Programmable Single Phase Energy Metering
IC with Tamper Detection
SA2007P
FEATURES
+
Provides direct interface to mechanical counters
+
Calibration and setup stored on external EEPROM - no
+
+
+
trimpots required
Monitors both Live and Neutral for tamper detection
Flexible programmable features
Meets the IEC 521/1036 Specification for Class 1 AC Watt
hour meters
sames
+
+
+
+
+
Total power consumption rating below 50mW
Adaptable to different types of sensors
Operates over a wide temperature range
Precision voltage reference on-chip
Precision oscillator on chip
DESCRIPTION
The SAMES SA2007P is a single phase bi-directional energy
metering integrated circuit. It provides a cost effective solution
for energy meters with electro-mechanical displays, such as
stepper motors and impulse counters. A precision oscillator,
that replaces an external crystal is integrated on chip.
Two current sensor inputs allow the measurement of energy
consumption on both the live and neutral lines.
Direction detection of energy flow as well as other common
tamper conditions are flagged.
The power consumption on both the live and neutral are
continuously measured and the larger of the two is selected for
energy metering.
The SA2007P drives the calibration LED, the indicator LEDs
and the electro-mechanical counter directly.
The SA2007P does not require any external trim-pots. All
required calibration and configuration data is read from a small
external EEPROM.
The SA2007P integrated circuit is available in 20 pin dual-in-
line plastic (DIP-20) and small outline (SOIC-20) package
types.
VDD VSS
IIN1
IIP1
IIN2
IIP2
IVP
GND
ANALOG
SIGNAL
PROCESSING
AND
POWER
CALCULATION
POWER 1 (DIGITAL)
ELT
POWER 2 (DIGITAL)
COM-
PARATOR
SEL1
VOLTAGE
REF.
OSC
IIC
BUS
INTERFACE
POWER
TO
PULSE
RATE
DIRO
LED
MOP
MON
Dr-01594
VREF
TCLK
SCL SDA RLOAD
TEST
Figure 1: Block diagram
SPEC-0074 (REV. 2)
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PRELIMINARY
16-01-01
SA2007P
ELECTRICAL CHARACTERISTICS
(V
DD
= 2.5V, V
SS
= -2.5V, over the temperature range -10°C to +70°C
#
, unless otherwise specified.)
Parameter
Operating temp. Range
Supply Voltage: Positive
Supply Voltage: Negative
Supply Current: Positive
Supply Current: Negative
Current Sensor Inputs (Differential)
Input Current Range
Voltage Sensor Input (Asymmetrical)
Input Current Range
Pin VREF
Ref. Current
Ref. Voltage
Digital I/O
Pins RLOAD, TCLK, TEST, SEL1,
ELT, SDA
Input High Voltage
Input Low Voltage
Pins MOP, MON, LED, SCL, DIRO
Output High Voltage
Output Low Voltage
Pin SDA
Pull up current
Pins TEST, RLOAD, TCLK
Pull down current
I
IV
-I
R
V
R
-25
45
1.1
50
1.2
+25
55
1.3
µA
µA
V
I
II
-25
+25
µA
Symbol
T
O
V
DD
V
SS
I
DD
I
SS
Min
-25
2.25
-2.75
4.7
4.7
6.6
6.6
Typ
Max
+85
2.75
-2.25
9.4
9.4
Unit
°C
V
V
mA
mA
sames
Condition
Peak value
Peak value
With R = 24kW
connected to V
SS
Reference to V
SS
V
IH
V
IL
V
OH
V
OL
-I
IL
V
DD
-1
V
SS
+1
V
V
V
V
µA
I
OH
= -2mA
I
OL
= 5mA
V
I
= V
SS
V
DD
-1
V
SS
+1
54
24
I
IH
48
110
µA
V
I
= V
DD
# Extended Operating Temperature Range available on request.
ABSOLUTE MAXIMUM RATINGS*
Parameter
Supply Voltage
Current on any pin
Storage Temperature
Operating Temperature
Symbol
V
DD
-V
SS
I
PIN
T
STG
T
O
Min
-0.3
-150
-40
-40
Max
6.0
+150
+125
+85
Unit
V
mA
°C
°C
*Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress
rating only. Functional operation of the device at these or any other condition above those indicated in the operational sections of
this specification, is not implied. Exposure to Absolute Maximum Ratings for extended periods may affect device reliability.
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PRELIMINARY
SA2007P
PIN DESCRIPTION
PIN
20
8
Designation
GND
V
DD
Description
Analog Ground. The voltage to this pin should be mid-way between V
DD
and V
SS
.
sames
Positive supply voltage. The voltage to this pin is typically +2.5V if a shunt resistor is used for
current sensing or in the case of a current transformer a +5V supply can be applied.
Negative supply voltage. The voltage to this pin is typically -2.5V if a shunt resistor is used for
current sensing or in the case of a current transformer a 0V supply can be applied.
The current into the A/D converter should be set at 14µA
RMS
at nominal mains voltage. The voltage
sense input saturates at an input current of ±25µA peak.
Inputs for current sensor - channel 1 and channel 2. The shunt resistor voltage from each channel
is converted to a current of 16µA
RMS
at rated conditions. The current sense input saturates at an
input current of ±25µA peak.
This pin provides the connection for the reference current setting resistor. A 24kW resistor
connected to V
SS
sets the optimum operating condition.
Serial clock output. This output is used to strobe data from the external EEPROM.
Serial data. Send and receive data from an external EEPROM.
Motor pulse outputs. These outputs can be used to drive an impulse counter or stepper motor directly.
Calibration LED output. Refer to section Led Output (LED) for the pulse rate output options.
Configuration reload input. A falling edge will trigger a register reload from the external EEPROM.
Current channel select output. This output indicates which channel is been used for kWh metering.
Earth loop tamper output. This output indicates an earth loop tamper condition.
Direction output. This output indicates the energy flow direction
Test input. Connect to V
SS
for normal operation.
14
V
SS
19
IVP
1, 2,
3, 4
IIN1, IIP1
IIN2, IIP2
5
VREF
6
7
9, 12
13
15
16
17
18
SCL
SDA
MON, MOP
LED
RLOAD
SEL1
ELT
DIRO
10, 11 TEST, TCLK
ORDERING INFORMATION
IIN1
IIP1
IIN2
IIP2
VREF
SCL
SDA
VDD
MON
TEST
1
2
3
4
5
6
7
8
9
10
20
19
GND
IVP
Part Number
SA2007PPA
SA2007PSA
Package
DIP-20
SOIC-20
18 DIRO
17 ELT
16
15
SEL1
RLOAD
14 VSS
13
12
11
LED
MOP
TCLK
DR-01595
Figure 2: Pin connections: Package: DIP-20, SOIC-20
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PRELIMINARY
SA2007P
FUNCTIONAL DESCRIPTION
The SA2007P 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
single 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 SA2007P 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 SA2007P
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. The
metering of energy consumption is taken from the source,
which shows the higher consumption.
Various pulse outputs (MOP MON and LED) are available.
,
The pulse rate on these pins follows the 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
.
The SA2007P configures itself from an external low cost
EEPROM that contain all meter configurations and calibration
data. No external trimming is required for this device.
Calibration of the meter may be fully automated.
POWER CALCULATION
In Figure 7, the voltage drops across the current transformers
terminating resistors are converted to currents for each
current sense input, by means of resistors R
10
and R
11
(channel
1) as well as R
12
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 R
7
(1MW).
See Device Configuration for more details on the processing of
measured energy to frequency outputs.
GND
DR-01288
sames
ANALOG INPUT CONFIGURATION
The input circuitry of the current and voltage sensor inputs are
illustrated in figure 3. 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.
AUTOMATIC DEVICE CONFIGURATION (BOOT UP)
During power up, registers containing configuration and
calibration information are updated from an external
EEPROM. The device itself never writes to the EEPROM so
any write protect features offered by manufacturer of
EEPROM's may be used to protect the configuration and
calibration data of the meter. The device reloads its
configuration every 1193 seconds from the external EEPROM
in order to ensure correct operation of the meter. Every data
byte stored in the EEPROM is protected with a checksum byte
to ensure data integrity.
ELECTROSTATIC DISCHARGE (ESD)
PROTECTION
The SA2007P integrated circuit's input's/outputs are protected
against ESD.
POWER CONSUMPTION
The power consumption rating of the SA2007P integrated
circuit is less than 30mW.
V DD
IIP
CURRENT
SENSOR
INPUTS
VSS
VDD
A
I
IIN
VSS
VDD
IVP
VOLTAGE
SENSOR
INPUT
V SS
A
V
Figure 3: Analog input internal configuration
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PRELIMINARY
SA2007P
INPUT SIGNALS
VREF
A bias resistor of 24kW set optimum bias and reference
conditions on chip. Calibration of the SA2007P should be done
as described in the Device Configuration section.
sames
Selected Input Indicator (SEL1)
The SA2007P continuously compares the power
consumptions on current channel 1 inputs and current channel
2 inputs. The larger of the two measurements is used for
metering. The SEL1 output pin indicates which channel is
currently being used for the pulse output.
Signal
Output
SEL 1
Value
0
1
Description
Channel 1 selected (IIN1/IIP1)
Channel 2 selected (IIN2/IIP2)
Serial Data (SDA)
The SDA pin connects directly to the SDA pin of an external
EEPROM. The pin is used to transfer data between the
EEPROM to the SA2007P. An external pull up resistor in not
needed.
Serial Clock (SCL)
The SCL pin connects directly to the SCL pin of an external
EEPROM. The SCL output is used to strobe data at a rate of
50kHz out of the EEPROM. An external pull up resistor in not
needed.
Switching between channels will not be faster than once per
second in case both channels are balanced.
Earth Loop Tamper Indication (ELT)
In case the power measurements from both current channels
differ by more than 12.5%, (indicating a earth loop tamper
condition), the ELT output is set to zero. The SA2007P
continues to generate output pulses from the larger of the two
measured powers in this condition. The ELT output is active low.
Configuration Reload (RLOAD)
A falling edge on the RLOAD pin, will trigger a register update
from the external EEPROM. This feature may be used during
calibration to load updated register data in the SA2007P. For
normal operation of the SA2007P the RLOAD pin may be left
floating.
Direction Indication (DIRO)
The SA2007P provides information about the energy flow
direction of both current channels on pin DIRO .
A logic 1 on pin DIRO indicates reverse energy flow of both
current channels. Reverse energy flow is defined as the
condition where the voltage sense input and current sense
input are out of phase (greater than 90 degrees). Positive
energy flow, when voltage sense and both current sense input
are in phase, is indicated on pin DIRO as a logic 0.
The DIRO output will toggle between 1 and 0 a rate of 1Hz in
case one of the current channels measure positive energy and
the other negative energy. The condition may accure with a
improper installed or tampered meter.
The DIRO pin may be used to drive a LED in order to indicate
reverse energy.
Signal
Description
Output Value
1
DIRO
0
1Hz
Reverse energy flow
Forward energy flow
Out of phase current channels
OUTPUT SIGNALS
Motor output (MOP, MON)
The motor pulse width is programmable for 71ms and 142ms.
The MON pulse will follow the MOP pulse within the selected
pulse width time. This prevents that the motor armature is in
the wrong position after a power failure. Both MOP and MON
outputs are active high. One energy pulse is represented by a
MOP pulse followed by a MON pulse. The motor drive wave
forms are shown in figure 4.
LED output (LED)
Three options for the LED output pulse rate are available, 6400
and 3200 pulses per kWh, as well as a pulse rate of 1252
pulses per second at rated conditions. At 1252 pulse per
second t
LED
is 71µs, for the other options t
LED
is 10ms. The LED
output is active low as in figure 5.
An integrated anti-creep function prevents any output pulses if
the measured power is less than 0.02% of the meters rated
current.
VDD
MOP
VSS
VDD
MON
VSS
DR-01559
VDD
LED
VSS
t
m
t
m
t
m
DR-01332
t
LED
Figure 4: Motor drive on MON and MOP pins
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Figure 5: LED pulse output
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PRELIMINARY
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