Datasheet

Data Sheet ADE9153A
Rev. 0 | Page 21 of 50
THEORY OF OPERATION
mSURE AUTOCALIBRATION FEATURE
The ADE9153A offers mSure autocalibration technology,
enabling the automatic calibration of the current and voltage
channel accurate, automatic calibration. Autocalibration features
have two main components: absolute accuracy and the speed of
convergence (see the Terminology section for more details).
When performing autocalibration, the current channels, AI and
BI, can be run in two power modes: turbo mode and normal mode.
The power mode is a trade-off between the speed of convergence
and current consumption. In turbo mode, the speed of conver-
gence is 4× faster and the current consumption is only 2× higher
when compared to normal mode, which means that the average
consumption over a full run is less than in low power mode, but
the instantaneous consumption is higher, as shown in Figure 38.
POWER
CONSUMPTION
NORMAL
MODE
LOW POWER MODE
p0 + 2 × p1
p0 + p1
p0
0t1 4 × t1
TIME
ADE9153 A
m
Sure DISABLED
16519-038
Figure 38. mSure Autocalibration Power Modes to Same Certainty
The ADE9153A can perform the autocalibration of a meter
without requiring an accurate source or reference meter. By
powering up the meter, the CC of each channel can be measured,
and that requirement alone is enough to perform the auto-
calibration.
After the meter is powered, the autocalibration feature can be run
on each channel, one at a time, by using the MS_ACAL_CFG
register. Each channel has a set amount of run time. After each
channel finishes a run, the certainty of the measurements are
confirmed with the MS_ACAL_xCERT registers. Then, the
MS_ACAL_xCC register can be used to calculate a gain value
that calibrates the meter.
mSure System Warning Interrupts
A set of interrupts in the ADE9153A are dedicated to alerting
the user regarding any issues during an mSure autocalibration.
These alerts are all indicated as a bit in the MS_STATUS_IRQ
register, which is a Tier 2 status register as described in the
Interrupts/Events section.
The MS_CONFERR bit is set if a run of mSure is incorrectly set up
with the MS_ACAL_CFG register. Clear these registers to 0 and
check the settings being written before starting another run.
The MS_ABSENT bit is set if the mSure signal is not detected. If
this bit is triggered, wiring in the meter may be incorrect or broken.
The MS_TIMEOUT bit is set if autocalibration is left to run for
more than the 600 sec limit of the system. If this interrupt is
triggered, ensure that the runs of mSure are being correctly
handled in terms of enabling and disabling mSure when
appropriate.
The MS_SHIFT bit is set when there is a shift in the CC value
that occurs in the middle of a run. This setting means that an
event at the meter level changed the CC before the run finished
and another run must be performed to achieve a more accurate
value. The certainty in this case is high, >50,000 ppm.
Figure 39 to Figure 41 show the speed of convergence of the mSure
result (the CC value). As the value of the shunt increases, or as the
gain of the PGA increases, the speed of convergence also increases
due to the signal size being larger. These are both parameters
that must be set based on the overall system, taking into account
factors such as the maximum current being measured. Figure 39
to Figure 41 show how the speed of convergence is influenced
from factors in a system.
300µΩ
500µΩ
1000µΩ
2000µΩ
0 20406080100120
CALIBRATION TIME TO REACH ACCURACY (Seconds)
140 150 180 200
1.000
0.800
0.600
0.400
0.353
18.3 21.6 73.2
0.250
0.200
0
ABSOLUTE ACCURACY TARGET (%)
16519-039
Figure 39. Speed of Convergence for Autocalibration (Shunt Channel,
Normal Mode) Based on Shunt Value
300µΩ
500µΩ
1000µΩ
2000µΩ
0 1020304050
CALIBRATION TIME TO REACH ACCURACY (Seconds)
60 70 80 90
0.600
0.353
0.500
0.400
0.250
0.300
0.200
0.100
0
ACCURAC Y TARGET (%)
8 22.1 26.9 74.7
16519-240
Figure 40. Speed of Convergence for Autocalibration (Shunt Channel, Turbo
Mode) Based on Shunt Value
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