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
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
Three-Phase Power MOSFET Controller
Package 38-pin TSSOP (suffix LD):
A3938
Approximate Scale 1:1
Fault
7
8
9
10
11
12
13
6
5
30
29
28
27
26
25
24
31
32
15
16
17
18
14
1
2
3
4
22
21
20
19
23
36
35
38
37
34
33
SENSE
RC
PWM
BRKSEL
BRKCAP
BRAKE
DIR
H2
H3
N/C
GHC
CC
GLB
SB
GHB
CB
GLA
SA
GHA
CA
VREG
LCAP
N/C
FAULT
RESET
GLC
SC
N/C
PGND
AGND
DEAD
REF
N/C
H1
VBB
MODE
N/C
N/C
Control
Logic
