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SA9602MSA

SINGLE PHASE POWER/ENERGY METERING IC WITH SELECTABLE PULSE RATE FOR MECHANICAL DISPLAY APPLICATIONS

South African Micro Electronic Systems 

SA9602M

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 SA9602M integrated circuit are:

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 16µA into the SA9602M at

RMS

maximum line current.

Values for RSH of less than 200µΩ should be avoided.

R = R = (I /16µA ) * R /2

1

2

L

RMS

SH

Where IL

= Line current

RSH = 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.

R defines all on-chip bias and reference currents.

7

With

R

7

=

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%).

The formula for calculating the output frequency is given below:

fLED= 11.16

* FOUTX * FOSC * II .IV

3.58MHz IR2

Where FOUTX = Frequency for selected rated condition

FOSC = Oscillator frequency (2MHz ...... 4MHz)

II

= Input current for current input (16µARMS at rated)

IV

= Input current for voltage input (14µARMS at rated)

I

= Reference current

(typically 50µA)

R

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.

sames

11/16

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