A3935 Allegro MicroSystems, Inc., A3935 Datasheet - Page 9

• Manufacturer Part Number: A3935
• Description: Three-Phase Power MOSFET Controller
• Manufacturer: Allegro MicroSystems, Inc.

AHI/BHI/CHI. Direct control of high-side gate outputs GHA/
GHB/GHC. Logic “1” drives the gate “on”. Logic ”0” pulls the
gate down, turning off the external power MOSFET. Internally
pulled down when terminal is open.
ALO/BLO/CLO. Direct control of low-side gate outputs GLA/
GLB/GLC. Logic “1” drives the gate “on”. Logic ”0” pulls the
gate down, turning off the external power MOSFET. Internally
pulled down when terminal is open.
BOOSTD. Boost converter switch drain connection.
BOOSTS. Boost converter switch source connection.
CA/CB/CC. High-side connection for bootstrap capacitor,
positive supply for high-side gate drive. The bootstrap capacitor
is charged to VREG when the output Sx terminal is low. When
the output swings high, the voltage on this terminal rises with
the output to provide the boosted gate voltage needed for n-
channel power MOSFETs.
CSN. Input for current-sense, differential amplifier, inverting,
negative side. Kelvin connection for ground side of current-
sense resistor.
CSOUT. Amplifier output voltage proportional to current
sensed across an external low-value resistor placed in the
ground-side of the power FET bridge.
CSP. Input for current-sense differential amplifier, non-
inverting, positive side. Connected to positive side of sense
resistor.
ENABLE. Logic “0” disables the gate control signals and
switches off all the gate drivers “low” causing a “coast”. Can be
used in conjunction with the gate inputs to PWM the load
current. Internally pulled down when terminal is open.
FAULT. Diagnostic logic output signal, when “low” indicates
that one or more fault condition have occurred.
GHA/GHB/GHC. High-side gate-drive outputs for n-channel
MOSFET drivers. External series gate resistors can control slew
rate seen at the power driver gate; thereby, controlling the di/dt
and dv/dt of Sx outputs.
GLA/GLB/GLC. Low-side gate drive outputs for external, n-
channel MOSFET drivers. External series gate resistors can
control slew rate.
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Terminal Descriptions
GND. Ground or negative side of VDD and VBAT supplies.
LSS. Low-side gate driver returns. Connects to the common
sources in the low-side of the power MOSFET bridge.
OVFLT. Logic “1” means that the VBAT exceeded the VBAT
overvoltage trip point set by OVSET level. It will recover after
a hysteresis below that maximum value. Normally has a high-
impedance state.
OVSET. A positive, dc level that controls the VBAT overvolt-
age trip point. Usually, provided from precision resistor divider
network between V
preset value. When terminal is open, sets unspecified but high
overvoltage trip point.
SA/SB/SC. Directly connected to the motor terminals, these
terminals sense the voltages switched across the load and are
connected to the negative side of the bootstrap capacitors. Also,
are the negative supply connection for the floating, high-side
drivers.
UVFLT. Logic “1” means that VBAT is below its minimum
value and will recover after a hysteresis above that minimum
value. Has a high-impedance state. [If UVFLT and OVFLT are
both in high-impedance state; then, at least, a thermal shutdown
or VDD undervoltage has occurred.]
VBAT. Battery voltage, positive input and is usually connected
to the motor voltage supply.
VBOOST. Boost converter output, nominally 16 V, is also
input to regulator for VREG. Has internal boost current and
boost voltage control loops. In high-voltage systems is approxi-
mately one diode drop below V
VDD. Logic supply, nominally +5 V.
VDRAIN. Kelvin connection for drain-to-source voltage
monitor and is connected to high-side drains of MOSFET
bridge. High impedance when terminal is open and registers as
a short-to-ground fault on all motor phases.
VDSTH. A positive, dc level that sets the drain-to-source
monitor threshold voltage. Internally pulled down when
terminal is open.
VREG. High-side, gate-driver supply, nominally, 13.5 V. Has
low-voltage dropout (LDO) feature.
MOSFET CONTROLLER
THREE-PHASE POWER
DD
and GND, but can be held grounded for a
BAT
.
3935
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