UCC2626

UCC3626

PRELIMINARY

04/99

FEATURES

• Two Quadrant and Four Quadrant

Operation

• Integrated Absolute Value Current

Amplifier

• Pulse-by-Pulse and Average Current

Sensing

• Accurate, Variable Duty Cycle

Tachometer Output

• Trimmed Precision Reference

• Precision Oscillator

• Direction Output

Brushless DC Motor Controller

17

HALLC

8

DIR_OUT

14

PWM_NI

13

PWM_I

16

HALLB

SYNCH

11

OC_REF

9

SNS_I

3

4

1

5

22

CLOW

C_TACH

R_TACH

TACH_OUT

GND

2VREF

27

AHI

25

BHI

23

CHI

26

ALOW

10

SNS_NI

IOUT

7

6

12

CT

18

COAST

21

DIR_IN

15

HALLA

19

BRAKE

20

QUAD

SENSE AMPLIFIER

OVER-CURRENT

COMPARATOR

OSCILLATOR

DIRECTION

DETECTOR

EDGE

DETECTOR

28

VDD

ONE SHOT

R•C

5VOLT

REFERENCE

Q

Q

S

R

PWM LOGIC

24

BLOW

1.75V

DIRECTION

SELECT

HALL

DECODER

PWM COMPARATOR

X5

Q

Q

S

R

BLOCK DIAGRAM

UDG-97173

DESCRIPTION

The UCC3626 motor controller IC combines many of the functions re-

quired to design a high performance, two or four quadrant, 3-phase,

brushless DC motor controller into one package. Rotor position inputs

are decoded to provide six outputs that control an external power stage.

A precision triangle oscillator and latched comparator provide PWM mo-

tor control in either voltage or current mode configurations. The oscilla-

tor is easily synchronized to an external master clock source via the

SYNCH input. Additionally, a QUAD select input configures the chip to

modulate either the low side switches only, or both upper and lower

switches, allowing the user to minimize switching losses in less de-

manding two quadrant applications.

The chip includes a differential current sense amplifier and absolute

value circuit which provide an accurate reconstruction of motor current,

useful for pulse by pulse over current protection as well as closing a

current control loop. A precision tachometer is also provided for imple-

menting closed loop speed control. The TACH_OUT signal is a variable

duty cycle, frequency output which can be used directly for digital con-

trol or filtered to provide an analog feedback signal. Other features in-

clude COAST, BRAKE, and DIR_IN commands along with a direction

output, DIR_OUT.

application

INFO

available