SA9102F/SA9102H

sames

7/14

The formula for calculating the output frequency (f) is given below:

f = 11.16 * FOUTX *

FOSC

*

I

3.58MHz

I

R

2

Where FOUTX

= Nominal rated frequency (64Hz)

FOSC

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

I

I

= Input currents for current inputs (16µA at rated)

I

V

= Input currents for voltage inputs (14µA at rated)

I

R

= Reference current (typically 50µA)

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 digital circuitry and the

A/d converters.

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 SA9102F and SA9102H integrated

circuits are:

C

converters. The value of these capacitors is 560pF.

The actual values determine signal to noise and stability performance. The tolerances

should be within ±10%.

C

The optimum value is

3.3nF. The actual values are uncritical. Values smaller than 0.5nF and larger than 5nF

should be avoided.

R

The values should be selected for an input current of 16µA into the SA9102F/SA9102H

at maximum line current.

Values for RSH of less than 200µ

Ω should be avoided.

R

Where

I

L

=

Line current

RSH

=

Shunt resistor/termination resistor