sa828 Mitel, sa828 Datasheet - Page 9

• Manufacturer Part Number: sa828
• Description: Three-phase Pwm Waveform Generator
• Manufacturer: Mitel

1. Setting the power frequency
accuracy (i.e 4096 equal steps) from 0Hz to f
in the initialisation register. In this case, with f
the power frequency can be adjusted in increments of 0·06Hz.
1638 this gives f
of this value gives a PFS word of 011001100110 in temporary
registers R0 and R1.
2. Setting overmodulation, forward/reverse, output inhibit
of the PWM outputs should be red-yellow-blue) therefore forward/
reverse bit F/R = 0.
active), therefore INH= 1.
3. Setting the power waveform amplitude
Control Register Programming Example
while the motor is running, but just one example is given here.
It is assumed that the initialisation register has already heen
programmed with the parameters given in the previous example.
waveform amplitude of 80% of that stored in the ROM. The
phase sequence should be set to give forward motor rotation.The
outputs should be enabled and no overmodulation is required.
of 11001100 in temporary register R2. The data which must be
programmed into the three temporary registers R0, R1 and R2
(for transfer into the control register) in order to achieve the
parameters in the example given, is shown in Fig. 16.
The power frequency, f
We can only have pfs as an integer, so if we assign pfs =
Overmodulation is not required therefore OM = 0.
Forward motor control is required (i.e., the phase sequence
Output inhibit should be inactive (i e., the outputs should be
These bits are all set in temporary register R1.
The control register would normally be updated many times
The 8-bit binary equivalent of this value gives an AMP word
A power waveform of 100Hz is required with a PWM
PFS
AMP
pfs =
F/R
1
0
0
7
7
PFS
AMP
A =
OM
f
POWER
1
1
0
f
POWER
POWER
6
6
f
A
RANGE
PFS
AMP
POWER
INH
Temporary Register R0
Temporary Register R1
Temporary Register R2
0
A
x 4096
1
1
POWER
= 99.97 Hz.The 12-bit binary equivalent
100
=
5
5
f
AMP
PFS
RANGE
4096
x 255
0
X
X
Fig. 16
0
POWER
=
=
4
4
225
PFS
x pfs
PFS
AMP
A
100 x 4096
=
1
, can be selected to 12-bit
0
0
x 100%
11
3
250
80 x 255
3
PFS
PFS
AMP
100
1
0
1
10
2
2
= 1638·4
PFS
RANGE
AMP
PFS
= 204
RANGE
0
1
1
9
1
1
PFS
PFS
AMP
as defined
= 250Hz,
0
1
0
8
0
0
BEFORE COMPLETING
REGISTER INHIBITING
WRITE TO CONTROL
Fig. 17 Typical SA828 programming routine
INITIALISATION
PWM OUTPUTS
RESET CYCLE
PWM OUTPUTS
CONTROL
WRITE
WRITE
DATA
ENABLE
DATA
NO
INITIALISATION
POWER ON
WRITE R2
WRITE R4
WRITE R2
WRITE R3
WRITE R2
WRITE R3
CONTROL
WRITE R0
WRITE R1
WRITE R0
WRITE R1
WRITE R0
WRITE R1
CHANGE
CHANGE
RST 1
RST 0
DATA ?
DATA ?
YES
NO
YES
SA828
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