Single Phase Power/Energy Metering IC with
Tamper Detection
SA2007M
FEATURES
+
Provides direct interface to mechanical counters
+
Monitors Live and Neutral for tamper detection
+
Performs bidirectional energy measurement
+
Various setup modes selectable
+
Meets the IEC 521/1036 Specification for Class 1 AC Watt
hour meters
sames
+
+
+
+
+
Total power consumption rating below 30mW
Adaptable to different types of sensors
Operates over a wide temperature range
Precision voltage reference on-chip
Precision oscillator on chip
DESCRIPTION
The SAMES SA2007M is a single-phase bidirectional energy
metering integrated circuit. It provides a mono-chip 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.
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 SA2007M drives the calibration LED, the indicator LEDs
and the electro-mechanical counter directly.
The SA2007M integrated circuit is available in 20 pin dual-in-
line plastic (DIP-20) and small outline (SOIC-20) package
types.
VDD VSS
IIN1
IIP1
ANALOG
SIGNAL
PRO-
CESSING
AND
POWER
CAL-
CULATION
POWER 1 (DIGITAL)
ELT
POWER 2 (DIGITAL)
COM-
PARATOR
SEL1
IIN2
IIP2
IVP
GND
DIRO
VOLTAGE
REF.
POWER
TO
PULSE RATE
LED
MOP
MON
OSC
Dr-01558
VREF
TCLK
MP1 MP0
RATED
Figure 1: Block diagram
SPEC-0075 (REV. 2)
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PRELIMINARY
16-01-01
SA2007M
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 DIRO, LED, MON, MOP
Output High Voltage
Output Low Voltage
Pins MP0, MP1, TCLK, RATED,
SEL1, ELT
Input High Voltage
Input Low Voltage
Pin RATED
Pin scan current**
Pins MP0, MP1, TCLK
Pull down current
V
OH
V
OL
V
DD
-1
V
SS
+1
V
V
I
IV
-I
R
V
R
-25
45
1.1
50
+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
4.1
4.1
5.8
5.8
Typ
Max
+85
2.75
-2.25
8.2
8.2
Unit
°C
V
V
mA
mA
sames
Condition
Peak value
Peak value
With R = 24kW
connected to V
SS
Reference to V
SS
I
OH
= -2mA
I
OL
= 5mA
V
IH
V
IL
I
IH
-I
IL
I
IH
V
DD
-1
3.1
2
48
V
SS
+1
7
4.6
110
V
V
mA
mA
µA
V
I
= V
DD
V
I
= V
SS
V
I
= V
DD
#Extended Operating Temperature Range available on request.
** Switched to pin-scan mode every 1.1 seconds for 71µs.
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
-25
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
SA2007M
PIN DESCRIPTION
PIN
20
8
Designation
GND
V
DD
Description
sames
Analog Ground. The voltage to this pin should be mid-way between V
DD
and V
SS
.
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.
Motor pulse rate select inputs. Described under Input Signals.
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.
Rated condition select input. Described under Input Signals.
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.
No Connection.
Test input. Connect to V
SS
for normal operation.
14
19
V
SS
IVP
1, 2,
3, 4
IIN1, IIP1
IIN2, IIP2
5
6, 7
9, 12
13
15
16
17
18
11
10
VREF
MP0, MP1
MON, MOP
LED
RATED
SEL1
ELT
DIRO
NC
TCLK
ORDERING INFORMATION
IIN1
IIP1
IIN2
IIP2
VREF
MP1
MP0
VDD
MON
TCLK
1
2
3
4
5
6
7
8
9
10
20
19
GND
IVP
Part Number
SA2007MPA
SA2007MSA
Package
DIP-20
SOIC-20
18 DIRO
17 ELT
16
15
SEL1
RATED
14 VSS
13
12
11
LED
MOP
NC
DR-01595
Figure 2: Pin connections: Package: DIP-20, SOIC-20
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PRELIMINARY
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 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).
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.
IVP
VOLTAGE
SENSOR
INPUT
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.
V DD
IIP
CURRENT
SENSOR
INPUTS
VSS
VDD
A
I
IIN
VSS
VDD
V SS
A
V
GND
DR-01288
Figure 3: Analog input internal configuration
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PRELIMINARY
SA2007M
INPUT SIGNALS
VREF
A bias resistor of 24kW sets optimum bias and reference
conditions on chip. Calibration of the SA2007M should be
done on the voltage input as described in Typical Application.
sames
OUTPUT SIGNALS
Motor output (MOP, MON)
The MON pulse will follow the MOP pulse within 142ms. This
prevents that the motor armature is in the wrong position after a
power failure. Both MOP and MON outputs are active high.
The motor drive wave forms are shown below:
VDD
MOP
VSS
VDD
Motor pulse rate select (MP1 and MP0)
The pulse rate of the motor driver output of the SA2007M is
selected by the inputs MP1 and MP0. Three pulses rate
options are available as shown in the following table:
Pulse rate selection
Pulse Rate
Selection Input
MP1
V
SS
V
SS
V
DD
V
DD
MP0
V
SS
V
DD
V
SS
V
DD
Motor drive
output
selection
1
10
100
Device test mode
MON
Unit
pulses/kWh
pulses/kWh
pulses/kWh
VSS
DR-01559
t
m
t
m
t
m
t
m
= 142ms
Figure 4: Motor drive on MON and MOP pins
LED output (LED)
The LED output pulse at a fixed rate of 6400 pulses per kWh.
The LED output is active low. The LED waveform is shown
below:
Please note that the device will not perform metering functions
as described in this document while in test mode.
Rated condition select (RATED)
The rated condition select pin gives the option of having a 3:2:1
scaling ratio for the rated meter current. This feature is
particularly useful in circumstances where a manufacturer
requires a meter for use in a system rated for two different
conditions, for example 230V/60A and 230V40A. With the
rated condition select the SA2007M allow for the development
of different rated meters requiring minimal changes. The
following table below lists the option available (assuming the
rated condition to be 230V/60A).
LED
VDD
VSS
DR-01332
t
LED
Figure 5: LED pulse output
An integrated anti-creep function prevents any output pulses if
the measured power is less than 0.02% of the meters rated
current.
Rated condition select (RATED)
Signal Input RATED
V
SS
OPEN
V
DD
Rated Conditions
230V / 20A
230V / 40A
230V / 60A
Selected input indicator (SEL1)
The SA2007M continuously compares the power
consumptions on current channel 1 inputs and current channel
2 inputs. The larger of the two measurements are used for
metering. The SEL1 output pin indicates which channel is
currently being used for the pulse output.
Signal
Output
SEL 1
1
Channel 2 selected (IIN2/IIP2)
Value
0
Description
Channel 1 selected (IIN1/IIP1)
Switching between channels will not be faster than once per
second when both channels are balanced.
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PRELIMINARY
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