71M6533 Datasheet, PDF (9/132 Pages) Teridian Semiconductor Corporation – Energy Meter IC

FDS_6533_6534_004
71M6533/G/H and 71M6534/H Data Sheet
1 Hardware Description
1.1 Hardware Overview
The Teridian 71M6533 and 71M6534 single-chip energy meter integrate all primary functional blocks
required to implement a solid-state electricity meter. Included on the chip are:
• An analog front end (AFE)
• An Independent digital computation engine (CE)
• An 8051-compatible microprocessor (MPU) which executes one instruction per clock cycle (80515)
• A voltage reference
• A temperature sensor
• LCD drivers
• RAM and Flash memory
• A real time clock (RTC)
• A variety of I/O pins
Various current sensor technologies are supported including Current Transformers (CT), Resistive Shunts
and Rogowski coils.
In a typical application, the 32-bit compute engine (CE) of the 71M6533/71M6534 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 A²h, 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 function allows the 71M6533/71M6534
to record time of use (TOU) metering information for multi-rate applications and to time-stamp tamper
events. Measurements can be displayed on 3.3 V LCDs commonly used in low-temperature environments.
Flexible mapping of LCD display segments facilitate integration of existing custom LCDs. Design trade-offs
between the number of LCD segments and DIO pins can be implemented in software to accommodate
various requirements.
In addition to the temperature-trimmed ultra-precision voltage reference, the on-chip digital temperature
compensation mechanism includes a temperature sensor and associated controls for correction of unwanted
temperature effects on measurement and RTC accuracy, e.g. to meet the requirements of ANSI and IEC
standards. Temperature dependent external components such as a crystal oscillator, current 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.
1.2 Analog Front End (AFE)
The AFE of the 71M6533/71M6534 consists of an input multiplexer, a delta-sigma A/D converter and a
voltage reference.
1.2.1 Signal Input Pins
All analog signal input pins are sensitive to voltage. The VA, VB, and VC pins are single-ended. Pins
IAP/IAN, IBP/IBN, ICP/ICN, and IDP/IDN can be programmed individually to be differential or single-ended.
The differential signal is applied between the InP and InN input pins. Single-ended signals are applied to
the InP input while the common signal, return, is the V3P3A pin. When using the differential mode, inputs
can be chopped, i.e., a connection from V3P3A to InP or InN alternates in each multiplexer cycle.
Rev 2
9