SA9105E

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PIN DESCRIPTION (Continued)

Pin

Pin

PLCC

DIP

12

NC

Not connected

24

NC

34

NC

44

NC

Designation

Description

FUNCTIONAL DESCRIPTION

The SAMES SA9105E is a CMOS mixed signal Analog/Digital integrated circuit, which

performs three phase power/energy calculations over a range of 1000:1, to an overall

accuracy of better than Class 1.

The integrated circuit includes all the required functions for 3-phase power and energy

measurement such as oversampling A/D converters for the voltage and current sense

inputs, power calculation and energy integration. Internal offsets are eliminated through

the use of cancellation procedures.

The SA9105E generates pulses, the frequency of which is proportional to the power

consumption. Three frequency outputs (FOUT1, FOUT2 and FOUT3) are available. The

pulse rate follows the instantaneous power measured.

1.

Power Calculation

In the Application Circuit (Figure 1), the mains voltages from Line 1, Line 2 and Line

3, are converted to currents and applied to the voltage sense inputs IVP1, IVP2 and

IVP3.

The current levels on the voltage sense inputs are derived from the mains voltage

(3 x 230 VAC) being divided down through voltage dividers to 14V. The resulting

input currents into the A/D converters are 14

µA through the resistors R

R

For the current sense inputs the voltage drop across the current transformers

terminating resistors are converted to currents of 16

µA for rated conditions, by

means of resistors R

The signals providing the current information are applied to the current sensor inputs

IIN1, IIP1; IIN2, IIP2 and IIN3, IIP3.

In this configuration, with the mains voltage of 3 x 230 V and rated currents of 80A,

the output frequency of the SA9105E energy metering integrated circuit at FOUT1

is 1.16kHz. In this case 1 pulse will correspond to an energy consumption of 3 x 18.4

kW/1160Hz = 47.6 Ws.

The output frequency at FOUT2 is FOUT1/4. At FOUT3 the output frequency is

FOUT1/290.