SA9122E
4. Electrostatic Discharge (ESD) Protection
TheSA9122Eintegratedcircuit'sinputs/outputsareprotectedagainstESDaccording
to Mil-Std 883C, method 3015.
5. Power Consumption
ThepowerconsumptionratingoftheSA9122Eintegratedcircuitislessthan25mW.
TYPICAL APPLICATIONS
In the Application Circuit (Figure 1), the components required for this power metering
application, 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.
The most important external components for the SA9122E integrated circuit are:
C1 and C2 are the outer loop capacitors for the two integrated oversampling A/D
converters. The value of these capacitors is 560pF.
Theactualvaluesdeterminethesignaltonoiseandstabilityperformance. Thetolerances
should be within ±10%.
C3 and C4 are the inner loop capacitors of the A/D converters. The optimum value is
3.3nF. The actual values are uncritical. Values smaller than 0.5nF and larger than 5nF
should be avoided.
R2, R1 and RSH are the resistors defining the current level into the current sense input.
The values should be selected for an input current of 16µARMS into the SA9122E 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 the reference current (IR). With R7 = 24kΩ, optimum conditions are set. R7
may be varied within ±10% for calibration purposes. Any change to R7 will affect the
output quadratically (i.e.: R7 = +5%, fP = +10%).
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