SA9603B
ssaammeess
TYPICAL APPLICATION
Values for RSH of less than 200µW should be avoided.
R = R = (I /16µA ) * RSH/2
In the Application Circuits (Figure 6 and 7), the components
required for power metering application are shown.
1
2
L
RMS
Where:
I = Line current
L
In Figure 6 a shunt resistor is used for current sensing. In this
application, the circuitry requires a +2.5V, 0V, -2.5V DC supply.
RSH = Shunt resistor / termination resistor
R , R and R set the current for the voltage sense input. The
4
3
6
In the case of Figure 7, when using a current transformer for
current sensing, a +5V, 0V DC supply is sufficient for the circuit.
values should be selected so that the input current into the
voltage sense input (virtual ground) is set to 14µA . R
RMS
7
defines all on-chip bias and reference currents. With R =
7
Two current sense input require a differential approach to cater
for precisions across the dynamic range. It is, therefore,
important that the PC board layout for the branches to the
sensing elements are as symmetrical as possible and the loop
area kept to a minimum.
24kW, optimum conditions area set.
R defines all on-chip bias and reference currents. With R =
7
7
24kW, optimum conditions area set. R may be varied by up to ±
7
10% for calibration purposes. Any changes to R will affect the
7
output quadratically (i.e.:ÎR = +5%, thenÎP = +10%).
The most important external components for the SA9603B
integrated circuit are:
XTAL is a colour burst TV crystal (f = 3.5795MHz) for the
oscillator. The oscillator frequency is divided down to
1.7897MHz on-chip to supply the A/D Converters and digital
circuitry.
R , R and RSH are the resistors defining the current level into
1
2
the current sense input. The values should be selected for an
input current of 16µA into the SA9603B at rated line current.
RMS
8/12
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