71M6xxx Data Sheet

9

MPU

RTC

TIMERS

IADC0

VADC8 (VA)

IADC2

VADC9 (VB)

XIN

XOUT

RX

TX

TX

RX

COM0...5

V3P3A V3P3SYS

VBAT

VBAT_RTC

IADC4

VADC10 (VC)

SEG

GNDA GNDD

SEG/DIO

DIO

ICE

C

B

A

NEUTRAL

LOAD

8888.8888

PULSES,

DIO

IR

AMR

POWER FAULT

COMPARATOR

MODUL-

ATOR

SERIAL PORTS

OSCILLATOR/

PLL

MUX and ADC

LCD DRIVER

DIO, PULSES

COMPUTE

ENGINE

FLASH

MEMORY

RAM

32 kHz

REGULATOR

Shunt Current Sensors

POWER SUPPLY

71M6543F/

71M6543H

TEMPERATURE

SENSOR

VREF

IADC6

BATTERY

PWR MODE

CONTROL

WAKE-UP

NEUTRAL

I

EEPROM

9/17/2010

IADC1

IADC3

IADC5

IADC7

RTC

BATTERY

V3P3D

BATTERY

MONITOR

SPI INTERFACE

HOST

LCD DISPLAY

Pulse Transformers

3x 71M6xx3

Note: This system is referenced to Neutral

*IN = Neutral Current

Figure 4: Current Sensors Connected to the 71M6543F/H or 71M6545/H with Three 71M6xx3

3.4

PCB Layout Considerations

To limit emissions and susceptibility to electromagnetic and magnetic fields, the signal wiring between the

shunt resistors and the 71M6xxx should be as short as possible and should consist of tightly twisted pair

cable. Similarly, the PCB traces between the 71M6xxx and the 71M654x should be routed as short as

possible and should be surrounded by grounded copper structures. The trace pairs should be routed as

close to each other as permitted by the PCB manufacturer.

The copper separation (gap) between the shunt side and the 71M654x side of the signal transformer

should be as wide as permitted by the footprint of the transformer, as shown in Figure 5.