71M6513 Maxim, 71M6513 Datasheet - Page 56

• Manufacturer Part Number: 71M6513
• Description: The 71M6513 and 71M6513H are highly integrated SoCs with an MPU core, RTC, flash, and LCD driver
• Manufacturer: Maxim

If temperature compensation or accurate reading of the die temperature is required, alternate multiplexer cycles have to be
inserted in between the regular cycles. This is done under MPU firmware control by asserting the MUX_ALT bit whenever
necessary. Since die temperature usually changes very slowly, alternate multiplexer cycles have to be inserted very
infrequently. Usually, an alternate multiplexer cycle is inserted once for every accumulation period, i.e. after each
XFER_BUSY interrupt. This sequence is shown in Figure 22.
This sequence has the disadvantage that the alternate multiplexer cycle is always operated with positive connection.
Consequently, DC offset will appear on the temperature measurement, which will decrease the accuracy of this measurement
and thus cause temperature reading and compensation to be less accurate.
The sequence shown in Figure 23 uses the CHOP_EN bits to control the chopper polarity after each XFER_BUSY interrupt.
CHOP_EN is controlled to alternate between 10 (positive) and 01 (reversed) for the first multiplexer cycle following each
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alt. MUX
Positive
cycle
cycle 1
Positive
XFER_BUSY interrupt
MUX
Accumulation Interval m
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CE_BUSY interrupt
cycle 2
versed
MUX
Re-
XFER_BUSY interrupt
Chop Polarity
Accumulation Interval m
CE_BUSY interrupt
MUX_ALT
versed
cycle 2
Chop Polarity
MUX
Re-
(falling edge)
(falling edge)
Positive
cycle 3
MUX
Positive
cycle 3
MUX
versed
cycle n
Figure 22: Sequence with Alternate Multiplexer Cycles
MUX
Re-
Figure 21: Chop Polarity w/ Automatic Chopping
cycle n
versed
MUX
Re-
alt. MUX
Positive
cycle
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Positive
cycle 1
Accumulation Interval m+1
MUX
versed
Re-
Accumulation Interval m+1
versed
Re-
Positive
Positive
3-Phase Energy Meter IC
cycle n
versed
MUX
Re-
cycle n
versed
MUX
Re-
71M6513/71M6513H
alt. MUX
Positive
cycle
Positive
DATA SHEET
cycle 1
Accumulation Interval m+2
MUX
versed
Re-
Accumulation Interval m+2
versed
Re-
Positive
Positive
AUGUST 2011