ADE9178 datasheet(32/122 Pages) AD

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Data Sheet

ADE9178

THEORY OF OPERATION

analog.com

Rev. A | 32 of 122

Table 13. Terminology and Full-Scale Codes

Notation

Description

Value

Applicable Registers

IFS

RMS Current in amperes (ARMS), which gives

full-scale signal at ADC input. This is the

current that gives full scale at the ADC current

(IP) inputs of ±31.25 mV peak to peak.

Depends on system parameters. For more

details, see the example system configuration.

Depends on shunt resistor size.

VFS_T

Theoretical full-scale RMS voltage in volts

(VRMS), which gives full-scale input at ADC

input. This is the voltage that gives full scale at

the ADC voltage (V1P) inputs of ±1 V peak to

peak.

Depends on system parameters. Depends on

resistor-divider ratio.

AUXFS

Signal value (RMS) in appropriate units, which

gives full-scale value at ADC input. The units

can be either voltage or current. This is the

voltage/current that gives full scale at the

auxiliary ADC input. ±1 V peak to peak for

V1P/V2P inputs and ±31.25 mV peak to peak

for IP input, which depends on the ADC Mux

settings.

Depends on system parameters.

RMSFS_CODES

RMS output register value when full-scale input

is applied to the ADC input.

107310840

xRMS, xRMSONE, xRMSHALF, xDIP, xSWELL,

xPEAK

POWFS_CODES

Power output register value when full-scale

voltage and current of same phase is applied at

the ADC input.

85829040

xWATT, xVA

PCFFS_CODES

Phase compensation filter (PCF) output for

waveform streaming.

6706531

Meter constant (impls/kWHr), which defines the

frequency of the CF pulse output.

System Configuration. Supported between 100

and 10000.

The format for configuration registers for each feature are given

along with description of appropriate features are shown in the

following sections. To convert output registers to physical quantities,

use the following equations shown in Table 14.

Table 14. Conversion Equations

Purpose

Equation

Unit

Applicable registers

RMS related output calculation

XFS

RMSFS_CODES ×X

(1)

XRMS

Where, X = xRMS,

xRMSONE, xRMSHALF, xDIP,

xSWELL, xPEAK

Power calculation

IFS×VFS_T

POWFS_CODES ×X

(2)

watt, VA

Where, X = xWATT, xVA

Energy calculation

IFS×VFS_T

POWFS_CODES × XHI≪13 +XLO

4000

(3)

watt × seconds

Where, XHI =

xWATTHR_xx_HI or

xVAHR_HI

XLO = xWATTHR_xx_LO or

xVAHR_LO

Power factor

xPF×2−27

APF, BPF, and CPF

Period calculation

xPERIOD+1

4000×216

(4)

seconds

xPERIOD, PEN_PERIOD

Angle calculation

2πANGL_X_Y×256

xPERIOD+1 −2π

(5) radians

ANGL_X_Y, where, X and Y

are phase voltage or currents.

For example, ANGL_AV_BV

or ANGL_BI_CI

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