A4936
3-Phase Brushless DC Motor Pre-Driver
Features and Benefits
• Drives 6 N-channel MOSFETs
• Synchronous rectification for low power dissipation
• Internal UVLO and thermal shutdown circuitry
• Hall element inputs
• PWM current limiting
• Dead time protection
• FG outputs
• Standby mode
• Lock detect protection
• Overvoltage protection
Description
The A4936 is a complete 3-phase brushless DC motor pre-driver,
supplying up to 28 V output for direct, high-current gate drive
of an all N-channel power MOSFET 3-phase bridge. The device
has three Hall-element inputs, a sequencer for commutation
control, fixed off-time pulse width modulation (PWM) current
control, and locked-rotor detection.
Output current is scaled by the capability of the external
MOSFETs. Locked rotor detection delay is set by an external
capacitor on the CLD terminal. The PWM, DIR, and BRAKE
and STOP inputs can be used to control motor speed, position,
and torque. Motor speed can be determined using the FG output
from an FG coil amplifier and comparator.
The external MOSFETS can be PWMed using an external
signal on the PWM input, or using the internal PWM current
regulator. In either case, the A4936 synchronous rectification
feature reduces power dissipation by turning-on the appropriate
MOSFETs during current decay.
The Hall elements can be inexpensive types, when used with
noise filtering to prevent false commutation signals. The
A4936 provides a regulated 7.5 V supply to power the three
Hall elements.
Package: 32-contact QFN (suffix ET)
Not to scale
Continued on the next page…
Typical Application Diagram
V+
System
Control
Logic
BLDC
Motor
A4936
A4936-DS
A4936
Description (continued)
3-Phase Brushless DC Motor Pre-Driver
Internal circuit protection includes thermal shutdown with hysteresis,
undervoltage lockout, and dead time protection. Special power-up
sequencing is not required. Operating temperature range is –20°C
to 105°C.
The device package is a 32-contact, 5 mm × 5 mm, 0.90 mm
nominal overall height QFN, with exposed pad for enhanced thermal
dissipation. This small-footprint package is lead (Pb) free, with 100%
matte tin leadframe plating.
Selection Guide
Part Number
Packing*
Package
32-pin QFN, 5 mm × 5 mm,
0.90 mm nominal overall height
A4936MET-T
73 pieces per tube
A4936METTR-T
1500 pieces per reel
*Contact Allegro
®
for additional packing options
Absolute Maximum Ratings
Characteristic
Load Supply Voltage
Motor Phase Output
Hall Input
Logic Input Voltage Range
Ambient Operating Temperature
Maximum Junction Temperature
Storage Temperature
Symbol
V
BB
S
x
V
Hx
V
IN
T
A
T
J
(max)
T
stg
Range M
t
w
< 500 ns
DC
Notes
Rating
38
–3
–0.3 to 7
–0.3 to 7
–20 to 105
150
–40 to 150
Unit
V
V
V
V
°C
°C
°C
Thermal Characteristics
may require derating at maximum conditions, see application information
Characteristic
Package Thermal Resistance
(Junction to Ambient)
Package Thermal Resistance
(Junction to Exposed Pad)
Symbol
R
θJA
R
θJP
Test Conditions*
On 4-layer PCB based on JEDEC standard
Value
32
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
A4936
3-Phase Brushless DC Motor Pre-Driver
Functional Block Diagram
100 nF
CP1
100 nF
100 nF
CLD
HBIAS
2 kΩ
HA+
HA–
Commun-
ication
Logic
Control
Logic
Lock
Detect
VREG
OVP
Enable
V
REG
Phase A
Gate
Drive
V
CP
GHA
SA
GLA
Charge
Pump
CP2
VCP
VBB
100 nF
100 nF
V
IN
Pin-out Diagram
HA+
BRAKE
STOP
PWM
DIR
CLD
FGS
SA
HALL
HALL
HB+
HB–
HC+
HC–
32
31
30
29
28
27
26
25
HA–
HB+
HB–
HC+
HC–
FG+
FGFB
FG–
1
2
3
4
5
6
7
8
PAD
24 GHA
23 SB
22 GHB
21 SC
20 GHC
19 GLA
18 GLB
17 GLC
System
Logic
BRAKE
STOP
DIR
PWM
FGS
GND
NC 9
GND 10
HBIAS 11
CP1 12
CP2 13
VBB 14
VCP 15
SENSE 16
Terminal List Table
Number
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
Name
HA-
HB+
HB-
HC+
HC-
FG+
FGFB
FG-
NC
GND
HBIAS
CP1
CP2
VBB
VCP
SENSE
GLC
Hall input A
Hall input B
Hall input B
Hall input C
Hall input C
FG input
FG amplifier feedback output
FG input
No internal connection
Ground
Hall bias power supply output
Charge pump capacitor terminal
Charge pump capacitor terminal
Supply voltage
Reservoir capacitor terminal
Sense resistor connection
Low-side gate drive C
Function
Number
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
–
Name
GLB
GLA
GHC
SC
GHB
SB
GHA
SA
FGS
CLD
DIR
PWM
STOP
BRAKE
HA+
PAD
Function
Low-side gate drive B
Low-side gate drive A
High-side gate drive C
High-side source connection C
High-side gate drive B
High-side source connection B
High-side gate drive A
High-side source connection A
FG output
Locked rotor detect timing capacitor
Logic input: motor direction
Logic input: external PWM control
Logic input: output disable
Logic input: motor brake
Hall input A
Exposed Thermal Pad
–
HALL
+
200 mV
SENSE
GHB
SB
GLB
GHC
SC
GLC
FGFB
Phase A of three
phases shown
–
+
FG–
FG+
Allegro MicroSystems, Inc.
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
3
A4936
3-Phase Brushless DC Motor Pre-Driver
ELECTRICAL CHARACTERISTICS
1,2
Valid at T
A
= 25°C, V
IN
= 24 V; unless otherwise noted
Characteristics
General
Supply Voltage Range
Motor Supply Current
HBIAS
HBIAS Current Limit
Control Logic
Logic Input Voltage
Logic Input Current
Input Pin Glitch Reject
HBIAS Wake-up Delay, Standby Mode
Gate Drive
High-Side Gate Drive Output
Low-Side Gate Drive Output
Gate Drive Current (Sourcing)
Gate Drive Pull-Down Resistance
Dead Time
Current Limit Input Threshold
Fixed Off-Time
Protection
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
VBB UVLO Enable Threshold
VBB UVLO Hysteresis
VCP UVLO
Lock Detect Duration
VBB Overvoltage Threshold
Hall Logic
Hall Input Current
Common Mode Input Range
AC Input Voltage Range
Hall Thresholds
Hall Threshold Hysteresis
Pulse Reject Filter
I
HALL
V
CMR
V
HALL
V
th
V
HYS
t
pulse
Difference between Hall inputs at transitions
T
J
= 25°C
T
J
= –20°C to 125°C
V
IN
= 0.2 to 3.5 V
–1
0.2
60
–
10
5
–
0
–
–
+10, –10
20
20
2
1
3.5
–
–
30
40
–
μA
V
mV
p-p
mV
mV
mV
μs
T
JTSD
T
JTSDhys
V
BBUV
V
BBUVhys
V
CPUV
t
lock
V
BBOV
Relative to V
BB
, VCP falling
C = 0.1
μF
Rising V
BB
Rising V
BB
155
–
6.2
0.4
4.6
1.5
30
170
20
7
0.75
–
2
33
185
–
7.85
1
6
2.5
37.5
°C
°C
V
V
V
s
V
V
GS(H)
V
GS(L)
I
GATE
R
GATE
t
DEAD
V
REF
t
OFF
Relative to V
BB
, I
GATE
= 2 mA
I
GATE
= 2 mA
GHx = GLx = 4 V
7
7
20
10
700
180
18
–
–
30
28
1000
200
25
–
–
–
40
1300
220
37
V
V
mA
Ω
ns
mV
μs
V
IN(1)
V
IN(0)
I
IN(1)
I
IN(0)
t
GLITCH
t
dHBIAS
V
IN
= 2 V
V
IN
= 0.8 V
PWM pin
DIR, BRAKE, and STOP pins
C
HBIAS
= 0.1
μF
2
–
–1.0
–1.0
350
700
–
–
–
<1.0
<–1.0
500
1000
15
–
0.8
1.0
1.0
650
1300
25
V
V
μA
μA
ns
ns
μs
V
BB
I
BB
V
HBIAS
I
HBIASlim
Operating
f
PWM
< 30 kHz, C
LOAD
= 1000 pF
Standby mode
0 mA
≤
I
HBIAS
≤
24 mA
8.5
–
–
7.2
30
–
5.1
3
7.5
–
V
BBOV
6.5
4
7.8
–
V
mA
mA
V
mA
Symbol
Test Conditions
Min.
Typ.
3
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
A4936
Characteristics
FG
FG Input Bias Current
FG Input Offset Voltage
FGS Output High Leakage
FGS Output Low Voltage
FG Amp Open Loop Gain
FG Amp Bias Voltage
FG Comparator Hysteresis
1
For
2
Specifications
3-Phase Brushless DC Motor Pre-Driver
Symbol
I
BFG
V
OSFG
I
OH
V
OL
A
FG
V
BFG
V
FGhys
V
OH
= 5 V
I
OL
= 2 mA
Test Conditions
Min.
–1
–15
–1
–
45
2.2
40
Typ.
3
–
–
–
0.2
60
2.5
110
Max.
1
15
1
0.4
–
2.8
160
Unit
μA
mV
μA
V
dB
V
mV
ELECTRICAL CHARACTERISTICS
1,2
(continued) Valid at T
A
= 25°C, V
IN
= 24 V; unless otherwise noted
input and output current specifications, negative current is defined as coming out of (sourcing) the specified device pin.
throughout the allowed operating temperature range are guaranteed by design and characterization.
3
Typical data are for initial design estimations only, and assume optimum manufacturing and application conditions. Performance may vary for
individual units, within the specified maximum and minimum limits.
Logic States Table*
(See timing charts, below)
Condition
A
B
C
Forward
D
E
F
A
B
C
Reverse
D
E
F
HA
HB
HC
DIR
STOP
+
–
+
1
0
+
–
–
1
0
+
+
–
1
0
–
+
–
1
0
–
+
+
1
0
–
–
+
1
0
+
–
+
0
0
+
–
–
0
0
+
+
–
0
0
–
+
–
0
0
–
+
+
0
0
–
–
+
0
0
–
–
–
X
X
Fault
+
+
+
X
X
Brake
X
X
X
X
0
Coast
X
X
X
X
1
Standby
X
X
X
X
1
*X = Don’t care (can be 1 or 0), Z = High impedance
DIR = 1 = Forward
A
HA
HB
HC
B
C
D
E
F
HA
HB
HC
A
B
BRAKE
0
0
0
0
0
0
0
0
0
0
0
0
X
X
1
0
1
PWM
1
1
1
1
1
1
1
1
1
1
1
1
X
X
X
X
X
GHA
HI
HI
LO
LO
LO
LO
LO
LO
LO
HI
HI
LO
LO
LO
LO
LO
LO
GLA
LO
LO
LO
HI
HI
LO
HI
HI
LO
LO
LO
LO
LO
LO
HI
LO
LO
GHB
LO
LO
HI
HI
LO
LO
HI
LO
LO
LO
LO
HI
LO
LO
LO
LO
LO
GLB
HI
LO
LO
LO
LO
HI
LO
LO
HI
HI
LO
LO
LO
LO
HI
LO
LO
GHC
LO
LO
LO
LO
HI
HI
LO
HI
HI
LO
LO
LO
LO
LO
LO
LO
LO
GLC
LO
HI
HI
LO
LO
LO
LO
LO
LO
LO
HI
HI
LO
LO
HI
LO
LO
SA
HI
HI
Z
LO
LO
Z
LO
LO
Z
HI
HI
Z
Z
Z
LO
Z
Z
SB
LO
Z
HI
HI
Z
LO
HI
Z
LO
LO
Z
HI
Z
Z
LO
Z
Z
SC
Z
LO
LO
Z
HI
HI
Z
HI
HI
Z
LO
LO
Z
Z
LO
Z
Z
DIR = 0 = Reverse
C
D
E
F
SA
SA
SB
SC
SB
SC
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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