90E21 Datasheet, PDF (37/57 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
5.4 ENERGY REGISTER
Theory of Energy Registers
The internal energy resolution is 0.01 pulse. Within 0.01 pulse, forward and
reverse energy are counteracted. When energy exceeds 0.01 pulse, the respec-
tive forward/reserve energy is increased. The forward and reverse energy are
not counteracted in absolute energy registers. Take the example of active
energy, suppose:
T0: Forward energy is 12.34 pulses and reverse energy is 1.23 pulses;
From T0 to T1: 0.005 forward pulse appeared
From T1 to T2: 0.004 reverse pulse appeared
From T2 to T3: 0.003 reverse pulse appeared
Forward Active Pulse
Reserve Active Pulse
Absolute Active Pulse
T0
12.34
1.23
13.57
T1
12.345
1.23
13.575
T2
12.341
1.23
13.579
T3
12.34
1.232
13.582
When forward/reverse energy or absolute energy reaches 0.1 pulse, the respec-
tive register is updated. When forward/reverse energy or absolute energy
reaches 1 pulse, CFx pins output pulse and the REVP/REVQ bits (EnStatus,
46H) are updated.
Absolute energy might be more than the sum of forward and reverse energies. If
“consistency” is required between absolute energy and forward/reverse energy
in system application, absolute energy can be obtained by calculating the read-
out of the forward and reverse energy registers.
APenergy
Forward Active Energy
Address: 40H
Type: Read/Clear
Default Value: 0000H
15
14
APenergy15
APenergy14
7
6
APenergy7
APenergy6
13
APenergy13
5
APenergy5
12
APenergy12
4
APenergy4
11
APenergy11
3
APenergy3
10
APenergy10
2
APenergy2
9
APenergy9
1
APenergy1
8
APenergy8
0
APenergy0
Bit
15 - 0
Name
Description
Forward active energy; cleared after read.
APenergy[15:0] Data format is XXXX.X pulses. Resolution is 0.1 pulse. Maximum is 6553.5 pulses.
When the accumulation of this register has achieved FFFFH, the continuation accumulation will return to 0000H.
ANenergy
Reverse Active Energy
Address: 41H
Type: Read/Clear
Default Value: 0000H
15
14
ANenergy15
ANenergy14
7
6
ANenergy7
ANenergy6
13
ANenergy13
5
ANenergy5
12
ANenergy12
4
ANenergy4
11
ANenergy11
3
ANenergy3
10
ANenergy10
2
ANenergy2
9
ANenergy9
1
ANenergy1
8
ANenergy8
0
ANenergy0
Bit
15 - 0
Name
Description
Reverse active energy, cleared after read.
ANenergy[15:0] Data format is XXXX.X pulses. Resolution is 0.1 pulse. Maximum is 6553.5 pulses.
When the accumulation of this register has achieved FFFFH, the continuation accumulation will return to 0000H.
Register
37
January 10, 2012