90E21 Datasheet, PDF (31/57 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
CS1
Checksum 1
Address: 2CH
Type: Read/Write
Default Value: 0000H
15
CS1_15
7
CS1_7
14
CS1_14
6
CS1_6
13
CS1_13
5
CS1_5
12
CS1_12
4
CS1_4
11
CS1_11
3
CS1_3
10
CS1_10
2
CS1_2
9
CS1_9
1
CS1_1
8
CS1_8
0
CS1_0
Bit
Name
Description
The CS1 register should be written after the 21H-2BH registers are written. Suppose the high byte and the low byte of the 21H-
2BH registers are shown in below table.
15 - 0
CS1[15:0]
Register Address
21H
22H
23H
24H
25H
26H
27H
28H
29H
2AH
2BH
The calculatiion of the CS1 register is as follows:
High Byte
H₂₁
H₂₂
H₂₃
H₂₄
H₂₅
H₂₆
H₂₇
H₂₈
H₂₉
H_2A
H_2B
Low Byte
L₂₁
L₂₂
L₂₃
L₂₄
L₂₅
L₂₆
L₂₇
L₂₈
L₂₉
L_2A
L_2B
The low byte of 2CH register is: L_2C=MOD(H₂₁+H₂₂+...+H_2B+L₂₁+L₂₂+...+L_2B, 2^8)
The high byte of 2CH register is: H_2C=H₂₁ XOR H₂₂ XOR ... XOR H_2B XOR L₂₁ XOR L₂₂ XOR ... XOR L_2B
For 90E21/22/23, a part of registers are not used. These registers can be dealed as 0000H in CS calculation.
The 90E21/22/23/24 calculates CS1 regularly. If the value of the CS1 register and the calculation by the 90E21/22/23/24 is differ-
ent when CalStart=8765H, the CalErr[1:0] bits (SysStatus, 01H) are set and the WarnOut and IRQ pins are asserted.
Note: The readout value of the CS1 register is the calculation by the 90E21/22/23/24, which is different from what is written.
Register
31
January 10, 2012