71M6521FE-IMR/F Maxim Integrated Products, 71M6521FE-IMR/F Datasheet - Page 83

• Manufacturer Part Number: 71M6521FE-IMR/F
• Description: IC ENERGY METER 32K FLASH 68-QFN
• Manufacturer: Maxim Integrated Products

Specifications of 71M6521FE-IMR/F

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

71M6521DE/DH/FE Data Sheet
During operation, the MPU is in charge of controlling the multiplexer cycles, for example by inserting an alternate
multiplexer sequence at regular intervals using MUX_ALT. This enables temperature measurement. The polarity of
chopping circuitry must be altered for each sample. It must also alternate for each alternate multiplexer reading. This
is accomplished by maintaining CHOP_E = 00.
CE Calculations
The CE performs the precision computations necessary to accurately measure energy. These computations include
offset cancellation, products, product smoothing, product summation, frequency detection, VAR calculation, sag
detection, peak detection, and voltage phase measurement. All data computed by the CE is dependent on the
selected meter equation as given by EQU (in I/O RAM). Although EQU=0 and EQU=2 have the same element
mapping, the MPU code can use the value of EQU to decide if element 2 is used for tamper detection (typically done
by connecting VB to VA) or as a second independent element.
CE STATUS
Since the CE_BUSY interrupt occurs at 2520.6Hz, it is desirable to minimize the computation required in the interrupt
handler of the MPU. The MPU can read the CE status word at every CE_BUSY interrupt.
The CE Status Word is used for generating early warnings to the MPU. It contains sag warnings for VA as well as F0,
the derived clock operating at the fundamental input frequency. CESTATUS provides information about the status of
voltage and input AC signal frequency, which are useful for generating early power fail warnings, e.g. to initiate
necessary data storage. CESTATUS represents the status flags for the preceding CE code pass (CE busy interrupt).
Sag alarms are not remembered from one code pass to the next. The CE Status word is refreshed at every
CE_BUSY interrupt.
Rev 2
EQU
Address
0
1
2
0x7A
CE
Watt & VAR Formula
(WSUM/VARSUM)
VA IA (1 element, 2W 1φ)
with tamper detection
VA*(IA-IB)/2
(1 element, 3W 1φ)
VA*IA + VB*IB
(2 element, 4W 2φ)
Name
CESTATUS
Description
See description of CE status word below
VA*(IA-IB)/2
VAR0SUM
W0SUM/
VA*IA
VA*IA
VAR1SUM
W1SUM/
VA*IB/2
Element Input Mapping
VA*IB
VB*IB
I0SQSUM
IA-IB
IA
IA
I1SQSUM
IB
IB
IB
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