SA9602F/SA9602J
TYPICAL APPLICATIONS
In the Application Circuits (Figures 1 and 2), the components required forpower 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 SA9602F and SA9602J integrated
circuits are:
R2,R1 andRSHaretheresistorsdefiningthecurrentlevelintothecurrentsenseinput. The
valuesshouldbeselectedforaninputcurrentof16µARMS intotheSA9602FandSA9602J,
at maximum line current.
Values for RSH of less than 200µΩ should be avoided.
R1 = R2 = (IL/16µARMS )* RSH/2
Where IL
RSH
=
=
Line current
Shunt resistor/termination resistor
R3, R6 and R4 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 14µARMS
.
R7 defines all on-chip bias and reference currents. With R7 = 24kΩ, optimum conditions
areset. R7maybevariedwithin±10%forcalibrationpurposes. AnychangetoR7willaffect
the output quadratically (i.e.: R7 = +5%, fP = +10%).
The formula for calculating the output frequency is given below:
FOSC
I .IV
I
f = 11.16
FOUTX
*
*
*
2
3.58MHz
IR
Where FOUTX = Normal rated frequency (64Hz)
FOSC
= Oscillator frequency (2MHz ...... 4MHz)
II
= Input current for current input (16µARMS at rated)
= Input current for voltage input (14µARMS at rated)
IV
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.
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