PM9106APA Datasheet, PDF (5/10 Pages) Sames – SINGLE PHASE WATT MEASUREMENT MODULE WITH A 5 DIGIT LED DISPLAY

PM9106AP
The most important external components for the SA9106AP device are:
C₁ and C₂ are the outer loop capacitors for the two integrated oversampling A/D
converters. The value of these capacitors is 560pF.
The actual values determine signal to noise and stability performance. The optimum
tolerances 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.
R , R and R are the resistors defining the current level into the current sense input.
21
SH
The values should be selected for an input current of 16µA into the SA9106AP
RMS
at rated line current.
Values for RSH of less than 200µΩ should be avoided.
R = R = (I /16µA ) * R /2
1
2
L
RMS
SH
Where
I_L = Line current
R_SH = Shunt resistor/termination resistor
R , R and R set the current for the voltage sense input. The values should be
35
4
selected so that the input current into the voltage sense input (virtual ground) is set
to 14µA.
R₇ defines all on-chip bias and reference currents. With R₇ = 24kΩ, optimum
conditions are set.
XTAL is a colour burst TV crystal (f = 3.5795MHz) for the oscillator. The oscillator
frequency is divided down to 1.7897MHz on-chip and supplies the A/D converters
and the digital circuitry.
sames
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