MAXQ3183-RAN+ Maxim Integrated Products, MAXQ3183-RAN+ Datasheet - Page 71

• Manufacturer Part Number: MAXQ3183-RAN+
• Description: IC AFE POLYPHASE MULTI 28TSSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAXQ3183-RAN+

• Number Of Channels: 8
• Power (watts): 140mW
• Voltage - Supply, Analog: 3.6V
• Voltage - Supply, Digital: 3.6V
• Package / Case: 28-TSSOP
• For Use With: MAXQ3183-KIT - KIT EV REFRNC DSIGN FOR MAXQ3183
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Number Of Bits: -
• Other names: 90-M3183+RAN

This mode enables a subset of metering functions while
operating from the lower frequency internal RC oscilla-
tor to conserve power. The actual system clock fre-
quency used is the RC oscillator output frequency
divided by 8, which results in a system clock frequency
of approximately 1MHz.
The parameters provided in the LOWPM are:
• Voltage RMS
• Current RMS
• Ampere-Hour
The ampere-hour value is readable from the X.ESF reg-
isters (X = A/B/C). Entry to LOWPM mode only occurs
at the request of the master. The master must set the
LOWPM_E bit (register address 0xC03) to 1 to place
the MAXQ3183 into LOWPM mode. Entering LOWPM
mode changes the clock frequency, thereby invalidat-
ing a number of configuration registers. As a result, the
master must immediately reload the configuration regis-
ters and filter with new, updated values before metering
measurement operations can continue.
The master instructs the MAXQ3183 to exit LOWPM
mode by reading the LOWPM_X bit (register address
0xC04).
The MAXQ3183 contains a temperature sensor that can
be used by host software for any purpose, including
compensating power readings for temperature effects.
Use the virtual register command (TEMP_C, address
0xC01) to perform a temperature conversion. The
MAXQ3183 returns the value in degrees Celsius, with a
resolution of 1°C. Internally, the MAXQ3183 performs a
temperature sensor read and scales the sensor output
by the TEMP_CC (address 0x060) coefficient to provide
an output in degrees Celsius. The conversion formula is:
Where RAW_TEMP is raw digitized temperature sensor
output that is proportional to absolute temperature.
Conversion coefficient TEMP_CC must be calibrated
and set by the host; the default value is 0x0000.
Ideal hardware should produce a current reading lin-
early proportional to the input current. However, due to
noise or other factors, the RMS current read by the
meter might not be precisely linear. The current offset
Low-Power Measurement Mode (LOWPM)
TEMP_C = RAW_TEMP x TEMP_CC/2
Low-Power, Multifunction, Polyphase AFE
______________________________________________________________________________________
Advanced Calibrations
Calibrating Current Offset
with Harmonics and Tamper Detect
Temperature
16
- 273.15
(X.OFFS_HI, X = A/B/C) can be used to compensate
the current channel nonlinearity.
Since the MAXQ3183 tracks the input current to deter-
mine what linearity compensation factors to use, the
user must choose two points (i
above the low current threshold, and get the X.IRMS
current readings (r
cept of the line drawn between the two points, that is,
the offset. To calculate the value for the offset register,
use the following formula:
In this equation, i
the current reading, respectively, in meter units at the
higher of the two reference currents; i
applied current and the current reading, respectively, in
meter units at the lower of the two reference currents.
The gain (X.I_GAIN) may require recalibration after the
offset register updated.
The current channel includes a variable-gain amplifier
that introduces a gain of 32 when the current falls
below the low current threshold (about 1/32 of full-scale
current I
be controlled with arbitrary precision, and because
high gain implies increased noise, it may be necessary
to calibrate the MAXQ3183 to maintain linearity at the
lowest inputs.
There are two settings that manage low-current lineari-
ty: an offset setting, OFFS_LO; and a gain setting,
GAIN_LO. Setting the offset is simple. Ensure no cur-
rent is flowing in the current circuit. Read X.IRMS. To
calculate offset use following formula:
Program the offs into the OFFS_LO register.
So, if the user reads 0x0113 from the X.IRMS register,
program 0xFEED into the X.OFFS_LO register. Setting
the X.GAIN_LO register means applying a current below
the low-current threshold, reading the value from the
MAXQ3183, and adjusting the gain accordingly. Note
that the low-end gain is applied in addition to the overall
gain provided in the X.I_GAIN register.
Apply a known current with peak value less than the
low-current threshold. Ensure that there is no previous
value in the low-current gain register, A.GAIN_LO, by
FS
). Because the gain of the amplifier cannot
hi
lo
offs
and r
offs = -X.IRMS
and r
=
r i
2
hi
hi lo
hi
4
). Then calculate the Y-inter-
are the applied current and
(
i
lo
−
−
i r
lo
hi lo
i
Calibrating Linearity
hi
and i
)
lo
hi
and r
) comfortably
lo
are the
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