The SA828 PWM generator has been designed to provide

waveforms for the control of variable speed AC machines,

uninterruptible power supplies and other forms of power

electronic devices which require pulse width modulation as a

means of efficient power control.

The six TTL level PWM outputs (Fig. 2) control the six

switches in a three-phase inverter bridge. This is usually via an

external isolation and amplification stage.

The SA828 is fabricated in CMOS for low power

consumption.

Information contained within the pulse width modulated

sequences controls the shape, power frequency, amplitude,

and rotational direction (as defined by the red-yellow-blue

phase sequence) of the output waveform. Parameters such as

the carrier frequency, minimum pulse width, and pulse delay

time may be defined during the initialisation of the device. The

pulse delay time (underlap) controls the delay between turning

on and off the two power switches in each output phase of the

inverter bridge, in order to accommodate variations in the turn-

on and turn-off times of families of power devices.

The SA828 is easily controlled by a microprocessor and its

fully-digital generation of PWM waveforms gives unprecedented

accuracy and temperature stability. Precision pulse shaping

capability allows optimum efficiency with any power circuitry.

The device operates as a stand-alone microprocessor

peripheral, reading the power waveform directly from an

internal ROM and requiring microprocessor intervention only

when operating parameters need to be changed.

An 8-bit multiplexed data bus is used to receive addresses and

data from the microprocessor/controller. This is a standard

Rotational frequency is defined to 12 bits for high accuracy

and a zero setting is included in order to implement DC

injection braking with no software overhead.

This family is pin and functionally compatible with the

MA828 PWM generator . Two standard wave shapes are

available to cover most applications. In addition, any

symmetrical wave shape can be integrated on-chip to order.

FEATURES

DP28

MP28

Fig. 1 Pin connections – top view (not to scale)

MOTEL is a registered Trademark of Intel Corp. and Motorola Corp.

VDD

ZPPB

ZPPY

ZPPR

WSS

RPHT

SET TRIP

YPHT

BPHT

BPHB

WR* (R/W†)

RD* (DS†)

ALE* (AS†)

RST

CLK

CS

TRIP

RPHB

YPHB

† = Motorola bus format

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

SA828

SA828

1

2

3

4

5

6

7

8

9

10

11

12

13

14

28

27

26

25

24

23

22

21

20

19

18

17

16

15

VDD

ZPPB

ZPPY

ZPPR

WSS

RPHT

SET TRIP

YPHT

BPHT

BPHB

WR* (R/W†)

RD* (DS†)

ALE* (AS†)

RST

CLK

CS

TRIP

RPHB

YPHB

ORDERING INFORMATION

SA8281/IG/DP1S (28-lead DIL, sine + third harmonic

waveform)

SA8282/IG/DP1S (28-lead DIL, sine waveform)

SA8281/IG/MP1S (28-lead SOIC, Sine + third

harmonic waveform)

SA8382/IG/MP1S (28-lead SOIC, sine waveform)

SA828 Family

Three-Phase PWM Waveform Generator

DS4226 - 2.0 November 1996