90E21 datasheet(12/57 Pages) IDT

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90E21/22/23/24

SINGLE-PHASE HIGH-PERFORMANCE WIDE-SPAN ENERGY METERING IC

Functional Description

January 10, 2012

FUNCTIONAL DESCRIPTION

3.1

DYNAMIC METERING RANGE

Accuracy is 0.1% for active energy metering and 0.2% for reactive

energy metering over a dynamic range of 5000:1 (typical). Refer to

Table-3 and Table-4.

3.2

STARTUP AND NO-LOAD POWER

Startup and no-load power thresholds are programmable, both for

active and reactive power. The related registers are listed in Table-5.

The chip will start within 1.2 times of the theoretical startup time of

the configured startup power, if startup power is less than the corre-

sponding power of 20mA when power factor or sinφ is 1.0.

The chip has no-load status bits, the Pnoload/Qnoload bit (EnStatus,

46H). The chip will not output any active pulse (CF1) in active no-load

state. The chip will not output any reactive pulse (CF2) in reactive no-

load state.

3.3

ENERGY REGISTERS

The 90E21/22/23/24 provides energy pulse output CFx (CF1/CF2)

which is proportionate to active/reactive energy. Energy is usually accu-

mulated by adding the CFx pulses in system applications. Alternatively,

the 90E21/22/23/24 provides energy registers. There are forward

(inductive), reverse (capacitive) and absolute energy registers for both

active and reactive energy. Refer to Table-6.

Each energy register is cleared after read. The resolution of energy

registers is 0.1CF, i.e. one LSB represents 0.1 energy pulse.

Table-3 Active Energy Metering Error

Current

Power Factor

Error(%)

20mA ≤ I ＜ 50mA

1.0

0.2

50mA ≤ I ≤ 100A

0.1

50mA ≤ I ＜ 100mA

0.5 (Inductive)

0.8 (Capacitive)

0.2

100mA ≤ I ≤ 100A

0.1

Note: Shunt resistor is 250

µΩ or CT ratio is 1000:1 and load resistor is 6Ω.

Table-4 Reactive Energy Metering Error

Current

sin

φ (Inductive or

Capacitive)

Error(%)

20mA ≤ I ＜ 50mA

1.0

0.4

50mA ≤ I ≤ 100A

0.2

50mA ≤ I ＜ 100mA

0.5

0.4

100mA ≤ I ≤ 100A

0.2

Note: Shunt resistor is 250

µΩ or CT ratio is 1000:1 and load resistor is 6Ω.

Table-5 Threshold Configuration for Startup and No-Load Power

Threshold

Threshold for Active Startup Power

PStartTh, 27H

Threshold for Active No-load Power

PNolTh, 28H

Threshold for Reactive Startup Power

QStartTh, 29H

Threshold for Reactive No-load Power

QNolTh, 2AH

Table-6 Energy Registers

Energy

Forward Active Energy

APenergy, 40H

Reverse Active Energy

ANenergy, 41H

Absolute Active Energy

ATenergy, 42H

Forward (Inductive) Reactive Energy

RPenergy, 43H

Reverse (Capacitive) Reactive Energy

RNenergy, 44H

Absolute Reactive Energy

RTenergy, 45H

90E21 Datasheet(PDF) 12 Page - Integrated Device Technology

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