DESCRIPTION
The A3909 is a dual full bridge motor driver, designed for
12 V medium power applications. The outputs are rated for
operation through a power supply range of 4 to 18 V, and
capable of up to 1 A per phase.
Paralleling the outputs is possible for higher amperage single
DC motor applications.
The four inputs (IN1 to IN4) can control DC motors in forward,
reverse, brake, and coast modes, or a bipolar stepper motor in
full- and half-step modes.
The A3909 is supplied in a 10-pin MSOP package with exposed
thermal pad (suffix LY) and a 10-pin SSOP (suffix LN) for
wave solder applications. Both packages are lead (Pb) free
with 100% matte-tin leadframe plating.
A3909-DS, Rev. 1
MCO-0000529
FEATURES AND BENEFITS
• Low RDS(on) outputs
• Drives two DC motors or single stepper motor
• Low power standby (Sleep) mode with zero current drain
• Thermal shutdown protection
• Parallel operation option for 1.8 A, single DC motor
• Overcurrent protection:
▫Outputtosupplyshort
▫OutputtoGNDshort
▫Outputloadshort
Dual Full Bridge Motor Driver
PACKAGES:
Functional Block Diagram
Not to scale
A3909
Control
Logic
GND
OUT1
OUT2
VBB
VBB
VBB
IN1
IN2
Load Supply Load Supply
Configuration
for driving
2 DC motors
TSD
Disable UVLO
OCP
Control
Logic
GND
OUT3
OUT4
VBB
IN3
IN
PAD
LY package
4
TSD
Disable UVLO
OCP
OUT1
OUT2
VBB
Configuration
for parallel operation
at 1.8 A
OUT3
OUT4
GND
10-pin MSOP
with exposed thermal pad
(LY package)
10-pin SSOP
(LN package)
November 15, 2018
Dual Full Bridge Motor Driver
A3909
2
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Pinout Diagram
ABSOLUTE MAXIMUM RATINGS
Characteristic Symbol Notes Rating Unit
Supply Voltage VBB 18 V
Logic Input Voltage Range VIN –0.3 to 6 V
Output Current IOUT 1 A
Output Voltage VOUT –0.3 to VBB + 1 V
Operating Ambient Temperature TAG temperature range –40 to 105 °C
Maximum Junction Temperature TJ(max) 150 °C
Storage Temperature Tstg –55 to 150 °C
Terminal List Table
Number Name Function
1 IN1 Logic input
2 IN2 Logic input
3 VBB Input supply
4 IN3 Logic input
5 IN4 Logic input
6 OUT4 Motor terminal
7 OUT3 Motor terminal
8 GND Ground
9 OUT2 Motor terminal
10 OUT1 Motor terminal
–PAD (LY package) Exposed thermal pad
Thermal Characteristics may require derating at maximum conditions, see application information
Characteristic Symbol Test Conditions* Value Unit
Package Thermal Resistance RθJA
LN package (estimated), on 1-layer PCB with copper limited
to pin area 130 °C/W
LY package, on 2-layer PCB with 2.260 in.2 of copper area
each side 48 °C/W
*Additional thermal information available on the Allegro website.
SELECTION GUIDE
Part Number Package Packing
A3909GLNx-T* 10-pin SSOP 3000 pieces per 13-in. reel
A3909GLYTR-T 10-pin MSOP with
exposed thermal pad 4000 pieces per 13-in. reel
*Contact Allegro Sales for availability of this package option.
IN1
IN2
VBB
IN3
IN4
OUT1
OUT2
GND
OUT3
OUT4
1
2
3
4
5
10
9
8
7
6
PAD
(LY
package)
LN and LY packages
Dual Full Bridge Motor Driver
A3909
3
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
ELECTRICAL CHARACTERISTICS*: Valid at TA = 25°C, unless otherwise specified
Characteristic Symbol Test Conditions Min. Typ. Max. Unit
VBB Voltage Range VBB 4 – 18 V
VBB Supply Current
IBB
– 4 8 mA
Standby Mode – <1 10 µA
Total Driver On-Resistance (Sink +
Source) RDS(on)tot
I = 1 A, TJ = 25°C, VBB = 12 V – 1.6 2 Ω
I = 1 A, TJ = 25°C, VBB = 4 V – 2.7 3.5 Ω
Source Driver On-Resistance RDS(on)src I = 1 A, TJ = 25°C, VBB = 12 V – 1.12 – Ω
Sink Driver On-Resistance RDS(on)snk I = 1 A, TJ = 25°C, VBB = 12 V – 0.48 – Ω
Input Logic Low Level VIL(Standby) All inputs low – – 0.4 V
Input Logic Low Level VIL – – 0.8 V
Input Logic High Level VIH 2 – – V
Input Hysteresis VHYS 100 300 500 mV
Logic Input Current IIN VIN = 5 V (Pull down = 50 kΩ) – 100 150 µA
VBB UVLO VBBUVLO VBB rising – 3.6 3.95 V
VBB UVLO Hysteresis VBBHYS 100 300 500 mV
Standby Timer tSTB IN1 = IN2 = IN3 = IN4 < VIL(Standby) – 1 1.5 ms
Thermal Shutdown Temperature TJTSD Temperature increasing 150 165 180 °C
Thermal Shutdown Hysteresis ΔTJ Recovery = TJTSD – ΔTJ – 20 – °C
*Specified limits are tested at a single temperature and assured through operating temperature range by design and characterization.
Dual Full Bridge Motor Driver
A3909
4
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Table 1: Motor Operation Truth Table
STEPPER MOTOR
IN1 IN2 IN3 IN4 OUT1 OUT2 OUT3 OUT4 Function
0000Off Off Off Off Sleep Mode Sleep Mode
1 0 1 0 H L H L Step 1 Step 1
0010Off Off H L – Step 2
0 1 1 0 L H H L Step 2 Step 3
0 1 0 0 L H Off Off – Step 4
0 1 0 1 L H L H Step 3 Step 5
0001Off Off L H – Step 6
1 0 0 1 H L L H Step 4 Step 7
1 0 0 0 H L Off Off – Step 8
DC MOTORS (DUAL)
IN1 or IN3 IN2 or IN4 OUT1 OUT2 OUT3 OUT4 Function
0 0 Off Off Off Off High Impedance
(Sleep Mode) / Coast
1 0 H L H L Forward
0 1 L H L H Reverse
11 L L L L Brake
DC MOTOR (SINGLE, PARALLELED)
IN1 or IN3 IN2 or IN4 OUT1 OUT2 OUT3 OUT4 Function
0 0 Off Off Off Off High Impedance
(Sleep Mode) / Coast
1 0 H L H L Forward
0 1 L H L H Reverse
1 1 L L L L Brake
DC MOTOR (EXTERNAL PWM)
IN1 or IN3 IN2 or IN4 OUT1 OUT2 OUT3 OUT4 Function
1 0 H L H L Forward
0 0 Off Off Off Off Fast Decay
0 1 L H L H Reverse
0 0 Off Off Off Off Fast Decay
1 0 H L H L Forward
1 1 L L L L Slow Decay
0 1 L H L H Reverse
1 1 L L L L Slow Decay
NOTE: 0 = logic low with VINx < VIN(0)(max), 1 = logic high with VINx > VIN(1)(min), H = voltage high, source driver on, L = voltage low, sink driver on
Dual Full Bridge Motor Driver
A3909
5
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
FUNCTIONAL DESCRIPTION
Device Operation
The 3909 is designed to operate two DC motors or a single
stepper motor. The outputs are PMOS source drivers combined
with low RDS(on) DMOS sink drivers.
Protection circuitry includes internal thermal shutdown, protec-
tionagainstshortedloads,andagainstoutputsshortedtoGND
or supply. Undervoltage lockout prevents damage by keeping the
outputs off until the driver has enough voltage to operate nor-
mally.
A low power standby (Sleep) mode is activated when all inputs
are low for longer than 1 ms. Sleep mode disables all of the cir-
cuitry making the IC ideal for battery operated applications.
Overcurrent Protection (OCP)
The A3909 is protected against accidental shorts or motor outputs
to ground and supply, as well as a shorted load condition. For
the source drivers, the current is monitored after the MOSFET is
turned on. If the current exceeds 1.8 A for longer than 2 µs, then
a fault condition is asserted. The sink driver utilizes a drain-to-
source voltage monitor. If the voltage exceeds 2 V for longer than
2 µs, the fault condition is asserted.
When a fault occurs, the IC immediately disables both sides of
the full bridge where the fault occurred. The full bridge input
commands will be ignored for a 2 ms period before being allowed
to retry. Each channel has independent overcurrent protection.
During OCP events, the absolute ratings may be exceeded for a
short period of time before the outputs are disabled.
Thermal Shutdown
If the die temperature increases to TJTSD , then all outputs are dis-
abled until the internal temperature falls below a hysteresis level,
TTSDHYS, of 20°C. Internal UVLO is detected on VBB to prevent
output drivers from turning on when below the UVLO threshold.
IN1
IN2
OUT1
OUT2
2 3 4
t
STANDBY
5 6 7
Current (12)
1) Low power standby (Sleep) mode (IBB = 0)
2) On, reverse – 100% duty cycle
3) On, forward – 100% duty cycle
4) Slow decay PWM
5) Fast decay PWM
6) Coast
7) Low power standby (Sleep) mode
after tSTANBY (IBB = 0)
DC Motor Timing Diagram
Dual Full Bridge Motor Driver
A3909
6
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Stepper Motor Timing Diagram
1
IN1
IN2
Current (12)
IN3
IN4
Current (34)
2
I
I
(2/4)
(1/3) (1/3)
I
(2/4)
3 41
2
3 4
1 2 3 4 5 6 7 8 1
12
5 7
3
4
6
8
Half Step Full Step
I
IN1
IN2
OUT1
OUT2
2 3 4
t
STANDBY
5 6 7
Current (12)
Dual Full Bridge Motor Driver
A3909
7
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
APPLICATION INFORMATION
Configuration for parallel operation with 1.8 A output current capability
Input Output Pin Structures
OUT4
OUT
A3909 1
OUT2
IN1
1
2
3
4
5
10
9
8
7
6
IN2
VBB
Load
System
Controller
Supply
DC Motor
IN3
PAD
(LY package)
IN4
GND
OUT3
GND
OUT1
OUT2
OUT3
OUT4
IN1
IN4
IN2
IN3
50 kΩ
V
BB
V
BB
21V
6.5 V
VBB
50 kΩ
21 V
LY package board via layout for thermal dissipationLN package board
Dual Full Bridge Motor Driver
A3909
8
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Package LN, 10-Pin SSOP
Terminal #1 mark area
A
1.55 ±0.20
1.00
BSC
21
10
A
C
C
0.21 ±0.04
1.05 (REF)
0.25
0.10
0° to 8°
4.90 ±0.20
3.90 ±0.10 6.00 ±0.20 4.95
2
1
10
0.65 1.00
2.25
0.45
0.30
1.27
0.40
For Reference Only; not for tooling use
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
Branded Face
PCB Layout Reference View
Reference land pattern layout. All pads a minimum of 0.20 mm from all
adjacent pads; adjust as necessary to meet application process
requirements and PCB layout tolerances; when mounting on a multilayer
PCB, thermal vias near the pin lands can improve thermal dissipation
(reference EIA/JEDEC Standard JESD51-7)
B
N = Device part number
= Supplier emblem
Y = Last two digits of year of manufacture
W = Week of manufacture
L = Lot number
NNNNNNN
LLLL
1
YYWW
Standard Branding Reference View
BBranding scale and appearance at supplier discretion
Dual Full Bridge Motor Driver
A3909
9
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
Package LY, 10-Pin MSOP
With Exposed Thermal Pad
Terminal #1 mark area
A
Gauge Plane
Seating Plane
0.86 ±0.05
SEATING
PLANE
0.50
REF
0.25
21
10
21
10
A
B
C
C
0.53 ±0.10
0.15 ±0.05
0.05
0.15
0° to 6°
3.00 ±0.10
3.00 ±0.10 4.88 ±0.20 1.73 4.60
1.98
1.98 MIN
1.73
21
10
1
0.30 0.50
1.65
0.27
0.18
For Reference Only; not for tooling use (reference JEDEC MO-187BA-T)
Dimensions in millimeters
Dimensions exclusive of mold flash, gate burrs, and dambar protrusions
Exact case and lead configuration at supplier discretion within limits shown
B
Exposed thermal pad (bottom surface)
Reference land pattern layout (reference IPC7351 SOP50P490X110-11M)
All pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary
to meet application process requirements and PCB layout tolerances; when
mounting on a multilayer PCB, thermal vias at the exposed thermal pad land
can improve thermal dissipation (reference EIA/JEDEC Standard JESD51-5)
Dual Full Bridge Motor Driver
A3909
10
Allegro MicroSystems, LLC
955 Perimeter Road
Manchester, NH 03103-3353 U.S.A.
www.allegromicro.com
For the latest version of this document, visit our website:
www.allegromicro.com
Revision History
Number Date Description
– November 15, 2018 Corrected Output Current units in Absolute Maximum Ratings table (page 2)
Copyright ©2018, Allegro MicroSystems, LLC
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permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that
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