71m6511h-igtr Maxim Integrated Products, Inc., 71m6511h-igtr Datasheet - Page 8

• Manufacturer Part Number: 71m6511h-igtr
• Description: Single-phase Energy Meter Ic
• Manufacturer: Maxim Integrated Products, Inc.

HARDWARE DESCRIPTION
The TERIDIAN 71M6511 single chip single-phase meter integrates all primary functional blocks required to implement a solid-
state electricity meter. Included on chip are an analog front end (AFE), an 8051-compatible microprocessor (MPU) which
executes one instruction per clock cycle (80515), an independent 32-bit digital computation engine (CE), a voltage reference, a
temperature sensor, LCD drivers, RAM, FLASH memory, a real time clock (RTC), and a variety of I/O pins. Various current
sensor technologies are supported including Current Transformers (CT), Resistive Shunts, and Rogowski (di/dt) Coils.
In addition to advanced measurement functions, the real time clock function allows the 71M6511/6511H to record time of use
(TOU) metering information for multi-rate applications. Measurements can be displayed on either a 3V or a 5V LCD. Flexible
mapping of LCD display segments will facilitate integration with any LCD format. The design trade-off between the number of
LCD segments and DIO pins can be flexibly configured using memory-mapped I/O to accommodate various requirements.
The 71M6511 includes several I/O peripheral functions that improve the functionality of the device and reduce the component
count for most meter applications. The I/O peripherals include two UARTs, digital I/O, comparator inputs, LCD display drivers,
I
One of the two internal UARTs (UART1) is adapted to support an Infrared LED with internal drive output and sense input but it
can also function as a standard UART.
A block diagram of the chip is shown in Figure 1. A detailed description of various hardware blocks follows.
The AFE of the TERIDIAN 71M6511 Power Meter IC is comprised of an input multiplexer, a delta-sigma A/D converter with a
voltage reference, followed by an FIR filter. A block diagram of the AFE is shown in Figure 3.
Multiplexer
The input multiplexer supports four input signals that are applied to the pins IA, VA, and IB plus the output of the internal
temperature sensor. The multiplexer can be operated in two modes:
Alternate multiplexer cycles are usually performed infrequently (every second or so). VA is not replaced in the alternate multi-
plexer cycles. Missing samples due to alternate multiplexer cycles are automatically interpolated by the CE.
In a typical application, the IA input is connected to a current transformer that senses the line current. VA is typically connected
to a voltage sensor through resistor dividers. IB may be connected to a second current transformer, e.g. for optional tamper
detection.
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C interface and an optical/IR interface.
•
•
During a normal multiplexer cycle, the signals from the pins IA, VA, and IB, are selected.
During the alternate multiplexer cycle, the temperature signal (TEMP) is selected, along with the other signal sources
shown in Table 1.
EQU
000
001
Table 1: Inputs Selected in Regular and Alternate Multiplexer Cycles
Channels used from MUX
Sequence
States 0 → 3
IA
IA
0
© 2005-2007 TERIDIAN Semiconductor Corporation
VA
VA
1
Analog Front End (AFE)
Hardware Overview
IB
IB
2
3
-
-
Channels used from alternative
MUX Sequence
States 0 → 3
Single-Phase Energy Meter IC
TEMP
TEMP
0
71M6511/71M6511H
VA
VA
1
DATA SHEET
IB
2
-
3
-
-
AUGUST 2007
V2.6