A3938

Three-Phase Power MOSFET Controller

The A3938 is a three-phase, brushless dc motor controller. The A3938

high-current gate drive capability allows driving of a wide range of

power MOSFETs and can support motor supply voltages to 50 V. The

A3938 integrates a bootstrapped high-side driver to minimize the exter-

nal component count required to drive N-channel MOSFET drivers.

Internal fixed off-time, PWM current-control circuitry can be used to

regulate the maximum load current to a desired value. The peak load

current limit is set by the user’s selection of an input reference volt-

age and external sensing resistor. A user-selected external RC timing

network sets the fixed off-time pulse duration. For added flexibility, the

PWM input can provide speed/torque control where the internal current

control circuit sets a limit on the maximum current.

The A3938 includes a synchronous rectification feature. This shorts out

the current path through the power MOSFET reverse body diodes dur-

ing PWM off-cycle current decay. This can minimize power dissipation

in the MOSFETs, eliminate the need for external power clamp diodes,

and potentially allow a more economical choice for the MOSFET drivers.

The A3938 provides commutation logic for Hall sensors configured for

120-degree spacing. The Hall input pins are pulled-up to an internally-

generated 5 V reference. Power MOSFET protection features include:

bootstrap capacitor charging current monitor, regulator undervoltage

monitor, motor lead short-to-ground, and thermal shutdown.

The LD package is available in a lead-free version (100% matte tin

plated leadframe).

Drives wide range of N-channel MOSFETs

Low-side synchronous rectification

Power MOSFET protection

Adjustable dead time for cross-con-

duction protection

Selectable coast or dynamic brake on

power-down or RESET input

Fast/slow current decay modes

Use the following complete part numbers when ordering:

ABSOLUTE MAXIMUM RATINGS

Part Number

Pins

Package

A3938SEQ

32

PLCC

A3938SLQ

36

QSOP

A3938SLD

38

TSSOP

A3938SLD-T

38

TSSOP, Lead-free

Load Supply Voltage, V

VREG (Transient) ...............................................15 V

Logic Input Voltage Range,V

Sense Voltage, V

Pins: SA, SB, SC................................... –5 V to 50 V

Pins: GHA, GHB, GHC.................. –5VtoV

Pins: CA, CB, CC ...........................SA/SB/SC + 17V

Operating Temperature Range

Ambient Temperature, T

Junction Temperature, T

Storage Temperature, T

Thermal Impedance (Typical), at T

measured on a JEDEC-standard "High-K" PCB

A3938EQ, R

A3938LD, R

A3938LQ, R

FEATURES

Internal PWM current control

Motor lead short-to-ground

protection

Internal 5 V regulator

Fault diagnostic output

Thermal shutdown

Undervoltage protection

A3938LD, 38-pin TSSOP

A3938EQ, 32-pin PLCC

A3938LQ, 36-pin QSOP