Description
The A4937 is a 3-phase controller for use with N-channel
external power MOSFETs and is specifically designed for
automotive applications.
A unique charge pump regulator provides full (>10 V) gate
drive for battery voltages down to 7 V and allows the A4937
to operate with a reduced gate drive, down to 5.5 V.
A bootstrap capacitor is used to provide the above battery
supply voltage required for N-channel MOSFETs.
Full control over all six power MOSFETs in the 3-phase bridge
is provided, through an SPI compatible serial interface, allowing
motors to be driven with block or overlap commutation. Power
output can be regulated by one or both of the PWM inputs.
The power MOSFETs are protected from shoot-through by
integrated crossover control and programmable dead time.
Integrated diagnostics provide indication of undervoltage,
overtemperature, and power bridge faults, and can be configured
to protect the power MOSFETs under most short circuit
conditions. Detailed diagnostics are available as a serial data
word.
The A4937 is supplied in a 28-pin TSSOP power package with
with exposed pad for enhanced thermal dissipation (package
type LP). This package is lead (Pb) free, with 100% matte-tin
leadframe plating.
A4937A-DS
Features and Benefits
• High current 3-phase gate drive for N-channel MOSFETs
• SPI compatible serial control
• Cross-conduction protection
• Programmable dead time
• 5.5 to 50 V supply voltage range
• TTL inputs compatible with 3.3 V and 5 V logic
• Extensive diagnostics output
• Low current sleep mode
Applications
Automotive 3-Phase MOSFET Driver
Package: 28-pin TSSOP with Exposed
Thermal Pad (suffix LP)
Functional Block Diagram
Not to scale
A4937
3-Phase
BLDC
Motor
A4937
VBAT
SPI
A8450
Regulator
Micro-
controller
VBAT
PWM
Reset
Diagnostics
• Electronic power steering (EPS, EHPS, EAS)
• Hydraulic pumps
• Gearbox actuator
Automotive 3-Phase MOSFET Driver
A4937
2
Allegro MicroSystems, LLC
115 Northeast Cutoff
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Absolute Maximum Ratings*
Characteristic Symbol Notes Rating Unit
Load Supply Voltage VBB –0.3 to 50 V
Logic Supply Voltage VDD –0.3 to 6 V
Terminal VREG VREG –0.3 to 16 V
Terminal CP1 VCP1 –0.3 to 16 V
Terminal CP2 VCP2
VCP1 – 0.3 to
VREG + 0.3 V
Logic Inputs VI
STRn, SCK, SDI, PWMH, PWML –0.3 to 6 V
RESETn; can be pulled to VBB with >22 kΩ–0.3 to 6 V
Logic Outputs VOSDO –0.3 to VDD + 0.3 V
Terminal DIAG VDIAG –0.3 to VDD + 0.3 V
Terminal VBRG VBRG –5 to 55 V
Terminals CA, CB, CC VCx –0.3 to VREG + 50 V
Terminals GHA, GHB, GHC VGHx
VCx – 16 to
VCx + 0.3 V
Terminals SA, SB, SC VSx
VCx – 16 to
VCx + 0.3 V
Terminals GLA, GLB, GLC VGLx VREG – 16 to 18 V
Terminal LSS VLSS VREG – 16 to 18 V
Ambient Operating Temperature
Range TALimited by power dissipation –40 to 150 °C
Maximum Continuous Junction
Temperature TJ(max) 150 °C
Transient Junction Temperature TtJ
Overtemperature event not exceeding 10s,
lifetime duration not exceeding 10 hours,
guaranteed by design characterization.
175 °C
Storage Temperature Range Tstg –55 to 150 °C
*With respect to GND. Ratings apply when no other circuit operating constraints are present.
Thermal Characteristics may require derating at maximum conditions
Characteristic Symbol Test Conditions* Value Unit
Package Thermal Resistance (Junction
to Ambient) RθJA
On 4-layer PCB based on JEDEC standard 28 ºC/W
2-layer PCB with 3.8 in.2 of copper area
each side 32 ºC/W
Package Thermal Resistance (Junction
to Pad) RθJP 2 ºC/W
*Additional thermal information available on the Allegro website.
Selection Guide
Part Number Packing* Package
A4937KLPTR-A-T 4000 pieces per 13-in. reel 4.4 mm × 9.7 mm, 1.2 mm maximum height TSSOP
with exposed thermal pad
*Contact Allegro™ for additional packing options.
Automotive 3-Phase MOSFET Driver
A4937
Worcester, Massachusetts 01615-0036 U.S.A.
1.508.853.5000; www.allegromicro.com
Functional Block Diagram
Charge
Pump
Regulator
VBAT
CP2CP1
DIAG
LSS
GLA
GHA
SA
CA
VREG
Battery +
VREG
Phase A
VBB
PWML
Phase C
Phase B
CBOOTA
CREG
CP
PWMH
VBRG
Bootstrap
Monitor
VDS
Monitor
VDS
Monitor
GND
STRn
SCK
SDI
SDO
VDD
Control
Logic
Diagnostics
and
Protection
Serial
Interface
RESETn
One of three phases shown
RGATE
RGATE
High Side
Drive
Low Side
Drive
Allegro MicroSystems, LLC 3
115 Northeast Cutoff
