SA828 Family
Three-Phase PWM Waveform Generator
DS4226 - 2.0 November 1996
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
MOTEL
TM
bus, compatible with most microprocessors/controllers.
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.
AD
3
AD
4
AD
5
AD
6
AD
7
WR* (R/W†)
RD* (DS†)
ALE* (AS†)
RST
CLK
CS
TRIP
RPHB
YPHB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
AD
2
AD
1
AD
0
VDD
ZPPB
ZPPY
ZPPR
WSS
RPHT
SET TRIP
YPHT
BPHT
V
SS
BPHB
SA828
21
20
19
18
17
16
15
DP28
*
= Intel bus format
† = Motorola bus format
AD
3
AD
4
AD
5
AD
6
AD
7
WR* (R/W†)
RD* (DS†)
ALE* (AS†)
RST
CLK
CS
TRIP
RPHB
YPHB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
AD
2
AD
1
AD
0
VDD
ZPPB
ZPPY
ZPPR
WSS
RPHT
SET TRIP
YPHT
BPHT
V
SS
BPHB
SA828
22
21
20
19
18
17
16
15
MP28
FEATURES
s
Fully Digital Operation
Fig. 1 Pin connections – top view (not to scale)
s
Interfaces with Most Microprocessors
s
Wide Power-Frequency Range
s
12-Bit Speed Control Accuracy
s
Carrier Frequency Selectable up to 24kHz
s
Waveform Stored in Internal ROM
s
Double Edged Regular Sampling
s
Selectable Minimum Pulse Width and Underlap Time
s
DC Injection Braking
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)
MOTEL is a registered Trademark of Intel Corp. and Motorola Corp.
MITEL [ MITEL NETWORKS CORPORATION ]
