DS_6618_005
78M6618 Data Sheet
1 Hardware Functional Description
1.1 Hardware Overview
The Teridian 78M6618 single-chip measurement and monitoring IC integrates all the primary AC
measurement and control blocks required to implement an 8-outlet single-phase PDU with per outlet
metering and intelligent relay control The 78M6618 includes:
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A ten-input analog front end (AFE)
An independent digital computation engine (CE)
An 8051-compatible microprocessor (MPU) which executes one instruction per clock cycle (80515)
A precision voltage reference
A temperature sensor
RAM and Flash memory
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A variety of I/O pins
LCD drivers
Various current sensor technologies are supported including Current Transformers (CT), Resistive Shunts
and Rogowski coils.
In a sub-metering application, the 32-bit compute engine (CE) of the 78M6618 sequentially process the
samples from the analog inputs on pins IA, IB, IC, ID, IE, IF, IG, IH, VA, VB and performs calculations to
measure active energy (Wh) and reactive energy (VARh), as well as A2h and V2h for four-quadrant
measurement. These measurements are then accessed by the MPU, processed further, and output via
the peripheral devices available to the MPU.
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
undesirable temperature effects on measurement accuracy. Temperature-dependent external
components such as a crystal oscillator and current sensors can be characterized and their correction
factors can be programmed to produce measurements with exceptional accuracy over the industrial
temperature range.
A block diagram of the 78M6618 IC is shown in Figure 1. A detailed description of the various functional
blocks follows.
Rev. 1.4
5
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
