SA9105E
The formula for calculating the Output Frequency (f) is given below:
FOSC
3.58MHz
(II1 IV1) + (II2 IV2) + (I IV3)
I3
f = 11.16
FOUTX
*
*
*
2
3 I
*
R
Where FOUTX = Nominal rated frequency (4Hz, 290Hz or 1160Hz)
FOSC = Oscillator frequency (2MHz ...... 4MHz)
II1, II2, II3 = Input currents for current inputs (16µA at rated)
IV1, IV2, IV3 = Input currents for voltage inputs (14µA at rated)
IR
= Reference current (typically 50µA)
XTAL is a colour burst TV crystal (f = 3.5795 MHz) for the oscillator. The oscillator
frequency is divided down to 1.7897 MHz on-chip, to supply the digital circuitry and the
A/D converters.
Figure 1: Application Circuit for Three Phase Power/Energy Measurement.
MAINS VOLTAGES
R 1
R 2
R 1 A
R 2 A
LINE 1
LINE 2
R 3
R 3 A
LINE 3
C 4
N
5V
40
1
0V
2
39
38
C 5
C 6
C 9
3
4
5
6
R 7
37
36
35
34
FROM CTs
C 1 0
R 1 8
R 1 9
R 2 0
R 8
VI1P
VI1N
VI2P
VI2N
VI3P
R 1 5
C 1
C 2
C 3
R 9
+
+
+
7
SA9105A
DIP-40
IC-1
R 1 6
R 1 7
R 1 0
R 1 1
R 1 2
R 1 3
2.5V
8
9
33
32
R 6
P 6
R 5
P 5
R 4
R 2 1
10
11
12
13
31
30
29
28
C 1 4
C 1 1
VI3N
C 7
2.5V
2.5V
5 V
14
15
27
26
25
24
23
22
C 8
C 1 3
0V
16
17
18
19
FOUT3
FOUT2
0V
0V
0V
FOUT1
0V
20
21
XTAL
C 1 2
DR-00233
R14
P14
0V
44/12
sames
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