71M6543F Datasheet, PDF (19/157 Pages) Maxim Integrated Products – Selectable Gain of 1 or 8 for One Current Energy Meter ICs Metrology Compensation

71M6543F/H and 71M6543G/GH Data Sheet
Delay compensation and other functions in the CE code require the settings for MUX_DIV[3:0],
MUXn_SEL[3:0], RMT_E, FIR_LEN[1:0], ADC_DIV and PLL_FAST to be fixed for a given CE code.
Refer to Table 1 and Table 2 for the settings that are applicable to the 71M6543.
Table 3 summarizes the I/O RAM registers used for configuring the multiplexer, signals pins, and ADC. All
listed registers are 0 after reset and wake from battery modes, and are readable and writable.
Table 3: Multiplexer and ADC Configuration Bits
Name
Location Description
MUX0_SEL[3:0] 2105[3:0] Selects the ADC input converted during time slot 0.
MUX1_SEL[3:0] 2105[7:4] Selects the ADC input converted during time slot 1.
MUX2_SEL[3:0] 2104[3:0] Selects the ADC input converted during time slot 2.
MUX3_SEL[3:0] 2104[7:4] Selects the ADC input converted during time slot 3.
MUX4_SEL[3:0] 2103[3:0] Selects the ADC input converted during time slot 4.
MUX5_SEL[3:0] 2103[7:4] Selects the ADC input converted during time slot 5.
MUX6_SEL[3:0] 2102[3:0] Selects the ADC input converted during time slot 6.
MUX7_SEL[3:0] 2102[7:0] Selects the ADC input converted during time slot 7.
MUX8_SEL[3:0] 2101[3:0] Selects the ADC input converted during time slot 8.
MUX9_SEL[3:0] 2101[7:0] Selects the ADC input converted during time slot 9.
MUX10_SEL[3:0] 2100[3:0] Selects the ADC input converted during time slot 10.
ADC_DIV
2200[5] Controls the rate of the ADC and FIR clocks.
MUX_DIV[3:0] 2100[7:4] The number of ADC time slots in each multiplexer frame (maximum = 11).
PLL_FAST
FIR_LEN[1:0]
2200[4] Controls the speed of the PLL and MCK.
210C[2:1] Determines the number of ADC cycles in the ADC decimation FIR filter.
DIFF0_E
210C[4] Enables the differential configuration for analog input pins IADC0-IADC1 .
DIFF2_E
210C[5] Enables the differential configuration for analog input pins IADC2-IADC3 .
DIFF4_E
210C[6] Enables the differential configuration for analog input pins IADC4-IADC5 .
DIFF6_E
210C[7] Enables the differential configuration for analog input pins IADC6-IADC7 .
RMT2_E
2709[3]
Enables the remote sensor interface transforming pins IADC2-IADC3 into a digital
interface for communications with a 71M6xx3 sensor.
RMT4_E
2709[4]
Enables the remote sensor interface transforming pins IADC4-IADC5 into a digital
interface for communications with a 71M6xx3 sensor.
RMT6_E
2709[5]
Enables the remote sensor interface transforming pins IADC6-IADC7 into a digital
interface for communications with a 71M6xx3 sensor.
PRE_E
2704[5] Enables the 8x pre-amplifier.
Refer to Table 71 starting on page 104 for more complete details about these I/O RAM locations.
2.2.3 Delay Compensation
When measuring the energy of a phase (i.e., Wh and VARh) in a service, the voltage and current for that
phase must be sampled at the same instant. Otherwise, the phase difference, Ф, introduces errors.
φ
=
t_delay
T
⋅ 360^o
=
t_delay
⋅
f
⋅ 360^o
Where f is the frequency of the input signal, T = 1/f and t_delay is the sampling delay between current and
voltage.
Traditionally, sampling is accomplished by using two A/D converters per phase (one for voltage and the
other one for current) controlled to sample simultaneously. Teridian’s Single-Converter Technology^®,
however, exploits the 32-bit signal processing capability of its CE to implement “constant delay” all-pass
filters. The all-pass filter corrects for the conversion time difference between the voltage and the
corresponding current samples that are obtained with a single multiplexed A/D converter.
The “constant delay” all-pass filter provides a broad-band delay 360^o - θ, which is precisely matched to
the difference in sample time between the voltage and the current of a given phase. This digital filter does
not affect the amplitude of the signal, but provides a precisely controlled phase response.
v1.2
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