Datasheet

MAX71020
Single-Chip Electricity Meter AFE
18Maxim Integrated
Figure 9. Connecting the MAX71020
The analog input pins of the MAX71020 are
designed for sensors with low source imped-
ance. RC filters with resistance or capacitance
values higher than those implemented in the
demo boards must not be used. Refer to the demo board
schematics for complete sensor input circuits and cor-
responding component values. Maxim Integrated does
not recommend the use of ferrites directly at the analog
signal input.
Connecting the MAX71020
Figure 9 shows a typical MAX71020 configuration. The
IAP-IAN current channel may be directly connected to
either a shunt resistor or a CT, while the IBP-IBN chan-
nel is connected to a CT and is therefore isolated. This
configuration implements a single-phase measurement
with tamper-detection using one current sensor to mea-
sure the neutral current. This configuration can also be
used to create a split phase meter (e.g., ANSI Form 2S).
IAP
VA
IBP
XIN
OSCILLATOR/PLL
XOUT
9.8304MHz
GNDA GNDD
LINE
NEUTRAL
LOAD
MUX AND ADC
COMPUTE
ENGINE
POWER-FAULT
COMPARATOR
REGULATOR
CT
POWER SUPPLY
TEMPERATURE
SENSOR
V
REF
RAM
NEUTRAL
IAN
IBN
YPULSE
SPI
INTERFACE
HOST
SHUNT
CT OR
LINE
VB
RESETZ
INTZ
V
3P3A
V
3P3SYS
MAX71020
RESISTOR-
DIVIDER
LINE
NOTE: THIS SYSTEM IS REFERENCED TO LINE VOLTAGE