90E21 Datasheet, PDF (12/57 Pages) Integrated Device Technology – Single-Phase High-Performance Wide-Span Energy Metering IC

90E21/22/23/24
SINGLE-PHASE HIGH-PERFORMANCE WIDE-SPAN ENERGY METERING IC
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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.
Table-3 Active Energy Metering Error
Current
Power Factor
Error(%)
20mA ≤ I ＜ 50mA
1.0
50mA ≤ I ≤ 100A
±0.2
±0.1
50mA ≤ I ＜ 100mA
100mA ≤ I ≤ 100A
0.5 (Inductive)
0.8 (Capacitive)
±0.2
±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
sinφ (Inductive or
Capacitive)
Error(%)
20mA ≤ I ＜ 50mA
1.0
50mA ≤ I ≤ 100A
±0.4
±0.2
50mA ≤ I ＜ 100mA
0.5
100mA ≤ I ≤ 100A
±0.4
±0.2
Note: Shunt resistor is 250 µΩ or CT ratio is 1000:1 and load resistor is 6Ω.
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.
Table-5 Threshold Configuration for Startup and No-Load Power
Threshold
Threshold for Active Startup Power
Threshold for Active No-load Power
Threshold for Reactive Startup Power
Threshold for Reactive No-load Power
Register
PStartTh, 27H
PNolTh, 28H
QStartTh, 29H
QNolTh, 2AH
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.
Table-6 Energy Registers
Energy
Forward Active Energy
Reverse Active Energy
Absolute Active Energy
Forward (Inductive) Reactive Energy
Reverse (Capacitive) Reactive Energy
Absolute Reactive Energy
Register
APenergy, 40H
ANenergy, 41H
ATenergy, 42H
RPenergy, 43H
RNenergy, 44H
RTenergy, 45H
Each energy register is cleared after read. The resolution of energy
registers is 0.1CF, i.e. one LSB represents 0.1 energy pulse.
Functional Description
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January 10, 2012