115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000

3932

THREE-PHASE POWER

MOSFET CONTROLLER

6

FAULT — Open-drain output to indicate fault condition;

FAULT = 1 (external pull-up) for any of the following:

1 – invalid HALL input code,

2 – undervoltage condition detected at VREG.

3 – thermal shutdown, or

4 – motor lead (SA/SB/SC) shorted to ground.

Except for a short-to-ground fault that only turns off the

high-side drivers, faults will force a coast condition that turns

off all power MOSFETs. Only the short-to-ground fault is

latched but is cleared at each commutation. If the motor has

stalled due to a short-to-ground being detected, toggling the

RESET terminal or repeating a power-up sequence will clear

the fault. Typically pulled up to V

5.1 k

Ω resistor.

MODE — A logic input to set current-decay method, internally

pulled up to V

= 1), only the high-side MOSFET is switched off during a

PWM-off cycle. The fast-decay mode (MODE = 0) switches

both the high-side and low-side MOSFETs.

H1/H2/H3 — Hall-sensor inputs; internally pulled up to V

LCAP

(+5 V). Configured for 120

° electrical spacing.

DIR — A logic input to reverse rotation, see Commutation

Truth Table. Internally pulled up to V

BRAKE — An active-low logic input for a braking function. A

BRAKE = 0 will turn on the low-side FETs and turn off the

high-side FETs. This will effectively short-circuit the BEMF in

the windings and brake the motor. The braking torque applied

will depend on the speed. Internally pulled up to V

RESET = 1 overrides BRAKE and will coast the motor.

SR — Synchronous rectification input. An SR = 0 disables this

feature, forcing current decay through the body diodes of the

power MOSFETs. An SR = 1 will result in appropriate high-

and low-side gate outputs to switch in response to a PWM-off

command. Internally pulled up to V

Input Logic table.

TACH — An open-drain digital output whose frequency is

proportional to speed of rotation. A pulse appears at every

HALL transition. Typically pulled up to V

external 5.1 k

Ω resistor.

PWM — Speed control input, internally pulled up to V

LCAP

(+5 V). A PWM = 0 turns off selected drivers. A PWM = 1

will turn on selected drivers as determined by H1/H2/H3 input

logic. Holding PWM = 1 allows speed/torque control solely by

the internal current-limit circuit with the REF analog voltage.

See also the Input Logic table

.

RC — An analog input used to set the fixed off time with an

controlled by the value of the external capacitor (see Applica-

tions Information). See Application Information.

SENSE — An analog input to the current-limit comparator.

A voltage representing load current appears on this terminal

during on time, when it reaches REF voltage, the comparator

trips and load current decays for the fixed off-time interval.

Voltage transients seen at this terminal when the drivers turn on

REF — An analog input to the current-limit comparator.

Voltage applied here with respect to AGND sets the peak load

current.

VREG — A regulated 13 V output; supply for low-side gate

drive and bootstrap capacitor charge circuits. It is good practice

to connect a decoupling capacitor from this terminal to AGND,

as close to the device terminals as possible. This terminal

VBB — The A3932 supply voltage. It is good practice to

connect a decoupling capacitor from this terminal to AGND, as

close to the device terminals as possible.

LCAP — Connection for 0.1

µF decoupling capacitor for the

internal 5 V reference. This terminal can source no more than

3 mA for the DEAD input, TACH and FAULT outputs.

DEAD — An analog input. A resistor between DEAD and

LCAP is selected to adjust the turn-off to turn-on time. This

delay is needed to prevent shoot-through in the external power

MOSFETs. See Applications Information for details on setting

dead time.

AGND — The low-level (analog) reference point.

PGND — The return for all low-side gate drivers.

This should

be connected to the system power ground.

Terminal Descriptions (cont’d)