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Atmel-46104A-SE-M90E36A-ApplicationNote_050514
APPLICATION OUTLINE
This document describes system application issues when using the M90E36A (poly-
phase energy metering ICs) to design poly-phase energy meters.
The M90E36A is applicable in class 0.5S or class 1 poly-phase meter design and also
supports three-phase four-wire (3P4W, Y0) or three-phase three-wire (3P3W, Y or Δ)
connection modes. The M90E36A can also be used in harmonic meter design.
The M90E36A uses 3.3V single power supply. In a typical 3P4W design, there are three
transformers®ulators to provide power supply. The AC power supply outputs 3.3V to
chip digital power supply DVDD after rectifier and voltage regulation. The analog power
supply AVDD should be connected directly to digital power supply DVDD.
The M90E36A has on-chip power-on-reset circuit. The RESET pin should be connected to
DVDD through a 10k
Ω resistor and a 0.1μF filter capacitor to ground. The M90E36A has
highly stable on-chip reference power supply. The Vref pin should be decoupled with a
10μF capacitor and a 0.1μF ceramic capacitor.
The M90E36A employs 16.384MHz as the system frequency. The M90E36A has built-in
crystal oscillator circuit and 10pF matching capacitance. Users only need to connect a
16.384MHz crystal between OSCI and OSCO pins in application.
The M90E36A provides a 4-wire SPI interface (CS, SCLK, SDI and SDO) for external MCU
connection. MCU can perform chip configuration and register reading/writing through SPI.
The M90E36A also supports Master mode SPI, which is named Direct Memory Access
(DMA) mode. In DMA mode, The M90E36A streams out ADC sampling raw data to
external MCU at an up to 1800kbps rate.
The M90E36A provides four energy pulse output pins: active energy pulse CF1, reactive
energy pulse CF2 (can also be configured as apparent energy pulse), fundamental energy
pulse CF3 and harmonic energy pulse CF4. They can be used for energy metering cali-
bration and can also be connected to MCU for energy accumulation.
The M90E36A provides three zero-crossing pins ZX0, ZX1 and ZX2 which can select
different phase’s voltage or current as inputs.
The M90E36A provides three output pins IRQ0, IRQ1 and WarnOut to generate interrupt
and warn out signals at different levels.
The default application in this document is 3P4W, otherwise it will be specially indicated.
Application Note
Poly-Phase Energy Metering IC
M90E36A
