90E21 datasheet(37/57 Pages) IDT

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90E21/22/23/24

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

January 10, 2012

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

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

ANenergy

Reverse Active Energy

Forward Active Pulse

12.34

12.345

12.341

12.34

Reserve Active Pulse

1.23

1.232

Absolute Active Pulse

13.57

13.575

13.579

13.582

Address: 40H

Type: Read/Clear

Default Value: 0000H

Bit

Name

Description

15 - 0

APenergy[15:0]

Forward active energy; cleared after read.

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.

Address: 41H

Type: Read/Clear

Default Value: 0000H

Bit

Name

Description

15 - 0

ANenergy[15:0]

Reverse active energy, cleared after read.

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.

APenergy15

APenergy14

APenergy13

APenergy12

APenergy11

APenergy10

APenergy9

APenergy8

765

432

APenergy7

APenergy6

APenergy5

APenergy4

APenergy3

APenergy2

APenergy1

APenergy0

ANenergy15

ANenergy14

ANenergy13

ANenergy12

ANenergy11

ANenergy10

ANenergy9

ANenergy8

765

432

ANenergy7

ANenergy6

ANenergy5

ANenergy4

ANenergy3

ANenergy2

ANenergy1

ANenergy0

90E21 Datasheet(PDF) 37 Page - Integrated Device Technology

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