8905

3-PHASE BRUSHLESS DC

MOTOR CONTROLLER/DRIVER

TERMINAL FUNCTIONS

Term.

Terminal Name

Function

1

LOAD SUPPLY

One of two capacitors used to generate the ideal commutation points from the back-EMF

zero-crossing points.

Timing capacitor used by the watchdog circuit to disable the back-EMF comparators

during commutation transients, and to detect incorrect motor position.

Startup oscillator timing capacitor.

5

Power amplifier output A to motor.

6-7

GROUND

Power and logic ground and thermal heat sink.

8

Power amplifier output B to motor.

9

Power amplifier output C to motor.

10

CENTERTAP

Motor centertap connection for back-EMF detection circuitry.

11

BRAKE

Active low turns ON all three sink drivers shorting the motor windings to ground. External

controlled via the serial port.

12

External reservoir capacitor used to hold charge to drive the source drivers’ gates. Also

provides power for brake circuit.

13

FILTER

Analog voltage input to control motor current. Also, compensation node for internal speed

control loop.

14

INDEX

External tachometer input.

15

LOGIC SUPPLY

16

OSCILLATOR

Clock input for the speed reference counter. Typical max. frequency is 10 MHz.

17

DATA OUT

Thermal shutdown indicator, FCOM, TACH, or SYNC signals available in real time,

controlled by 2-bit multiplexer in serial port.

18-19

GROUND

Power and logic ground and thermal heat sink.

20

RESET

When pulled low forces the chip into sleep mode; clears all serial port bits.

21

CHIP SELECT

Strobe input (active low) for data word.

22

CLOCK

Clock input for serial port.

23

DATA IN

Sequential data input for the serial port.

24

One of two capacitors used to generate the ideal commutation points from the back-EMF

zero-crossing points.