Single Phase Power/Energy Metering IC with
Tamper Detection
sames
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
+
+
+
+
+
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
hour meters
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.
The power consumption on both the live and neutral are
continuously measured and the larger of the two is selected for
energy metering.
Two current sensor inputs allow the measurement of energy
consumption on both the live and neutral.
The SA2007M integrated circuit is available in 20 pin dual-inline plastic (DIP-20) and small outline (SOIC-20) package
types.
Direction detection of energy flow as well as other common
tamper conditions are flagged.
The SA2007M drives the calibration LED, the indicator LEDs
and the electro-mechanical counter directly.
VDD VSS
POWER 1 (DIGITAL)
IIN1
IIP1
ANALOG
SIGNAL
PROCESSING
AND
POWER
CALCULATION
IIN2
IIP2
IVP
ELT
COMPARATOR
POWER 2 (DIGITAL)
SEL1
GND
DIRO
Dr-01558
VOLTAGE
REF.
OSC
VREF
TCLK
POWER
TO
PULSE RATE
LED
MOP
MON
MP1 MP0
RATED
Figure 1: Block diagram
SPEC-0075 (REV. 2)
1/10
PRELIMINARY
16-01-01
sames
SA2007M
ELECTRICAL CHARACTERISTICS
(VDD = 2.5V, VSS = -2.5V, over the temperature range -10°C to +70°C#, unless otherwise specified.)
Symbol
Min
Operating temp. Range
TO
Supply Voltage: Positive
Typ
Max
Unit
-25
+85
°C
VDD
2.25
2.75
V
Supply Voltage: Negative
VSS
-2.75
-2.25
V
Supply Current: Positive
IDD
4.1
5.8
8.2
mA
Supply Current: Negative
ISS
4.1
5.8
8.2
mA
Parameter
Condition
Current Sensor Inputs (Differential)
Input Current Range
III
-25
+25
µA
Peak value
IIV
-25
+25
µA
Peak value
-IR
VR
45
1.1
55
1.3
µA
V
With R = 24kW
connected to VSS
Reference to VSS
Pins DIRO, LED, MON, MOP
Output High Voltage
Output Low Voltage
VOH
VOL
VDD-1
VSS+1
V
V
Pins MP0, MP1, TCLK, RATED,
SEL1, ELT
Input High Voltage
Input Low Voltage
VIH
VIL
VDD-1
VSS+1
V
V
IIH
-IIL
3.1
2
7
4.6
mA
mA
VI = VDD
VI = VSS
IIH
48
110
µA
VI = VDD
Voltage Sensor Input (Asymmetrical)
Input Current Range
Pin VREF
Ref. Current
Ref. Voltage
50
Digital I/O
Pin RATED
Pin scan current**
Pins MP0, MP1, TCLK
Pull down current
IOH = -2mA
IOL = 5mA
#Extended Operating Temperature Range available on request.
** Switched to pin-scan mode every 1.1 seconds for 71µs.
ABSOLUTE MAXIMUM RATINGS*
Parameter
Symbol
Min
Max
Unit
Supply Voltage
VDD -VSS
-0.3
6.0
V
Current on any pin
IPIN
-150
+150
mA
Storage Temperature
TSTG
-40
+125
°C
Operating Temperature
TO
-25
+85
°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.
http://www.sames.co.za
2/10
PRELIMINARY
sames
SA2007M
PIN DESCRIPTION
PIN
Designation
Description
20
GND
8
VDD
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.
14
VSS
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.
19
IVP
The current into the A/D converter should be set at 14µARMS at nominal mains voltage.
The voltage sense input saturates at an input current of ±25µA peak.
1, 2,
3, 4
IIN1, IIP1
IIN2, IIP2
Inputs for current sensor - channel 1 and channel 2. The shunt resistor voltage from each
channel is converted to a current of 16µARMS at rated conditions. The current sense input
saturates at an input current of ±25µA peak.
5
VREF
This pin provides the connection for the reference current setting resistor. A 24kW resistor
connected to VSS sets the optimum operating condition.
6, 7
MP0, MP1
Motor pulse rate select inputs. Described under Input Signals.
9, 12
MON, MOP
Motor pulse outputs. These outputs can be used to drive an impulse counter or stepper motor
directly.
13
LED
15
RATED
16
SEL1
17
ELT
18
DIRO
11
NC
10
TCLK
Analog Ground. The voltage to this pin should be mid-way between VDD and VSS.
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 VSS for normal operation.
ORDERING INFORMATION
IIN1
1
20
GND
IIP1
2
19
IVP
IIN2
3
18 DIRO
IIP2
4
17 ELT
VREF
5
16
SEL1
MP1
6
15
RATED
MP0
7
14 VSS
VDD
8
13
LED
MON
9
12
MOP
TCLK
10
11
NC
Part Number
Package
SA2007MPA
DIP-20
SA2007MSA
SOIC-20
DR-01595
Figure 2: Pin connections: Package: DIP-20, SOIC-20
http://www.sames.co.za
3/10
PRELIMINARY
sames
SA2007M
FUNCTIONAL DESCRIPTION
ANALOG INPUT CONFIGURATION
The input circuitry of the current and voltage sensor inputs are
illustrated below.
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.
These inputs are protected against electrostatic discharge
through clamping diodes.
The integrated circuit includes all the required functions for 1phase 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.
The feedback loops from the outputs of the amplifiers AI and AV
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.
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 VSS.
V DD
IIP
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 R13. (channel 2). The current sense input
saturates at an input current of ±25µA peak.
CURRENT
SENSOR
INPUTS
VSS
AI
VDD
IIN
The mains voltage (230VAC) is divided down through a divider
to 14VRMS. The current into the A/D converter input is set at
14µARMS at nominal mains voltage, via resistor R7 (1MW).
VSS
VDD
IVP
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.
VOLTAGE
SENSOR
INPUT
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.
DR-01288
V SS
AV
GND
Figure 3: Analog input internal configuration
http://www.sames.co.za
4/10
PRELIMINARY
sames
SA2007M
INPUT SIGNALS
OUTPUT SIGNALS
VREF
Motor output (MOP, MON)
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.
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:
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:
VDD
MOP
VSS
Pulse rate selection
VDD
Pulse Rate
Selection Input
MON
MP1
MP0
Motor drive
output
selection
VSS
VSS
1
pulses/kWh
VSS
VDD
10
pulses/kWh
VDD
VSS
100
pulses/kWh
VDD
VDD
Device test mode
Unit
VSS
tm
tm
tm
tm = 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)
VDD
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
VSS
tLED
DR-01332
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.
Selected input indicator (SEL1)
Rated condition select (RATED)
Signal Input RATED
DR-01559
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.
Rated Conditions
VSS
230V / 20A
OPEN
230V / 40A
VDD
230V / 60A
Signal
Output
Description
Value
0
Channel 1 selected (IIN1/IIP1)
1
Channel 2 selected (IIN2/IIP2)
SEL 1
Switching between channels will not be faster than once per
second when both channels are balanced.
http://www.sames.co.za
5/10
PRELIMINARY
sames
SA2007M
Earth loop tamper indication (ELT)
If 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 SA2007M
continues to generate output pulses from the larger of the two
measured powers in this condition. The ELT output is active
low.
Direction indication (DIRO)
The SA2007M 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
when one of the current channels measure positive energy
and the other negative energy. This condition may occur with a
improper installed or tampered meter.
The DIRO pin may be used to drive a LED in order to indicate
reverse energy.
Signal
Output
DIRO
Description
Value
1
Reverse energy flow
0
Forward energy flow
1Hz
Out of phase current channels
http://www.sames.co.za
6/10
PRELIMINARY
sames
SA2007M
TYPICAL APPLICATION
The analog (metering) interface described in this section is
designed for measuring 230V/60A with precision better than
Class 1.
The most important external components for the SA2007M
integrated circuit are the current sense resistors, the voltage
sense resistors and the bias setting resistor. The resistors
used in the metering section should be of the same type so
temperature effects are minimized.
Current Input IIN1, IIP1, IIN2, IIP2
Two current transformers are used to measure the current in
the live and neutral phases. The output of the current
transformer is terminated with a low impedance resistor. The
voltage drop across the termination resistor is converted to a
current that is fed to the differential current inputs of the
SA2007M.
CT Termination Resistor
The voltage drop across the CT termination resistor at rated
current should be at least 20mV. The CTs have low phase shift
and a ratio of 1:2500. The CT is terminated with a 3.6W resistor
giving a voltage drop of 86.4mV across the termination resistor
at rated conditions (Imax for the meter).
The termination resistor on the second current channel is
adjustable by means of P2 to facilitate channel equalization
calibration. The termination resistor is chosen so that a 10W
trimpot in parallel will provide a sufficient channel range.
Current Sensor Input Resistors
The resistors R10, R11 and R12, R13 define the current level
into the current sense inputs of the SA2007M. The resistor
values are selected for an input current of 16µA on the current
inputs of the SA2007M at rated conditions. For a 60A meter at
2500:1 CT the resistor values are calculated as follows:
R10 = R11 = ( IL / 16µA ) x RSH / 2
= 60A / 2500 / 16µA x 3.6W / 2
= 2.7kW
IL = Line current
RSH = CT Termination resistor
2500 = CT ratio
The two current channels are identical so R10 = R11 = R12 =
R13.
at approximately 17µA. At a nominal voltage current of 14µA
allows for 20% overdriving. The mains voltage is divided with a
voltage divider to 14V that is fed to the voltage input pins via a
1MW resistor.
Voltage Divider
The voltage divider is calculated for a voltage drop of 14V.
Equations for the voltage divider are:
RA = R1 + R2 + R3
RB = R7 || (R5 + P1)
A 5k trimpot will be used in the voltage channel for meter
calibration. The center position on the pot is used in the
calibration P1 = 2.5kW.
Combining the two equations gives:
( RA + RB ) / 230V = RB / 14V
Values for resistors R5 = 22kW, P1 = 2.5kW and R7 = 1M W is
chosen.
Substituting the values result in:
RB = 23.9kW
RA = RB x ( 230V / 14V – 1 )
RA = 369kW.
Standard resistor values of R1, R2 and R3 are chosen to be
120kW, 120kW and 130kW.
The capacitor C1 is used to compensate for phase shift
between the voltage sense inputs and the current sense inputs
of the device, in cases where CTs with phase errors are used.
The phase shift caused by the CT may be corrected by
inserting a capacitor in the voltage divider circuit. To
compensate for a phase shift of 0.18 degrees the capacitor
value is calculated as follows:
C = 1 / (2 x p x Mains frequency x R5 x tan (Phase shift angle))
C = 1 / ( 2 x p x 50 x 1MW x tan (0.18 degrees ))
C = 1.013µF
Reference Voltage Bias resistor
R6 defines all on chip and reference currents. With R6 = 24kW
optimum conditions are set. Device calibration is done on the
voltage input of the device.
Voltage Input IVP
The voltage input of the SA2007M (IVP) is driven with a current
of 14µA at nominal mains voltage. The voltage input saturates
http://www.sames.co.za
7/10
PRELIMINARY
SA2007M
http://www.sames.co.za
NEUTRAL
VDD
U1
LIVE
D1
D3
3
Vout
R4
R18
C2
2
L
Vin
GND
1
T1
TZ1
p
+ C5
s
GND
+ C6
R19
D2
P1
D4
C3
GND
8/10
PRELIMINARY
Figure 6: Typical application circuit
R5
VSS
R1
R2
R3
VSS
14V
VDD
C1
LED2
LED3
LED1
LED4
CT2
R8
CT1
R9
P2
1
R11
2
R12
3
R13
4
5
6
R6
7
8
9
C4
10
LIVE
R7
U2
R10
VSS
IIN1
GND
IIP1
IVP
IIN2
DIRO
IIP2
ELT
VREF
SEL1
MP1
RATED
MP0
VSS
VDD
LED
MON
MOP
TCLK
dr-01597
R14
20
R15
R16
R17
19
18
17
16
VDD
15
14
13
VSS
12
11
CNT1
6 5 4 3 2 1 .1
NEUTRAL
sames
sames
SA2007M
Parts List for Application Circuit: Figure 6
Item
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
Symbol
U2
D1
D2
D3
D4
LED1
LED2
LED3
LED4
R1
R2
R3
R4
R5
R6
R7
R8
R9
R10
R11
R12
R13
R14
R15
R16
R17
R18
R19
P1
P2
C1
C2
C3
C4
C5
C6
CT1
CT2
T1
U1
CNT1
TZ1
Detail
DIP-20/SOIC-20
Description
SA2007M
Diode, Silicon 1N4148
Diode, Silicon 1N4148
Diode, Silicon 1N4148
Diode, Silicon 1N4148
or Similar
or Similar
or Similar
or Similar
Light emitting diode, Amber
Light emitting diode, Green
Light emitting diode, Red
Light emitting diode, Green
Resistor, 120k, 1/4W, 1%, metal
Resistor, 120k, 1/4W, 1%, metal
Resistor, 130k, 1/4W, 1%, metal
Resistor, 10W, 2W, Wire wound
Resistor, 24k, 1/4W, 1%, metal
Resistor, 22k, 1/4W, 1%, metal
Resistor, 1M, 1/4W, 1%, metal
Resistor, 1/4W, 1%, metal
Resistor, 1/4W, 1%, metal
Resistor, 1/4W, 1%, metal
Resistor, 1/4W, 1%, metal
Resistor, 1/4W, 1%, metal
Resistor, 1/4W, 1%, metal
Resistor, 1k, 1/4W, 5%
Resistor, 1k, 1/4W, 5%
Resistor, 1k, 1/4W, 5%
Resistor, 1k, 1/4W, 5%
Resistor, 1k, 1/4W, 5%, metal
Resistor, 1k, 1/4W, 5%, metal
Multi-turn, Trim pot, 10k
Multi-turn, Trim pot, 10W
Capacitor
Capacitor, 220nF
Capacitor, 220nF
Capacitor, 820nF
Capacitor, 2200µF, 25V, electrolytic
Note 2
Note 2
Note 1
Note 1
Note 1
Note 1
Note 2
Note 4
Note 3
Capacitor, 100µF, 16V, electrolytic
Current Transformer
Current Transformer
Transformer, 230V/9V
78LC05, Voltage regulator
Bipolar step motor
400V, Metal oxide varistor
Note 1: Resistor (R10, R11, R12 and R13) values are dependent upon the selected value of R8 and R9
Note 2: See TYPICAL APPLICATION when selected the value of R8 and R9.
Note 3: Capacitor (C4) to be positioned as closed to Supply Pins (VDD & VSS) of U-1, as possible.
Note 4: Capacitor (C1) selected to minimize phase error introduced by current transformer (typically 1.5µF for normal CTs)
http://www.sames.co.za
9/10
PRELIMINARY
sames
PM9607AP
SA2007P
DISCLAIMER:
The information contained in this document is confidential and proprietary to South African Micro-Electronic Systems (Pty) Ltd
("SAMES") and may not be copied or disclosed to a third party, in whole or in part, without the express written consent of SAMES. The
information contained herein is current as of the date of publication; however, delivery of this document shall not under any
circumstances create any implication that the information contained herein is correct as of any time subsequent to such date.
SAMES does not undertake to inform any recipient of this document of any changes in the information contained herein, and SAMES
expressly reserves the right to make changes in such information, without notification, even if such changes would render
information contained herein inaccurate or incomplete. SAMES makes no representation or warranty that any circuit designed by
reference to the information contained herein, will function without errors and as intended by the designer.
Any sales or technical questions may be posted to our e-mail address below:
[email protected]
For the latest updates on datasheets, please visit our web site:
http://www.sames.co.za.
SOUTH AFRICAN MICRO-ELECTRONIC SYSTEMS
DIVISION OF LABAT TECHNOLOGIES (PTY) LTD
Tel: (012) 333-6021
Tel: Int +27 12 333-6021
Fax: (012) 333-8071
Fax: Int +27 12 333-8071
33 ELAND STREET
KOEDOESPOORT INDUSTRIAL AREA
PRETORIA
REPUBLIC OF SOUTH AFRICA
P O BOX 15888
33 ELAND STREET
LYNN EAST 0039
REPUBLIC OF SOUTH AFRICA
http://www.sames.co.za
10/10
PRELIMINARY