71M6513 Maxim, 71M6513 Datasheet - Page 9

• Manufacturer Part Number: 71M6513
• Description: The 71M6513 and 71M6513H are highly integrated SoCs with an MPU core, RTC, flash, and LCD driver
• Manufacturer: Maxim

HARDWARE DESCRIPTION
The 71M6513 single-chip polyphase 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 71M6513/6513H 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 71M6513 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 71M6513 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 eight input signals that are applied to the pins IA, VA, IB, VB, IC, VC, and V3 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, VB, and VC are not replaced in the
alternate multiplexer cycles. In some equations, currents must be delayed in allpass networks and therefore cannot be
replaced in the alternate selection. Missing samples due to alternate multiplexer cycles are automatically interpolated by the
CE.
In a typical application, the IA, IB, and IC inputs are connected to current transformers that sense the current on each phase of
the line voltage. VA, VB, and VC are typically connected to voltage sensors through resistor dividers.
The Multiplexer Control Circuit handles the setting of the multiplexer. The function of the Multiplexer Control Circuit is
governed by the I/O RAM registers MUX_ALT (0x2005[2]), EQU (0x2000[7:5]), and MUX_DIV (0x2002[7:6]). MUX_DIV controls
the number of samples per cycle. It can request 2, 3, 4, or 6 multiplexer states per cycle.
2
C interface and an optical/IR interface.
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•
During a normal multiplexer cycle, the signals from the six pins IA, VA, IB, VB, IC, and VC are selected.
During the alternate multiplexer cycle, the temperature signal (TEMP) and the additional monitor input, V3, are
selected, along with the other signal sources shown in Table 1: Inputs Selected in Regular and Alternate Multiplexer
Cycles.
A Maxim Integrated Products Brand
Regular multiplexer sequence
Mux State:
IA
0
Table 1: Inputs Selected in Regular and Alternate Multiplexer Cycles
VA
1
IB
2
VB
© 2005-2011 Teridian Semiconductor Corporation
3
Analog Front End (AFE)
IC
4
Hardware Overview
VC
5
Alternate multiplexer sequence
Mux State:
TEMP
0
3-Phase Energy Meter IC
VA
1
71M6513/71M6513H
V3
2
DATA SHEET
VB
3
IC
4
VC
5
SEPTEMBER 2011
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