ADVANCE INFORMATION
3896-1·0
MA828 FAMILY
THREE-PHASE PULSE WIDTH MODULATION WAVEFORM GENERATOR
The MA828 PWM generator has been designed to provide
waveforms for the control of variable speed AC machines,
uninterruptible power supplies and other forms of power elec-
tronic 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 MA828 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 MA828 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 periph-
eral, 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 functionally identical to the MA818 PWM
generator IC except that the waveform ROM is integrated on-
chip; in addition, the MA828 features three Zero Phase Pulse
(ZPP) outputs and a Waveform Sampling Synchronisation output
(WSS) for use as feedback in, for example, slip compensaton
systems. 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
MA828
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
MA828
22
21
20
19
18
17
16
15
MP28
Fig. 1 Pin connections – top view (not to scale)
FEATURES
s
Fully Digital Operation
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
MOTEL is a registered Trademark of Intel Corp. and Motorola Corp.
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
