71M6543F datasheet(11/157 Pages) MAXIM

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71M6543F/H and 71M6543G/GH Data Sheet

v1.2

Hardware Description

2.1

Hardware Overview

The Teridian 71M6543 single-chip energy meter integrates all primary functional blocks required to

implement a solid-state electricity meter. Included on the chip are:

•

An analog front-end (AFE) featuring a 22-bit second-order sigma-delta ADC

•

An independent 32-bit digital computation engine (CE) to implement DSP functions

•

An 8051-compatible microprocessor (MPU) which executes one instruction per clock cycle (80515)

•

A precision voltage reference (VREF)

•

A temperature sensor for digital temperature compensation of:

Metrology (MPU)

Automatic RTC in all power states

MPU assisted RTC compensation

•

LCD Driver

•

RAM and Flash memory

•

A real time clock (RTC)

•

A variety of I/O pins

•

A power failure interrupt

•

A zero-crossing interrupt

•

Selectable current sensor interfaces for locally-connected sensors as well as isolated sensors (i.e.,

using the 71M6xx3 companion IC with a shunt resistor sensor)

•

Resistive Shunt and Current Transformers are supported

In order to implement a polyphase meter with or without neutral current sensing, one resistive shunt

current sensor may be connected directly (non-isolated) to the 71M6543 device, while up to three

additional current shunts are isolated using a companion 71M6xx3 isolated sensor IC. An inexpensive,

small size pulse transformer is used to electrically isolate the 71M6xx3 remote sensor from the 71M6543.

The 71M6543 performs digital communications bi-directionally with the 71M6xx3 and also provides power

to the 71M6xx3 through the isolating pulse transformer. Isolated (remote) shunt current sensors are

connected to the differential input of the 71M6xx3. The 71M6543 may also be used with Current

Transformers; in this case the 71M6xx3 isolated sensors are not required. Included on the 71M6xx3

companion isolator chip are:

•

Digital isolation communications interface

•

An analog front-end (AFE) featuring a 22-bit second-order sigma-delta ADC

•

A precision voltage reference (VREF)

•

A temperature sensor (for current-sensing digital temperature compensation)

•

A fully differential shunt resistor sensor input

•

A pre-amplifier to optimize shunt current sensor performance

•

Isolated power circuitry obtains dc power from pulses sent by the 71M6543

In a typical application, the 32-bit compute engine (CE) of the 71M6543 sequentially processes the

samples from the voltage inputs on analog input pins and performs calculations to measure active energy

(Wh) and reactive energy (VARh), as well as A

2h, and V2h for four-quadrant metering. These measurements

are then accessed by the MPU, processed further and output using the peripheral devices available to the

MPU.

In addition to advanced measurement functions, the real time clock (RTC) function allows the 71M6543 to

record time of use (TOU) metering information for multi-rate applications and to time-stamp tamper or other

events. An automatic RTC temperature compensation circuit operates in all power states including when the

MPU is halted, and continues to compensate using back-up battery power during power outages.

Measurements can be displayed on 3.3 V LCDs commonly used in low-temperature environments. The

integrated charge pump and temperature sensor can be used by the MPU to enhance 3.3 V LCD

performance at cold temperatures. The on-chip charge pump may also drive 5 V LCDs. Flexible mapping of

LCD display segments facilitates the integration of existing custom LCDs. Design trade-off between the

71M6543F 数据表(PDF) 11 Page - Maxim Integrated Products

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