Single Phase Kilowatt-hour Metering IC
sames
SA2102D
FEATURES
+ Meets the IEC
+
+
+
+
+
+
61036 Specification requirements for
Class 1 AC static watt-hour meters for active energy
+
+
Less than 0.5% Error over a dynamic range of 1:1000
The motor drive outputs (MOP, MON) provide the average
power information and can drive an electro-mechanical
counter directly
+
Bi-directional and uni-directional energy measurement
Configurable for different meter ratings
Precision on-chip oscillator (70ppm/°C drift)
Precision on-chip voltage reference (10ppm/°C drift)
On-chip anti-creep function (0.02% of Imax)
Low power consumption (<25mW typical)
LED pulse output for calibration purposes
DESCRIPTION
(IMAX) and nominal voltages (VNOM) without having to change
the stepper motor or impulse counter gear ratio. The LED pulse
output follows the average power consumption measured and
is intended for meter calibration purposes. In fast calibration
mode this output provides a high frequency pulse rate following
the instantaneous power consumption and can be used for fast
calibration or to interface with a microcontroller. The SA2102D
includes an anti-creep feature preventing any creep effects in
the meter. The SA2102D can be configured for positive,
negative or bi-directional energy measurement.
The SAMES SA2102D* is an accurate single phase
power/energy metering integrated circuit providing a singlechip solution for energy meters. Very few external components
are required and has direct drive capability for electro
mechanical counters. The SA2102D does not require an
external crystal. A precision oscillator, which supplies the
circuitry with a stable frequency, is integrated on chip. The
SA2102D metering integrated circuit generates a pulse rate
output, the frequency of which is proportional to the power
consumption. The SA2102D performs the calculation for
active power. The method of calculation takes the power factor
into account.
The SA2102D integrated circuit is pin compatible to the
SA2002D and is available in 20 pin dual-in-line plastic
(PDIP20), as well as 20 pin small outline (SOIC20) package
types.
Programmable inputs allow the meter manufacturer to
configure the SA2102D for different meter maximum currents
VDD
SO
DIRI
DIRO
FAST
POWER ON
RESET
DIGITAL
OUTPUT
IIP
SIGNAL
PROCESSING BLOCK
ADC
Instantaneous
Average
power
Power
INTEGRATION
IIN
IVP
DIVISION
FOR
CALIBRATION
LED OUTPUT
DIGITAL
OUTPUT
LED
R0
ADC
AGND
R1
VOLTAGE REFERENCE
AND
CURRENT BIASING
OSCILLATOR
AND
TIMING
DIVISION
FOR
COUNTER DRIVER
R2
MOTOR
DRIVING
BUFFERS
VREF
VSS
CNF
MON
MOP
Figure 1: Block diagram
* Patents EP0559499, US5396447, PT559499T, ZA9301579, ZA9400273, ZA9702075
SPEC-0510 (REV. 5)
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http://www.sames.co.za
12-02-03
sames
SA2102D
ELECTRICAL CHARACTERISTICS
#
(VDD = 2.5V, VSS = -2.5V, over the temperature range -10°C to +85°C , unless otherwise specified. Refer to Figure 2 Test Circuit for
Electrical Characteristics.)
Symbol
Min
Supply Voltage:
Positive
VDD
Supply Voltage:
Negative
Typ
Max
Unit
2.25
2.75
V
VSS
-2.75
-2.25
V
Supply Current:
Positive
IDD
2.5
3.6
5
mA
Supply Current:
Negative
ISS
2.5
3.6
5
mA
Input Current Range
IIP, IIN
-25
+25
µA
IIP, IIN Offset Voltage
IIP, IIN
-3.1
+3.1
mV
Input Current Range
IVP
-25
+25
µA
Offset Voltage
IVP
-2.5
+2.5
mV
0.95
µA
140
µA
VSS+1
V
V
VSS+1
V
V
ISOURCE = 5mA
ISINK = 5mA
V
V
ISOURCE = 15mA
ISINK = 15mA
Parameter
Condition
General
Inputs
Current Sensor Inputs
(Differential)
Peak value
Voltage Sensor Input
(Asymmetrical)
Peak value
Digital Inputs
DIRI Input leakage
DIRI
Pull down Current
R2, R1, R0, FAST, CNF, SO
IPD
80
R2, R1, R), FAST, CNF, SO
Input High Voltage
Input Low Voltage
VIH
VIL
VDD-1
LED, DIRO
Output High Voltage
Output Low Voltage
VOH
VOL
VDD-1
MON, MOP
Output High Voltage
Output Low Voltage
VOH
VOL
Outputs
Digital Outputs
4.4
0.1
# Extended Operating Temperature Range available on request.
During manufacturing, testing and shipment we take great care to protect our products against potential external
environmental damage such as Electrostatic Discharge (ESD). Although our products have ESD protection circuitry,
permanent damage may occur on products subjected to high-energy electrostatic discharges accumulated on the human
body and test equipment and can discharge without detection. Therefore, proper ESD precautions are recommended to
avoid performance degradation or loss of functionality during product handling.
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ATTENTION!
Electrostatic
sensitive devices.
Requires special
handling.
sames
SA2102D
ELECTRICAL CHARACTERISTICS (continued)
#
(VDD = 2.5V, VSS = -2.5V, over the temperature range -10°C to +85°C , unless otherwise specified. Refer to Figure 2 Test Circuit for
Electrical Characteristics.)
Parameter
Symbol
Min
Typ
Max
Unit
25
27
µA
1.3
V
Condition
Reference Voltage
Input VREF
Ref. Current
-IR
23
Ref. Voltage
VR
1.1
Temperature coefficient
10
ppm/°C
3.73723
MHz
70
ppm/°C
With R = 47KW
connected to VSS
On-chip oscillator
Oscillator frequency
Temperature coefficient
# Extended Operating Temperature Range available on request.
ABSOLUTE MAXIMUM RATINGS*
Symbol
Min
Max
Unit
VDD-VSS
3.6
6
V
Operating temperature limits
Tlimit
-40
+85
°C
Storage Temperature
TSTG
-40
+125
°C
TO
-25
+85
°C
Parameter
Supply Voltage
Specified operating range
*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.
VDD
VDD SO DIRO DIRI
IIN
LED
IIP
IVP
SA2102D
AGND
MOP
MON
VREF
VSS FAST R0 R1 R2
VSS
Figure 2: Test Circuit for Electrical Characteristics
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SA2102D
PIN DESCRIPTION
PIN
Designation
Description
Analog Ground. The supply voltage to this pin should be mid-way between VDD and VSS.
20
AGND
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
Analog Input for Voltage. The current into the voltage sense input IVP should be set at 14µARM Sat
Nominal Mains Voltage(VNOM). The voltage sense input saturates at an input current of ±25µA peak.
1,2
IIN, IIP
Analog input for current. The current into the current sense input IIP pin should be set at 16µARMS
at Maximum Rated Mains Current (IMAX). The current sense input saturates at ±25µA peak.
3
VREF
This pin provides the connection for the reference current setting resistor. A 47kW resistor
connected to VSS sets the optimum operating condition.
6, 5, 4
R0, R1, R2
7
FAST
11
SO
Select Output. When fast mode is selected this input can be used to enable or disable the internal
pulse stability circuitry for the LED output pulses. Refer to the Select Output section.
18
DIRI
Direction select input. This input is used to enable either bi-directional or uni-directional energy
measurement.
17
DIRO
Direction indicator output. This output indicates the energy flow direction.
13
LED
Calibration LED output. Refer to the Rated Condition Select section of the pulse rate output options.
12, 15
MOP, MON
9
CNF
10, 16
NC
Rated Condition Select. These inputs are used for the different rated condition configuration.
Refer to the Rated Condition Select section.
This input is used to select between STANDARD and FAST mode (LED output pulse rate).
Refer to the LED output section.
Motor pulse outputs. These outputs can drive an electromechanical counter directly.
Configure / Test input. For normal operation this pin must be connected to VSS .
No Connection.
IIN
1
20
AGND
IIP
2
19
IVP
VREF
3
18 DIRI
R2
4
17 DIRO
16 NC
R1 5
SA2102D
R0
6
15 MON
FAST
7
14 VSS
VDD 8
13 LED
CNF 9
12
MOP
11 SO
NC 10
Figure 3: Pin connections: Package: PDIP20, SOIC20
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sames
SA2102D
TERMINOLOGY
Bi-directional and Uni-directional measurement
Rated Operating Conditions*
In the bi-directional configuration the LED, MON and MOP
outputs generate pulses at a frequency that is proportional to
the energy measured in both forward and reverse directions.
Set of specified measuring ranges for performance
characteristics and specified operating ranges for influence
quantities, within which the variations or operating errors of a
meter are specified and determined.
In the uni-directional configuration the LED, MOP and MON
outputs generate pulses at a frequency that is proportional to
the energy measured only if the energy flow is in the same
direction as selected by the DIRI pin. No output pulses are
generated for energy flowing counter to the DIRI pin selection.
The DIRI pin can select either positive or negative energy flow.
Positive energy
Positive energy is defined when the phase difference between
the input signals IIP and IVP are less than 90 Degrees.
Negative energy
Negative energy is defined when the phase difference
between the input signals IIP and IVP is greater than 90
degrees (90..270 degrees).
Specified Measuring Range*
Set of values of a measured quantity for which the error of a
meter is intended to lie within specified limits.
Specified Operating Range*
Range of values of a single influence quantity, which forms a
part of the rated operating conditions.
Limit range of operation*
Extreme conditions which an operating meter can withstand
without damage and without degradation of its metrological
characteristics when it is subsequently operated under its rated
operating conditions.
Nominal Mains Voltage (VNOM)
Nominal Mains Voltage (VNOM ) is the voltage specified for the
energy meter at Rated Operating Conditions.
Percentage error*
Percentage error is given by the following formula:
Maximum Rated Mains Current (IMAX)
%Error =
Energy registered by SA2102D - True energy
True energy
X 100
Maximum Rated Mains Current is the current flowing through
the energy meter at Rated Operating Conditions.
Constant*
NOTE Since the true value cannot be determined, it is approximated
by a value with a stated uncertainty that can be traced to standards
agreed upon between manufacturer and user or to national standards.
Value expressing the relation between the active energy
registered by the meter and the corresponding value of the test
output. If this value is a number of pulses, the constant should
be either pulses per kilowatt-hour (imp/kWh) or watt-hours per
pulse (Wh/imp).
*IEC 61036, 2000. Alternating Current Static Watt-hour Meters for Active Energy. Edition 2.1
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sames
SA2102D
PERFORMANCE GRAPHS
VDD
VDD SO DIRO DIRI
R1
IIN
0,1A
to 80A
Rsh
LED
IIP
R2
R3
R5
IVP
SA2102D
AGND
R4
220V
MOP
P1
MON
VREF
VSS FAST R0 R1 R2
R6
VSS
1.5
1.25
1
0.75
0.5
POSITIVE ENERGY
0.25
0
-0.25
NEGATIVE ENERGY
-0.5
-0.75
-1
-1.25
-1.5
0.1
1
IEC MAX
%ERROR
%ERROR
Figure 4: Test circuit for performance graphs
IEC MIN
10
100
1.5
1.25
1
0.75
0.5
0.25
0
-0.25
-0.5
-0.75
-1
-1.25
-1.5
0.1
POSITIVE ENERGY
NEGATIVE ENERGY
IEC MIN
1
100
GRAPH 2 - Linearity PF=+0.5,FREQ=50Hz,Vnom,TEMP=25°C
GRAPH 1 - Linearity PF=1,FREQ=50Hz,Vnom,TEMP=25°C
0.5
0.4
0.3
IEC MAX
0.2
%ERROR
%ERROR
10
I (Amp)
I (Amp)
1.5
1.25
1
0.75
0.5
0.25
0
-0.25
-0.5
-0.75
-1
-1.25
-1.5
0.1
IEC MAX
NEGATIVE ENERGY
POSITIVE ENERGY
0
-0.1
POSITIVE ENERGY +5.5V
POSITIVE ENERGY +4.5V
-0.2
IEC MIN
-0.3
-0.4
-0.5
1
10
0.1
100
I (Amp)
10
1
I (Amp)
GRAPH 3 - Linearity PF=-0.5,FREQ=50Hz,Vnom,TEMP=25°C
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POSITIVE ENERGY +5V
0.1
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GRAPH 4 - Linearity PF=1,Supply=+5.5V,+5V,+4.5V
100
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SA2102D
p(t)
FUNCTIONAL DESCRIPTION
The SA2102D is a CMOS integrated circuit, which performs
power/energy calculations across a dynamic range of 1000:1
to an accuracy that exceeds the IEC 61036 Class 1
specification.
where
The integrated circuit includes all the required functions for
single phase power and energy measurement. Two A/D
converters sample the voltage and current inputs. The
calculations required for power and energy are performed and
pulses on the LED, MON and MOP outputs represent the
results.
=
VM I M sin(wt + q ) sin(wt + y )
=
VM I M sin(wt + q ) sin(wt + q - j )
=
VRMS I RMS [cos j - cos(2(wt + q ) - j )]
v(t) is the instantaneous voltage
i(t) is the instantaneous current,
VM is the maximum amplitude of the voltage signal,
IM is the maximum amplitude of the current signal,
q is the voltage phase angle,
y is the current phase angle and
VI cos(2(wt + q ) - j ) = 100Hz noise component
on a 50Hz mains system.
This power information is then integrated over time to provide
the average power information.
Internal offsets are eliminated through the use of cancellation
techniques. The SA2102D generates pulses at a frequency
that is proportional to the power consumption. Complimentary
output pins MOP and MON are provided for driving a stepper
motor. A MOP pulse followed immediately by a MON pulse
represents an energy pulse. This minimizes the risk of (after
power up) losing the first energy pulse as a result of the stepper
motor residing in the wrong phase.
1
p (t )dt
T ò0
=V
RMS I RMS cos j
T
Average Power (P)
=
Where p(t) is the instantaneous power and
cos jis the power factor.
ANALOG INPUT CONFIGURATION
The LED output is normally proportional to the average power
consumption measured. When in FAST mode, the LED output
is proportional to the instantaneous active power consumption.
The FAST mode is intended for meter calibration purposes.
The input circuitry of the current and voltage sensor inputs is
illustrated in figure 5.
V DD
The two A/D converters convert the signals on the voltage and
current sense inputs to a digital format for further processing.
The current sense inputs (IIP and IIN) are identical and
balanced. A input signal with a range of 1:1000 is measured at
these inputs.
IIP
CURRENT
SENSOR
INPUTS
An integrated anti-creep function prevents any output pulses if
the measured power is less than 0.02% of the meters rated
current.
VSS
VDD
IVP
VOLTAGE
SENSOR
INPUT
= VM sin(wt + q ) ´ I M sin(wt +y )
j = q -y , VRMS =
AI
VDD
IIN
The two digital signals, accurately representing the current and
voltage inputs, are multiplied using digital multiplication. The
output of the multiplier is the instantaneous power.
For voltage and current in phase instantaneous power is
calculated by:
Instantaneous power p(t) = v(t ) ´ i (t )
let
VSS
V SS
AV
IM
VM
, I RMS =
2
2
GND
DR-01148
Figure 5: Analog input configuration
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sames
SA2102D
These inputs are protected against electrostatic discharge
through clamping diodes.
The values for resistors R1 and R2 can be calculated as
follows:
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.
R1 = R2 = (IL/16µA) x RSH/2
Where IL
=
Line current
RSH
=
Shunt resistor or termination
resistor if a CT is used as the current sensor.
The current and voltage sense inputs are both identical. Both
inputs are differential current driven up to ±25µA peak. One
input of the voltage sense amplifier is internally connected to
AGND. This is possible because the voltage sense input is
much less sensitive to externally induced parasitic signals
compared to the current sense inputs.
The value of RSH, if used as the CT's termination resistor,
should be less than the DC resistance of the CT's secondary
winding. The voltage drop across RSH should not be less
than 20mVRMS at IM XA
Voltage Sense Input (IVP)
The current into the A/D converter should be set at 14µARMS at
Nominal Mains Voltage (VNOM). This is to allow a variation of
±10% for the mains voltage without saturating the voltage
sense input. The voltage sense input saturates at an input
current of ±25µA peak. Referring to Figure 6 the typical
connections for the voltage sense input is illustrated.
Resistors R3, R4 and R5 set the current for the voltage sense
input. The Nominal Mains Voltage is divided down to 14VRMS.
The current into the A/D converter input is set at 14µARMS via
resistor R5 of value 1MW.
POWER CONSUMPTION
The power consumption of the SA2102D integrated circuit is
less than 25mW.
INPUT SIGNALS
Voltage Reference (VREF)
A bias resistor of 47kW sets optimum bias and reference
conditions on chip. Calibration of the SA2102D should be done
on the voltage input as described in the Typical Application
section and not on the Vref input.
Fast Mode Select (FAST)
The FAST pin is used to select between STANDARD and
FAST mode. Leaving this pin open or connecting to Vss
enables the STANDARD mode and connecting to Vdd
enables FAST mode.
Current sense input (IIP and IIN)
Figure 6 shows the typical connections for the current sensor
input. The resistor R1 and R2 define the current level into the
current sense inputs of the SA2102D. At Maximum Rated
Mains current (IMAX) the resistor values should be selected for
an input current of 16µARMS.
When STANDARD mode is enabled the LED output pulses at
a low frequency. This low frequency allows a longer
accumulation period and the output pulses are therefore
proportional to the average power consumption measured.
VDD
N
Supply
L
VDD
Supply
REVERSE
VDD
The Rated Select Condition pins (R0,R1 andR2) are used to
select different LED output frequencies which in turn selects
the applications meter constant. Refer to figure 8 for the LED
output timing diagram in STANDARD mode.
PULSES
DIRO DIRI
R1
IIN
Rsh
LED
IIP
R2
R3
When the FAST mode is enabled the LED output generates
pulses at a frequency of 1160Hz at IMAX and VNOM. In this
mode the pulse frequency is proportional to the
instantaneous power consumption measured. This mode is
used for meter calibration purposes and can also be used
when interfacing to a microcontroller. Refer to figure 9 for the
LED output timing diagram in FAST mode.
R5
IVP
SA2102D
8 8 8 8 8 8 8
AGND
R4
P1
MOP
MON
VREF VSS FAST SO R0 R1 R2
L
DR-01568
LOAD
N
Figure 6: Application circuit
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sames
SA2102D
Select Output (SO)
The SA2102D has unique internal circuitry that can be user
enabled to stabilize the LED output. When in FAST mode,
connecting the SO input pin to Vdd will enable the LED pulse
stability feature. Stabilizing the LED pulse output allows for
shorter meter calibration times. Leaving the SO pin open or
connecting to Vss will disable the LED pulse stability circuitry.
Figure 9 indicates the operation of pulse stability.
Table 3 shows some of the meter constants available for
several maximum currents (IMAX) and with a line voltage of
220V while in STANDARD mode.
Note that the values calculated using formulae 1 and 2 are
close approximations to the values listed in table 3. The
SA2102D has to be calibrated (using the voltage input) to give
the exact value listed.
Rated Condition Select (R0, R1, R2)
The Rated Condition Select pins R0, R1 and R2 are inputs pins
used to configure the SA2102D for different Maximum Rated
Mains Currents and Nominal Mains Voltages. This feature
allows for the use of different stepper motor gear ratios.
To calculate the LED output pulse rate (in STANDARD mode)
and motor drive pulse rate for any meter ratings (IMAX and VNOM)
the following formulae can be used:
LED pulses / kWh =
1160 x (1/DF_LED) x
3600
(VNOM x IMAX) / 1000
......... 1
Where:
IM XA = Maximum Rated Mains current
VNOM = Nominal Mains Voltage
DF_LED is the dividing factor and depends on R2, R1 and R0:
R2
R1
R0
DF_LED
0
0
0
322
0
0
1
322
0
1
0
322
0
1
1
322
1
0
0
536
1
0
1
214
1
1
0
214
Table 1: LED Output Constants
R0
DF_MO
0
64
0
1
32
1
0
16
1
1
8
0
0
220V/10A
6400
100
0
0
1
220V/20A
3200
100
0
1
0
220V/40A
1600
100
0
1
1
220V/80A
800
100
1
0
0
220V/6A
6400
100
1
0
1
220V/30A
3200
100
1
1
0
220V/60A
1600
100
Connecting DIRI to VDD will result in energy only being
measured in the positive direction. Energy flowing in the
negative direction will not be measured. Connecting DIRI to
VSS will result in energy only being measured in the negative
direction. Energy flowing in the positive direction will not be
measured. Connecting the DIRI pin to the DIRO output pin
enables the bi-direction mode where energy is measured
regardless of direction.
Table 2: MOTOR Output Constants
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0
Direction Select Input (DIRI)
Depending on the state of the DIRI pin the energy to be
measured can be in the positive direction only, or in the
negative direction only, or in both directions.
Where:
......... 2
LED pulses / kWh as calculated in formula 1
DF_MO is the dividing factor and depends on R1 and R0:
0
R1 R0 Vnom / Imax LED Output MOP and MON
(Pulses/
Outputs
kWh)
(Pulses/kWh)
Table 3: Some meter constants available for several maximum
currents (IMAX) and with a line voltage of 220V, while in
STANDARD mode.
Motor pulses / kWh = LED pulses/kWh / DF_MO
R1
R2
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SA2102D
OUTPUT SIGNALS
Motor pulse output (MOP, MON)
The MOP and MON pins are complimentary outputs with a
frequency proportional to the average power consumption
measured. These outputs can be used to either directly drive a
stepper motor counter or an electro mechanical impulse
counter. The Rated Conditions Select pins (R0, R1, R2) allows
the selection of different output frequencies corresponding to
different Meter Constants. Figure 7 indicates the timing of
these signals.
In FAST mode the LED pulse output is set at a high frequency
of 1160Hz at IMAX and VNOM. This mode is useful for fast
calibration and can be used to interface to a micro-controller.
Figure 9 indicates the LED output signal in FAST mode.
POWER
Instantaneous Power
t4
VDD
t1
0V
Time
Current
MOP
Voltage
VSS
Pulse stability
disabled
t2
VDD
MON
67 - 70 µS
VSS
t3
Pulse stability
enabled
t1 = t2 = t3 = 213ms
t4 is proportional to the average power and can be calculated
using Equation 2 and the Motor Output Constants in Table 2.
67 - 70 µS
Figure 7: Motor output MON and MOP
Figure 9: LED pulse output in fast mode
LED Output (LED)
The LED output pin provides a pulse output with a frequency
proportional to the average energy when in STANDARD mode
and the instantaneous energy when in FAST mode. This
output is primarily used for calibration purposes. The Rated
Conditions Select pins (R0, R1, R2) allow different frequencies
to be selected. The LED output is active low. Figure 8 shows
the LED waveform when in STANDARD mode.
t1
To convert pulses per kilowatt-hour to frequency (in Hz ) or vice
versa the following equations can be used:
Frequency (pulses per second) = P/kWh
P/kWh = frequency x
t2
3600
IxV
1000
(
3600
IxV
1000
(
)
)
Vdd
Vss
t1 = 90ms
t2 is proportional to the average power and can be calculated
using Equation 1 along with the appropriate LED Output
Constant in Table 1.
Figure 8: LED pulse output in STANDARD mode
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where:
P/kWh = LED or MON/MOP pulse constant
I = current in amperes
V = voltage (normally VNOM)
Direction Indicator Output (DIRO)
The direction energy flow may be ascertained by monitoring
the DIRO pin. A logic 0 on this pin indicates negative energy
flow. Positive energy flow, is indicated on pin DIRO as a logic 1.
The DIRO pin may be used to drive a LED.
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SA2102D
TYPICAL APPLICATION
VOLTAGE DIVIDER
In figure 10, the components required for a stand alone power
metering application, are shown. The application uses a shunt
resistor for the mains current sensing. The meter is designed
for 220V/40A operation.
The voltage divider is calculated for a voltage drop of 14V +
5%(14.7V). Equations for the voltage divider in figure 10 are:
R1 + R2 + R3 = RA and R12 || (R11+P1) = RB. Combining the
two equations gives:
The critical external components for the SA2102D integrated
circuit are the current sense resistors, the voltage sense
resistors as well as the bias setting resistor.
(RA + RB) / 220V = RB / 14.7V
BIAS RESISTOR
R13 defines all on-chip and reference currents. With
R13=47kW, optimum conditions are set. Device calibration is
done on the voltage input of the device.
SHUNT RESISTOR
The voltage drop across the shunt resistor at rated current
should be at least 20mV. If a shunt resistor of 625µW is chosen
and a voltage of 25mV across the shunt is required at IMAX
then the power dissipation in the current sensor is:
2
P=I R
=(40A)² x 625µW
= 1W.
CURRENT SENSE RESISTORS
The resistors R6 and R7 define the current level into the
current sense inputs of the device. The resistor values are
selected for an input current of 16µA on the current inputs of
the SA2102D at IMAX.
A 5k trimpot will be used in the voltage channel for meter
calibration. The center position on the pot is used in the
calculations. P1 = 2.5kW and values for resistors R11 = 22kW
and R12 =1MW are chosen.
Substituting the values will result in:
RB=23.91kW and RA=RB x (220V/14.7V - 1) resulting in
RA=333kW so the resistor values of R1, R2 and R3 are chosen
to be 110kW.
PROGRAMMING
The resistor values are calculated for a 40A rated meter. The
LED pulse rate must be set accordingly by programming pins
R0, R1 and R2. Using the Rated Conditions Select section,
pins R0 and R2 is set to VSS and R1 set to VDD. These
settings will configure the SA2102D for 220V/40A operation
with a LED pulse rate of 1600 pulses/kWh. The FAST pin is set
to VSS for STANDARD operation.
According to equation described in the Current Sense inputs
section:
R6 = R7 = (IL / 16µA) x RSH/2
= 40A / 16µA x 625µ/2
= 781.25W
A resistor with value of 820W is chosen, the 5% deviation from
the calculated value will be compensated for when calculating
resistor values for the voltage path.
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SA2102D
C5
R10
NEUTRAL
D1
+2V5
R4
+ C3
D3
+ C4
D4
C2
LIVE
P1
C1
D2
R5
R11
-2V5
R1
R2
R3
R12
R14
U1
R6
1
R7
2
3
+2V5
4
5
R13
C6
6
7
NEUTRAL
8
9
LIVE
DR-01569
-2V5
10
IIN
AGND
IIP
IVP
VREF
DIRI
R2
DIRO
R1
NC
R0
MON
FAST
VSS
VDD
LED
CNF
MOP
NC
SO
SA2102D
20
19
- 2V5
R9
18
Direction
17
16
5 4 3 2 1 .12
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ICNT1
15
14
13
+2V5
-2V5
R8
12
11
-2V5
220V/40A meter with 1600 pulses/kWh resolution
Figure 10: Application circuit
LED2
LED1
Calibration
sames
SA2102D
Parts List for Application Circuit: Figure 10
Symbol
Description
U1
D1
D2
D3
D4
R1
R2
R3
R4
R5
R6
R7
R8
R9
SA2102D
Diode, Silicon, 1N4002
Diode, Silicon, 1N4002
Diode, Zener, 2.4V
Diode, Zener, 2.4V
Resistor, 110k, 1/4W, 1%, metal
Resistor, 110k, 1/4W, 1%, metal
Resistor, 110k, 1/4W, 1%, metal
Resistor, 680, 1/4W, 1%, metal
Resistor, 680, 1/4W, 1%, metal
Resistor, 820, 1/4W, 1%, metal
Resistor, 820, 1/4W, 1%, metal
Resistor, 2K, 1/4W
Resistor, 2K, 1/4W
R10
R11
R12
R13
R14
Resistor, 47R, 2W, 5%, wire wound
Resistor, 22k 1/4W, 1%, metal
Resistor, 1M, 1/4W, 1%, metal
Resistor, 47k, 1/4W, 1%, metal
Shunt resistor 625µW
Trim pot, 5k, Multi turn
Capacitor, 220nF, Ceramic
Capacitor, 220nF, Ceramic
Capacitor, 100uF, 16V, electrolytic
P1
C1
C2
C3
C4
C5
Capacitor, 100uF, 16V, electrolytic
Capacitor, 330nF, 250VAC
C6
LED1
Capacitor, 820nF, Ceramic
3mm Light emitting diode
LED2
ICNT1
3mm Light emitting diode
Stepper Motor
Note 1: Resistor (R6 and R7) values are dependant on the selected shunt resistor (R14) value.
Note 2: Capacitor C6 to be positioned as close as possible to supply pins.
ORDERING INFORMATION
Part Number
Package
SA2102DPA
PDIP20
SA2102DSA
SOIC20
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Detail
PDIP20/SOIC20
Note 1
Note 1
Note 1
Note 2
sames
SA2102D
PDIP20 Outline Package
PACKAGE DIMENSIONS
Dimensions shown in inches.
SOIC20 Outline Package
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SA2102D
NOTES:
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PM9607AP
SA2102D
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.
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SYSTEMS (PTY) LTD
Tel: (012) 333-6021
Tel: Int +27 12 333-6021
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