MAXQ3180-RAN+ Maxim Integrated Products, MAXQ3180-RAN+ Datasheet - Page 67

• Manufacturer Part Number: MAXQ3180-RAN+
• Description: IC AFE POLYPHASE MULTI 28-TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAXQ3180-RAN+

• Number Of Channels: 8
• Power (watts): 35mW
• Voltage - Supply, Analog: 3.6V
• Voltage - Supply, Digital: 3.6V
• Package / Case: 28-TSSOP
• For Use With: MAXQ3180-KIT - KIT EV REFRNC DSIGN FOR MAXQ3180
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of Bits: -

• Divide the applied value (in meter unit) by the value
• Multiply the calculated value by 2
When the gain value is programmed, wait for approxi-
mately 2 to 3 seconds, then reread the RMS value from
A.IRMS. Check that the measured value is correct by
comparing A.IRMS against the applied current in meter
unit.
Current Calibration Example
Assume I
of 10A and a maximum current of 60A.
• The meter is calibrated at the base current of 10A.
• Convert the applied current to meter units. This cal-
• Read the A.IRMS register. You read 0x0017DC85.
• Divide the applied current by the current read from the
• Multiply by 2
For this calibration step, it is necessary to have a power
factor meter, capable of measuring phase angle, con-
nected in the same circuit as the MAXQ3180 meter.
Note that calibration can be performed at any precision
power factor setting. We use a pure resistive load (PF =
1.0) load to illustrate the procedure.
• Apply a resistive load to the meter; the current drawn
• Record the phase angle and direction (capacitive or
• Read and record the real and reactive energy from
• Read the X.REA register. If the high-order bit is set,
• Now determine the correction factor: treating capaci-
read from the MAXQ3180. The result should be a
value between 0 and 2. If the value falls outside of
this range, you have probably miscalculated I
gain value to be programmed into A.I_GAIN. Ensure
the most significant bit is 0.
culation gives 10 x 2
0x00190000.
This is 1,563,781 decimal.
meter. The result is 1,638,400/1,563,781 = 1.0477.
this value to the A.I_GAIN register.
by the load should correspond to the base current of
your meter.
inductive) reported on the power factor meter.
the X.ACT and X.REA registers. Divide the reactive
energy by the real energy. This is the tangent of the
power-phase angle.
the power factor reported in the above step is capac-
itive. If the high-order bit is clear, the power factor
reported in the above step is inductive.
tive values as negative and inductive values as posi-
tive, subtract the angle read from the MAXQ3180
FS
is 102.4A and the meter has a base current
Low-Power, Multifunction, Polyphase AFE
14
______________________________________________________________________________________
x 1.0477 = 17,166 = 0x430E. Write
Calibrating Phase Offset
24
/102.4 = 1,638,400 =
14
. The result is the
FS
.
• Multiply the compensation angle (in radians) by
If I1THR and I2THR are left at their default values
(0x0000), then the value in X.PA0 is applied to the full
measurement range. Alternatively, you could write the
same value into X.PA0, X.PA1, and X.PA2. Then the
same compensation is applied through the whole mea-
surement range regardless of the I1THR and I2THR set-
tings. If desired, calibrate for the phase angle at up to
three different current levels to compensate for nonlin-
earity in the current sensor. See the Advanced
Operation section for more information.
Phase Offset Calibration Example
Assume the meter is a 10/60 meter; that is, the base
current is 10A and the maximum rated current is 60A.
I
and 240V.
• Connect the MAXQ3180-based meter under test in
• Apply power to the meter and apply a load of 10A
• Verify that the I1THR, I2THR, A.PA0, A.PA1, and
• Read the power factor on the reference meter. You
• Read the real energy from register A.ACT (0x1D0).
• Read the reactive energy from register A.REA
• Divide the reactive by the active power: -23,104/
Figure 15. Offset Testing Setup
FS
from the angle read from the reference meter. The
result is the compensation angle.
65,536. This is the value to write into X.PA0.
series with a lab grade reference meter. See the con-
figuration below.
resistive.
A.PA2 registers contain zero.
read 1.5° capacitive. This is not unusual. The load
might not be truly resistive or reactance in the test
configuration could be reflected in the measurement.
You read 0x2865D6 (2,646,510 meter units).
(0x1D4). You read 0xFFFFA5C0 (-23,104 meter
units).
2,646,510 = -0.009.
is 102.4A and V
NEUTRAL
LINE
LOAD
FS
is 558.1V. The test point is 10A
METER
V
LAB
V
UNDER
TEST
UNIT
67