SA2007M Datasheet, PDF (4/10 Pages) Sames – Single Phase Power/Energy Metering IC with Tamper Detection

SA2007M
FUNCTIONAL DESCRIPTION
The SA2007M 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 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
SA2007M incorporates an anti-tamper scheme by
continuously measuring the power consumption on both LIVE
and NEUTRAL lines. A fault is indicated when these
measurements differ by more than 12.5%. The SA2007M
generates pulses with a frequency proportional to the larger of
the two current measurements. The source (LIVE or
NEUTRAL) for these pulses is indicated on the SEL1 pin.
Frequency outputs (MOP, MON and LED) are available. The
pulse rate on these pins follows the instantaneous active
power consumption measured.
A low voltage stepper may be driven directly from the device by
connecting it between the MOP and MON pins, alternatively an
impulse counter may be driven directly by connecting it
between MOP and V_SS.
POWER CALCULATION
In Figure 6, the voltage drops across the current transformers
terminating resistors are converted to currents for each current
sense input, by means of resistors R₁₀ and R₁₁ (channel 1) as
well as R₁₂ and R_13. (channel 2). The current sense input
saturates at an input current of ±25µA peak.
The mains voltage (230VAC) is divided down through a divider
to 14V_RMS. The current into the A/D converter input is set at
14µA_RMS at nominal mains voltage, via resistor R₇(1MW).
Different pulse rates are available at the MOP and MON pins.
The device may be programmed for a 1 pulse/kWh, 10
pulses/kWh or 100 pulses/kWh output, depending on the
status of the motor pulse rate select pins MP0 and MP1.
The LED pulse rate is fixed at 6400 pulses per kWh. Rated
conditions such as 230V/20A, 230V/40A and 230V/60A may
be chosen with the rated pin. This facility allows meter
manufacturers to cater for a wide range of metering
applications with minimal design changes.
sames
ANALOG INPUT CONFIGURATION
The input circuitry of the current and voltage sensor inputs are
illustrated below.
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.
ELECTROSTATIC DISCHARGE (ESD)
PROTECTION
The SA2007M integrated circuit's input's/outputs are protected
against ESD.
POWER CONSUMPTION
The power consumption rating of the SA2007M integrated
circuit is less than 30mW.
VDD
IIP
CURRENT
VSS
SENSOR
INPUTS
VDD
IIN
VSS
VDD
IVP
VOLTAGE
SENSOR
VSS
INPUT
AI
A_V
DR-01288
GND
Figure 3: Analog input internal configuration
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PRELIMINARY