SA9105F

sames

7/12

5.

Pulse Output Signals

The calculated power is divided down to a pulse rate of 64Hz, for rated conditions

on both FOUT1 and FOUT2.

The format of the pulse output signal, which provides power/energy and direction

information, is the only difference between the signals on FOUT1 and FOUT2.

The direction of the energy flow is defined by the mark/space ratio on FOUT1, while

the pulse width defines the direction on FOUT2.

An integrated anticreep function ensures no metering at zero line currents.

DR-00950

Wave form on DIR

mm

Positive Energy Flow

Wave form on FOUT1

Wave form on FOUT2

pp = 1.1ms

pp

t

t

mm

pp

t

mm

t

mm

pn = 3.4ms

Negative Energy Flow

pn

t

t

pn

The formula for calculating the Output Frequency (f) is given below:

f = 11.16 * FOUTX *

FOSC

*

(I

3.58MHz

3 * I

R

2

Where FOUTX

= Nominal rated frequency (64Hz)

FOSC

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

I

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

I

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

I

R

= Reference current (typically 50µA)

TYPICAL APPLICATION

In the Application Circuit (Figure 1), the components required for a three phase power

metering application are shown. Terminated current transformers are used for current

sensing.

The most important external components for the SA9105F integrated circuit are: