Three Phase Multifunction Energy Metering IC
with SPI Interface
SA9904B
FEATURES
Meets the IEC 61268 Specification requirements for
Class 2 AC VAR hour meters
Bidirectional active and reactive power/energy
measurement
Protected against ESD
RMS voltage and frequency measurement
Individual Phase information
SPI communication bus
Meets the IEC 61036 Specification requirements for
Class 1 AC Watt hour meters
Total power consumption rating below 60mW
Uses current transformers for current sensing
Operates over a wide temperature range
Precision on-chip voltage reference
Measures AC inputs only
DESCRIPTION
The SA9904B is a three phase bidirectional energy/power
metering integrated circuit that has been designed to
measure active and reactive energy, RMS mains voltage and
mains frequency. The SA9904B has an integrated SPI serial
interface for communication with a microcontroller. Measured
values for active and reactive energy, the mains voltage and
frequency for each phase are accessible through the SPI
interface from 24 bit registers. The SA9904B active and
reactive energy registers are capable of holding at least 52
seconds of accumulated energy at full load. A mains voltage
zero crossover is available on the F50 output.
The SA9904B includes all the required functions for three
phase power and energy measurement such as
oversampling A/D converters for the voltage and current
sense inputs, power calculation and energy integration. This
innovative universal three phase power/energy metering
integrated circuit is ideally suited for energy calculations in
applications such as electricity dispensing systems,
residential metering and factory energy metering and control.
The SA9904B integrated circuit is available in a 20 pin small
outline (SOIC20) RoHS compliant package.
VDD
POWER ON
RESET
IIP1-3
IIN1-3
DIGITAL
OUTPUT
SIGNAL PROCESSING
CURRENT
CHANNEL
ADC
Instantaneous
power
Instantaneous
power
ACTIVE POWER
REACTIVE POWER
REGISTER
REGISTER
90 DEGREE
PHASE SHIFT
FREQUENCY
REGISTER
F50
IVP1-3
AGND
DIGITAL
OUTPUT
VOLTAGE
CHANNEL
ADC
VRMS
CALCULATION
VRMS
REGISTER
REPEATED 3 TIMES, ONCE FOR EACH DEVICE CHANNEL
VOLTAGE REFERENCE
AND
OSCILLATOR
AND
SPI INTERFACE
CURRENT BIASING
TIMING
VREF
OSC1
OSC2
CS
SCK
DI
DO
VSS
Figure 1: Block diagram
SPEC-0447 (REV. 7)
29-09-2017
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