A3946
Half-Bridge Power MOSFET Controller
Features and Benefits
▪
On-chip charge pump for 7 V minimum input
supply voltage
▪
High-current gate drive for driving a wide range of
N-channel MOSFETs
▪
Bootstrapped gate drive with top-off charge pump
for 100% duty cycle
▪
Overtemperature protection
▪
Undervoltage protection
▪
–40ºC to 135ºC ambient operation
Description
The A3946 is designed specifically for applications that require
high power unidirectional DC motors, three-phase brushless DC
motors, or other inductive loads. The A3946 provides two
high-current gate drive outputs that are capable of driving a
wide range of power N-channel
MOSFET
s. The high-side gate
driver switches an N-channel
MOSFET
that controls current to
the load, while the low-side gate driver switches an N-channel
MOSFET
as a synchronous rectifier.
A bootstrap capacitor provides the above-battery supply voltage
required for N-channel MOSFETs. An internal top-off charge
pump for the high side allows DC (100% duty cycle) operation
of the half-bridge.
The A3946 is available in a power package: a 16-lead
TSSOP
with exposed thermal pad (suffix LP). It is lead (Pb) free, with
100% matte tin plated leadframe (suffix -T).
Package: 16-pin TSSOP with exposed
thermal pad (Suffix LP)
Approximate Scale 1:1
Typical Application
V
BAT
VBB
~FAULT
ECU
IN1
IN2
RESET
DT
VREF
LGND
BOOT
GH
A3946
PAD
S
GL
CP1
CP2
VREG
PGND
M
29319.150i
A3946
Half-Bridge Power MOSFET Controller
Selection Guide
Part Number
A3946KLPTR-T
Packing
4000 pieces/reel
Package
16-pin TSSOP with exposed thermal pad
Absolute Maximum Ratings
Characteristic
Load Supply Voltage
Logic Inputs Voltage
Pin S Voltage
Pin GH Voltage
Pin BOOT Voltage
Pin DT Voltage
Pin VREG Voltage
Operating Ambient Temperature
Maximum Junction Temperature
Storage Temperature
ESD Rating, Human Body Model
ESD Rating, Charged Device Model
Symbol
V
BB
V
IN
V
S
V
GH
V
BOOT
V
DT
V
REG
T
A
T
J
(max)
T
stg
AEC-Q100-002, all pins
AEC-Q100-011, all pins
Range K
Notes
Rating
60
–0.3 to 6.5
–4 to 60
–4 to 75
–0.6 to 75
V
REF
–0.6 to 15
–40 to 135
150
–55 to 150
2000
1050
Units
V
V
V
V
V
V
V
ºC
ºC
ºC
V
V
THERMAL CHARACTERISTICS
Characteristic
Package Thermal Resistance
Symbol
R
θJA
Test Conditions*
Mounted on a 2-layer PCB with 3.8 in
2
. 2-oz copper both sides
Mounted on a 4-layer PCB based on JEDEC standard
Value Units
43
34
ºC/W
ºC/W
*Additional thermal information available on Allegro Web site.
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
2
A3946
Half-Bridge Power MOSFET Controller
Functional Block Diagram
+VBAT
C1
0.47 uF, X7R
V rated to VBAT
C2
0.47 uF, X7R
V rated to VBAT
P
VBB
CP2
CP1
VREF
+5 Vref
0.1 uF
X7R
10 V
Charge
Pump
I
LIM
Top-Off
Charge Pump
VREG
C
REG
P
BOOT
10
k
L
L
P
~FAULT
Protection
VREG Undervoltage
Overtemperature
UVLOBOOT
L
VREF
DT
Turn-On
Delay
High Side
Driver
Bootstrap
UVLO
C
BOOT
GH
R
GATE
P
R
DEAD
L
IN1
Control
Logic
VREG
L
S
IN2
Low Side
Driver
GL
R
GATE
PGND
L
RESET
P
L
PAD
LGND
L
P
Control Logic Table
IN1
X
0
0
1
1
0
0
1
1
IN2
X
0
1
0
1
0
1
0
1
DT Pin
X
R
DEAD
- LGND
R
DEAD
- LGND
R
DEAD
- LGND
R
DEAD
- LGND
VREF
VREF
VREF
VREF
RESET
0
1
1
1
1
1
1
1
1
GH
Z
L
L
L
H
L
L
H
H
GL
Z
H
L
L
L
L
H
L
H
Sleep mode
Low-side FET ON following dead time
All OFF
All OFF
High-side FET ON following dead time
All OFF
Low-side FET ON
High-side FET ON
CAUTION: High-side and low-side FETs ON
Function
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A3946
Half-Bridge Power MOSFET Controller
ELECTRICAL CHARACTERISTICS
at T
A
= –40 to +135°C, V
BB
= 7 to 60 V (unless otherwise noted)
Characteristics
Symbol
Test Conditions
RESET = High, Outputs Low
RESET = Low
V
BB
> 7.75 V, I
reg
= 0 mA to 15 mA
V
BB
= 7 V to 7.75 V, I
reg
= 0 mA to 15 mA
CP1, CP2
I
REF
≤
4 mA, C
REF
= 0.1
μF
V
BOOT
– V
S
= 8.5 V
Limits
Min.
Typ.
3
Max.
6
10
13.5
13.5
Units
mA
μA
V
V
kHz
V
μA
V
BB
Quiescent Current
I
VBB
–
–
12.0
11.0
–
13
VREG Output Voltage
Charge Pump Frequency
VREF Output Voltage
Top-Off Charge Pump
Current
V
REG
F
CP
V
REF
I
TO
–
62.5
–
4.5
20
–
5.5
–
–
60
40
4
6
2
3
–
100
80
Gate Output Drive
Turn On Time
Turn Off Time
Pullup On Resistance
t
rise
t
fall
R
DSUP
C
LOAD
= 3300 pF, 20% to 80%
C
LOAD
= 3300 pF, 80% to 20%
T
j
= 25C
T
j
= 135C
T
j
= 25C
T
j
= 135C
t
pw
< 10
μs,
Bootstrap Capacitor fully charged
Pulldown On Resistance
GH Output Voltage
GL Output Voltage
R
DSDOWN
V
GH
V
GL
–
–
–
–
–
–
V
REG
– 1.5
V
REG
– 0.2
ns
ns
V
V
–
8
–
4
–
R
dead
= 5 kΩ
R
dead
= 100 kΩ
Logic input to unloaded GH, GL. DT = VREF
–
–
350
6
–
–
500
7
150
Timing
Dead Time (Delay from
Turn Off to Turn On)
Propagation Delay
t
DEAD
t
PD
200
5
ns
μs
ns
–
–
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
4
A3946
Half-Bridge Power MOSFET Controller
ELECTRICAL CHARACTERISTICS
at T
A
= –40 to +135°C, V
BB
= 7 to 60 V (unless otherwise noted)
Limits
Characteristics
Protection
VREG Undervoltage
V
REGOFF
V
REGON
V
BSOFF
V
BSON
T
JTSD
T
J
V
REG
decreasing
V
REG
increasing
V
BOOT
decreasing
V
BOOT
increasing
Temperature increasing
Recovery = T
JTSD
–
T
J
7.8
8.6
7.25
8
8.3
9.1
7.8
8.75
170
15
8.8
9.6
8.3
9.5
V
V
V
V
°C
°C
Symbol
Test Conditions
Min.
Typ.
Max.
Units
BOOT Undervoltage
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
–
–
–
–
–
2.0
2.2
–
–
100
40
1
Logic
Input Current
I
IN(1)
I
IN(0)
IN1 V
IN
/ IN2 V
IN
= 2.0 V
IN1 V
IN
/ IN2 V
IN
= 0.8 V
RESET pin only
Logic Input Voltage
V
IN(1)
IN1 / IN2 logic high
RESET logic high
V
IN(0)
Logic Input Hysteresis
Fault Output
Logic low
All digital inputs
I = 1 mA, fault asserted
V=5V
40
16
μA
μA
μA
V
V
V
mV
mV
μA
–
100
–
V
ol
V
oh
–
–
–
–
–
–
–
–
–
–
–
0.8
300
400
1
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
5
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