71M6541DSLASHFSLASHG datasheet(12/166 Pages) MAXIM

12 / 166 page

71M6541D/F/G and 71M6542F/G Data Sheet

Rev 5

transformers (CTs) and their corresponding signal conditioning circuits can be characterized and their

correction factors can be programmed to produce electricity meters with exceptional accuracy over the

industrial temperature range.

One of the two internal UARTs is adapted to support an Infrared LED with internal drive and sense configuration

and can also function as a standard UART. The optical output can be modulated at 38 kHz. This flexibility

makes it possible to implement AMR meters with an IR interface. A block diagram of the IC is shown in

Figure 1.

2.2

Analog Front End (AFE)

The AFE functions as a data acquisition system, controlled by the MPU. When used with locally

connected sensors, as seen in Figure 2, the analog input signals (IAP-IAN, VA and IBP-IBN) are

multiplexed to the ADC input and sampled by the ADC. The ADC output is decimated by the FIR filter

and stored in CE RAM where it can be accessed and processed by the CE.

See Figure 6 for the multiplexer sequence corresponding to Figure 2. See Figure 35 for the meter

configuration corresponding to Figure 2.

DS ADC

CONVERTER

VREF

MUX

VREF

VADC

FIR

IBP

IAP

VADC10 (VA)

IAN

IBN

71M6541D/F

CE RAM

*IN = Optional Neutral Current

Local

Shunt

IN*

ILINE

11/5/2010

ILINE

Figure 2. 71M6541D/F/G AFE Block Diagram (Local Sensors)

71M6541D/F/G Datasheet(PDF) 12 Page - Maxim Integrated Products