115 Northeast Cutoff, Box 15036

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

3933

THREE-PHASE POWER

MOSFET CONTROLLER

FAULT — Open-drain output to indicate fault condition; will

go active high for any of the following:

1 – invalid HALL input code,

2 – high-side, gate-source voltage less than 7 V,

3 – bootstrap capacitor not sufficiently charged, or

4 – under-voltage condition detected at V

The fault state for gate-source and bootstrap monitors are

cleared at each commutation. If the motor has stalled, then the

fault can only be cleared by toggling the RESET terminal or

power-up sequence.

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

pulled up to V

HIGH), only the high-side FET is switched open during a PWM

OFF cycle. The fast-decay mode (logic LOW) switches both

the source and sink FETs.

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 logic

table. Internally pulled up to V

BRAKE — A logic input to short out the motor windings for a

braking function. A logic HIGH will turn ON the low-side

FETs, turn OFF the high-side FETs. Internally pulled up to

V

speed.

BRKCAP — Connection for reservoir capacitor. This terminal

is used to provide a positive power supply for the sink-drive

outputs for a power-down condition. This will allow predict-

quired. A 4.7

µF capacitor will provide 6.5 V gate drive for

300 ms. If a power-down braking option is not needed

(BRKSEL = LOW) then this terminal should be tied to V

BRKSEL — A logic input to enable/disable braking on power-

down condition. Internally pulled up to V

low, the motor will coast on a power-down condition.

PWM — Speed control input, internally pulled up to V

LCAP

(+5 V). A logic LOW turns OFF all drivers, a logic HIGH will

turn ON selected drivers as determined by H1/H2/H3 input

logic. Holding the terminal high allows speed/torque control

solely by the current-limit circuit via REF analog voltage

command.

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

external resistor (R

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

tions Information). As a rule, the fixed off time should not be

less than 10

µs. The resistor should be in the range of 10 kΩ to

100 k

Ω.

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 are ignored for time t

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

Voltage applied here sets the peak load current.

I

V

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. The terminal

V

connect a decoupling capacitor from this terminal to AGND, as

close to the device terminals as possible. This terminal should

be shorted to V

LCAP — Connection for decoupling capacitor for the internal

5 V reference. This terminal can source no more than 2 mA.

DEAD — An analog input. A resistor between DEAD and

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

is needed to prevent shoot-through in the external power FETs.

The allowable resistor range is 20 k

Ω to 430 kΩ, which

converts to deadtime of 210 ns to 2.1

µs, using the following

equation:

t

AGND — The low-level (analog) reference point for the

A3933.

PGND — The reference point for all low-side gate drivers.

Terminal Descriptions (cont’d)