PM9603AP データシートの表示（PDF） - South African Micro Electronic Systems

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PM9603AP

SINGLE PHASE POWER/ENERGY METERING MODULE SPI INTERFACE

South African Micro Electronic Systems 

PM9603AP

The current sense input requires a differential approach to cater for precision across

the dynamic range. It is therefore important that the PC board layout of the branches

to the sensing element, are as symmetrical as possible and the loop area is kept to

a minimum.

The most important external components for the SA9603B 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 16µARMS into the SA9603B at

rated line current.

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

R = R = (I /16µA ) * RSH/2

1

2

L

RMS

Where I = Line current

L

RSH = Shunt resistor/termination resistor

R , R and R set the current for the voltage sense input. The values should be

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4

selected so that the input current into the voltage sense input (virtual ground) is set

to 14µARMS.

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.

7. Demonstration Software

Software which runs under Windows 3.1 and Windows 95 is provided with each

evaluation module. See README.TXT on the diskette supplied for the installation

instructions.

8. Sample C source code

The following software demonstrates how to synchronize the reading of the registers

to the SA9603B's internal offset cancellation scheme. The software is also available

on the SAMES Internet web pages.

sames

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