SA9602H
TYPICAL APPLICATIONS
In the Application Circuits (Figures 1 and 2), the components required for power metering
applications, are shown.
In Figure 1 a shunt resistor is used for current sensing. In this application, the circuitry
requires a +2.5V, 0V, -2.5V DC supply.
In the case of Figure 2, when using a current transformer for current sensing, a +5V, 0V
DC supply is sufficient.
The most important external components for the SA9602H integrated circuit are:
R
2
, R
1
and RSH are the resistors defining the current level into the current sense input. The
values should be selected for an input current of 16µA
RMS
into the SA9602H at maximum
line current.
Values for RSH of less than 200µΩ should be avoided.
R
1
= R
2
= (I
L
/16µA)
RMS
* R
SH
/2
Where I
L
= Line current
RSH
= Shunt resistor/termination resistor
R
3
, R
6
and R
4
set the current for the voltage sense input. The values should be selected
so that the input current into the voltage sense input (virtual ground) is set to 14µA
RMS
.
R
7
defines all on-chip bias and reference currents. With R
7
= 24kΩ, optimum conditions
are set. R
7
may be varied within ±10% for calibration purposes. Any change to R
7
will affect
the output quadratically (i.e.: R
7
= +5%, f
P
= +10%).
The formula for calculating the output frequency is given below:
f = 11.16 * FOUTX *
Where FOUTX
FOSC
I
I
I
V
I
R
FOSC
3.58MHz
*
I
I
.I
V
I
R2
= Normal rated frequency (1160Hz)
= Oscillator frequency (2MHz ...... 4MHz)
= Input current for current input (16µA
RMS
at rated)
= Input current for voltage input (14µA
RMS
at rated)
= 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.
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