A3938 Datasheet, PDF (1/11 Pages) Allegro MicroSystems – Three-Phase Power MOSFET Controller

A3938
Three-Phase Power MOSFET Controller
Features and Benefits
▪ Drives a wide range of N-channel MOSFETs
▪ Low-side synchronous rectification
▪ Power MOSFET protection
▪ Adjustable dead time for cross-conduction protection
▪ Selectable coast or dynamic brake on power-down or
RESET input
▪ Fast/slow current decay modes
▪ Internal PWM current control
▪ Motor lead short-to-ground protection
▪ Internal 5 V regulator
▪ Fault diagnostic output
▪ Thermal shutdown
▪ Undervoltage protection
Package 38-pin TSSOP (suffix LD):
Approximate Scale 1:1
Description
The A3938 is a three-phase, brushless DC motor controller.
It has a high-current gate drive capability that 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 external 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 voltage 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 during 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 H-all 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 lead (Pb) free, with 100% matte tin plated
leadframe.
26301.104H
RESET 1
GLC 2
SC 3
N/C 4
N/C 5
GHC 6
CC 7
GLB 8
SB 9
GHB 10
CB 11
GLA 12
SA 13
GHA 14
CA 15
VREG 16
LCAP 17
N/C 18
FAULT 19
38 N/C
37 N/C
36 PGND
35 AGND
34 DEAD
33 REF
32 SENSE
31 RC
30 PWM
29 BRKSEL
Control ^{28 BRKCAP}
Fault
Logic
27 BRAKE
26 DIR
25 H2
24 H3
23 N/C
22 H1
21 VBB
20 MODE