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
fi
xed 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
fi
xed off-time pulse duration. For added
fl
exibility, 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).
ABSOLUTE MAXIMUM RATINGS
Load Supply Voltage, V
BB
...................................50
V
VREG (Transient) ...............................................15
V
Logic Input Voltage Range, V
IN
...–0.3
V to V
LCAP
+0.3 V
Sense Voltage, V
SENSE
...........................
–5 V to 1.5 V
Pins: SA, SB, SC...................................
–5 V to 50 V
Pins: GHA, GHB, GHC ..................
–5 V to V
BB
+ 17 V
Pins: CA, CB, CC ...........................SA/SB/SC
+ 17 V
Operating Temperature Range
Ambient Temperature, T
A
.............–20°C
to +85°C
Junction Temperature, T
J
............................+150°C
Storage Temperature, T
S
..........–55°C
to +150°C
Thermal Impedance (Typical), at T
A
= +25ºC;
measured on a JEDEC-standard "High-K" PCB
A3938EQ, R
θJA
........................................37°C/W
A3938LD, R
θJA
........................................38°C/W
A3938LQ, R
θJA
........................................44°C/W
26301.104B
Data Sheet
A3938EQ, 32-pin PLCC
A3938LQ, 36-pin QSOP
A3938LD, 38-pin TSSOP
FEATURES
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
Internal PWM current control
Motor lead short-to-ground
protection
Internal 5 V regulator
Fault diagnostic output
Thermal shutdown
Undervoltage protection
Use the following complete part numbers when ordering:
Part Number
A3938SEQ
A3938SLQ
A3938SLD
A3938SLD-T
Pins
32
36
38
38
Package
PLCC
QSOP
TSSOP
TSSOP, Lead-free
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