MAXQ3183-RAN+ Maxim Integrated Products, MAXQ3183-RAN+ Datasheet - Page 67

• 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

• Take the inverse tangent of this value. You get -0.5°;
• Subtract the UUT phase offset from the reference
• Multiply this value by 65,536. The result is 572
• Because the phase correction is toward the capaci-
At this point, the meter is compensated for a single
phase offset. If the phase offset were perfectly flat over
all current levels, that would be sufficient (and for many
current sensors, particularly current shunts, one point is
usually good enough.)
The MAXQ3183 has all the internal circuitry that is
needed for a sophisticated electricity meter, but specif-
ic external hardware is required when configuring the
meter for a particular application. The most critical
decision that must be made is how the load will be con-
nected to the power source, and how the meter will be
connected to measure power consumed in the load.
This section covers how to select hardware compo-
nents for a MAXQ3183 electricity meter.
Generally, three-phase power as delivered from the util-
ity consists of four wires: three voltage phases and a
neutral wire. In one typical three-phase delivery system,
measuring from neutral to any phase would read 120V,
while measuring from any phase to any other phase
would read 208V. Connecting a load so that load cur-
rent is taken from phase lines and returned to neutral is
called a wye-connected load. Connecting a load so
that load current is provided by one phase and
returned on another phase is called a delta-connected
load. The MAXQ3183 can measure power consumed in
either a wye-connected or a delta-connected load.
If the load is connected in a wye fashion, the voltage is
measured from the neutral lead to each of the phases,
and the current measuring device is placed in series
with the load, most often in the hot lead. The sensor is
not placed in the neutral lead to prevent a customer
from defrauding the utility by returning the current to
ground rather than neutral. A current sensor placed in
the hot lead makes fraud even more difficult.
that is, 0.5° capacitive.
meter phase offset. In this case, the phase needs to
move 1° toward the capacitive. Convert this value to
radians: 1° x π/180° = 0.0175 radians.
(0x023C).
tive, the value must be complemented. The two’s
complement of 0x023C is 0xFDC4. This is the value
that should be written to the PA0 phase compensa-
tion register.
Interfacing the MAXQ3183 to
Connections to the Power Source
Low-Power, Multifunction, Polyphase AFE
______________________________________________________________________________________
External Hardware
with Harmonics and Tamper Detect
A delta-connected load can have current measured in
two possible ways. If it is primarily desirable to know
how much power is delivered to the load, one can place
the current sensor in the load circuit between two phas-
es. But if it is more important to know how much current
is being drawn from each supply phase, each current
sensor is placed in the line circuit of each single phase.
Most utilities are only concerned with the total amount
of energy being consumed. If individually accounting
for the power delivered by each phase is not a require-
ment, it is not necessary to measure all three voltages.
Instead, knowing only two voltages and the three cur-
rents is all that is necessary to measure total energy
usage.
There are several ways of doing this. In a wye arrange-
ment, one of the phases—usually phase B—–can be
considered the voltage reference point instead of neu-
tral. Then the voltage measurements can be made from
phase A to phase B and from phase C to phase B. By
using some simple arithmetic, the power delivered by
phase A, phase B, and phase C can be calculated
even though only two voltages are available.
A second mechanism is to have a delta-connected
load, but with one leg—usually the BC leg—split into
two equal loads. The point where the load is split is
defined as the reference. In this arrangement, it is only
necessary to know the voltage between phase C and
the split and phase A and the split, since V
Finally, there is the connection arrangement in which
the load is in a delta configuration with the current sen-
sor at each load, but it is still desired to determine how
much current is in each supply branch. The MAXQ3183
supports all of these connection arrangements.
The MAXQ3183 supports a variety of voltage and cur-
rent sense elements. This section describes the proper-
ties of many of these sensing devices.
A voltage-divider is an ideal voltage-sensing element
when there is no need for voltage isolation. Modern
resistors have virtually no parasitic capacitance or
inductance at the frequencies of interest in an electrici-
ty meter and have extremely low variation with tempera-
ture. When selecting resistors for a voltage-divider,
keep the division ratio high enough so that the peak
voltage value cannot exceed the maximum allowable
input voltage. In the MAXQ3183, the peak input voltage
is about 1V; consequently, a divider in the range of
400:1 to 600:1 is ideal.
Sensor Selection
Voltage Sensors
Voltage-Divider
C
= -V
A
.
67