < V
BB
≤
9 V, I
REG
= 0 to 6 mA
VREG Output Voltage
V
REG
6 V < V
BB
≤
7.5 V, I
REG
= 0 to 5 mA
4.5 V < V
BB
≤
6 V, I
REG
< 4 mA
Bootstrap Diode Forward Voltage
Bootstrap Diode Resistance
Bootstrap Diode Current Limit
Gate Output Drive
Turn-On Time
Turn-Off Time
Pull-up On Resistance
Pull-down On Resistance
GHx Output Voltage
GLx Output Voltage
Turn-Off Propagation Delay
2
Turn-On Propagation Delay
2
Propagation Delay Matching - Phase to
Phase
Propagation Delay Matching - On to Off
t
r
t
f
R
DS(on)UP
R
DS(on)DN
V
GH
V
GL
t
p(off)
t
p(on)
Δt
PP
Δt
OO
Input change to unloaded gate output change
Input change to unloaded gate output change
Same phase change
Single phase
RDEAD tied to GND
R
DEAD
= 3 kΩ
Dead Time
2
t
DEAD
R
DEAD
= 30 kΩ
R
DEAD
= 240 kΩ
RDEAD tied to VDD
C
LOAD
= 1 nF, 20% to 80% points
C
LOAD
= 1 nF, 80% to 20% points
T
J
= 25°C, I
GHX
= –150 mA
T
J
= 150°C, I
GHX
= –150 mA
T
J
= 25°C, I
GLX
= –150 mA
T
J
= 150°C, I
GLX
= –150 mA
Bootstrap capacitor fully charged
–
–
8
13
3
6
V
CX
– 0.2
V
REG
– 0.2
60
60
–
–
–
–
815
–
–
35
20
11
18.5
6
9
–
–
90
90
10
10
0
180
960
3.5
6
–
–
16
24
8
12
–
–
150
150
–
–
–
–
1150
–
–
ns
ns
Ω
Ω
Ω
Ω
V
V
ns
ns
ns
ns
ns
ns
ns
μs
μs
V
fBOOT
r
D
I
DBOOT
I
D
= 10 mA
I
D
= 100 mA
r
D(100mA)
=
(V
fBOOT(150mA)
– V
fBOOT(50mA)
) / 100 mA
4.5
3
–
–
–
–
12.65
12.65
2
×
V
BB
– 2.5
6.5
0.4
1.5
6
250
–
–
1
–
2
–
13
13
–
9.5
0.7
2.2
10
500
50
5.5
2
10
4
10
13.9
13.9
–
–
1.0
2.8
20
750
V
V
mA
μA
mA
μA
V
V
V
V
V
V
Ω
mA
Symbol
Test Conditions
Min.
Typ.
Max.
Unit
Continued on the next page…
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A4957
Full Bridge MOSFET Driver
ELECTRICAL CHARACTERISTICS
(continued)
Valid at T
A
= 25°C, V
BB
= 17 V, V
DD
= 3 to 5.5 V; unless otherwise noted
Characteristics
Logic Inputs and Outputs
FAULT Output (Open drain)
FAULT Output Leakage Current
3
RDEAD Current
3
Input Low Voltage
Input High Voltage
Input Hysteresis
Input Current (Except RESET)
3
Input Pull-down Resistor (RESET)
RESET Pulse Time
Protection
VREG Undervoltage Lockout
Bootstrap Undervoltage
Bootstrap Undervoltage Hysteresis
VDD Undervoltage Turn-Off
VDD Undervoltage Hysteresis
Overtemperature Flag
Overtemperature Hysteresis
1
Function
2
See
Symbol
V
OL
I
OH
I
DEAD
V
IL
V
IH
V
IHYS
I
IN
R
PD
t
RES
V
REGUVON
V
BOOTUV
V
BOOTUVHYS
V
DDUV
V
DDUVHYS
T
JF
T
JFHYS
V
DD
falling
V
REG
rising
0 V < V
IN
< V
DD
Test Conditions
I
FAULTOL
= 1 mA, fault present
V
FAULTO
= 5 V, fault not present
RDEAD = GND
Min.
–
–1
–200
–
0.7
×
V
DD
300
–1
–
0.1
5.85
5.24
75
–
2.45
50
150
–
Typ.
–
–
–
–
–
500
–
50
Max.
0.4
1
–70
0.3
×
V
DD
–
–
1
–
3.5
Unit
V
μA
μA
V
V
mV
μA
kΩ
μs
V
V
%V
REG
%V
REG
V
mV
ºC
ºC
6.2
5.54
–
20
2.7
100
170
15
6.5
5.85
85
–
2.85
150
–
–
V
REGUVOFF
V
REG
falling
V
BOOT
falling, V
CX
– V
SX
Temperature increasing
Recovery = T
JF
– T
JFHYS
is correct, but parameters are not guaranteed below the general limit (7 V).
Gate Drive Timing.
3
For input and output current specifications, negative current is defined as coming out of (sourcing) the specified device pin.
Gate Drive Timing Diagrams
xHI
xLO
t
p(off)
GHx
GLx
t
DEAD
t
p(off)
Complementary
High side only
t
DEAD
GHx
GLx
xHI
xLO
t
p(on)
t
p(off)
GHx
GLx
t
p(on)
t
p(off)
xHI
xLO
Low side only
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
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