71M6521FE-IMR/F Maxim Integrated Products, 71M6521FE-IMR/F Datasheet - Page 14

• 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

The CE DRAM contains 128 32-bit words. The MPU can read and write the CE DRAM as the primary means of data
communication between the two processors.
Table 2 shows the CE DRAM addresses allocated to analog inputs from the AFE.
The CE of the 71M6521DE/DH/FE is aided by support hardware that facilitates implementation of equations, pulse
counters, and accumulators. This support hardware is controlled through I/O RAM locations EQU (equation assist),
DIO_PV and DIO_PW (pulse count assist), and PRE_SAMPS and SUM_CYCLES (accumulation assist). PRE_SAMPS
and SUM_CYCLES support a dual level accumulation scheme where the first accumulator accumulates results from
PRE_SAMPS samples and the second accumulator accumulates up to SUM_CYCLES of the first accumulator results.
The integration time for each energy output is PRE_SAMPS * SUM_CYCLES/2520.6 (with MUX_DIV = 1). CE hardware
issues the XFER_BUSY interrupt when the accumulation is complete.
Meter Equations
Compute Engine (CE) firmware and hardware for residential meter configurations implement the equations listed in
Table 3. The register EQU (located in the I/O RAM) specifies the equation to be used based on the number of phases
used for metering.
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EQU
0
1
2
1 element, 2W 1φ with neutral current sense
and tamper detection (VA connected to VB)
1 element, 3W 1φ
2 element, 4W 2φ
ADDRESS (HEX)
00
01
02
03
04
05
06
07
Description
Table 2: CE DRAM Locations for ADC Results
Table 3: Meter Equations.
NAME
TEMP
VBAT
VA
VB
IA
IB
-
-
DESCRIPTION
Phase A current
Phase A voltage
Phase B current
Phase B voltage
Not used
Not used
Temperature
Battery Voltage
VA(IA-IB)/2
Element 0
VA IA
VA IA
Watt & VAR Formula
71M6521DE/DH/FE Data Sheet
Element 1
VA IB
VB IB
N/A
Rev 2