SA2002E Datasheet, PDF (5/10 Pages) Sames – Single Phase Uni-directional Power / Energy Metering IC with Instantaneous Pulse Output

SA2002E
FUNCTIONAL DESCRIPTION
The SA2002E is a CMOS mixed signal Analog/Digital
integrated circuit, which performs power/energy calculations
across a power range of 1000:1, to an overall accuracy of
better than Class 1.
The integrated circuit includes all the required functions for 1-
phase power and energy measurement such as two
oversampling A/D converters for the voltage and current sense
inputs, power calculation and energy integration. Internal
offsets are eliminated through the use of cancellation
procedures. The SA2002E generates pulses, the frequency of
which is proportional to the measured power consumption.
One frequency output (FOUT) is available. The pulse rate
follows the instantaneous power consumption measured.
POWER CALCULATION
In the application circuit (figure 6), the voltage drop across the
shunt will be between 0 and 16mV_RMS (0 to 80A through a shunt
resistor of 200µW) The voltage is converted to a current of
between 0 and 16uA_RMS, by means of resistors R1 and R2. The
current sense inputs saturates at an input current of ±25µA
peak.
sames
For the voltage sensor input, the mains voltage (230VAC) is
divided down through a divider (R3, R4 and P1) to 14V_RMS. The
current into the A/D converter input is set at 14µA_RMS at nominal
mains voltage, via resistor R5 (1MW). P1 may be varied for
calibration purposes.
In this configuration, with a mains voltage of 230V and a
current of 80A, the output frequency measured on the FOUT
pin is 1160Hz. In this case one pulse on FOUT correspond to
an energy consumption of 18.4kW/1160Hz = 15.86Ws.
ANALOG INPUT CONFIGURATION
The input circuitry of the current and voltage sensor inputs is
illustrated in figure 7. These inputs are protected against
electrostatic discharge through clamping diodes. The
feedback loops from the outputs of the amplifiers A_I and A_V
generate virtual shorts on the signal inputs. Exact duplications
of the input currents are generated for the analog signal
processing circuitry.
VDD
N
Supply
L
GND
VSS
RSH
R1
R2
U1
VDD
IIN
VDD
IIP
R3
R5
IVP
FOUT
Pulse output
R4
GND
GND
VREF VSS
N
SA2002E
R6
P1
L
GND
DR-01584
VSS
Figure 6: Application circuit
VDD
IIP
CURRENT
VSS
SENSOR
INPUTS
VDD
IIN
VSS
VDD
IVP
VOLTAGE
SENSOR
VSS
INPUT
AI
A_V
DR-01148
GND
Figure 7: Internal analog input configuration
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