Programmable Single Phase Kilowatt-hour
Energy IC for Mechanical Counter
Application
SA2002P
FEATURES
+
Provides a single chip solution for energy meters with a
+
+
+
+
+
+
mechanical display
No external crystal or resonator required
Precision on chip oscillator (<60ppm/°C drift)
Direct stepper motor/impulse counter drive
Calibration and setup stored on external EEPROM - no
trimpots required
Flexible programmable features
Unidirectional and bi-directional power and energy
measurement
sames
+
+
+
+
+
+
+
+
Can measure AC or DC energy.
Meets the IEC 61036 Specification for Class 1 AC Watt
hour meters
Less than 1% error over a dynamic range of 1:1000
Protected against ESD
Total power consumption rating below 30mW
Adaptable to different types of sensors
Operates over a wide temperature range
Precision voltage reference on-chip (<100ppm/°C drift)
DESCRIPTION
The SAMES SA2002P provides a single chip solution for
single phase mechanical counter based energy meters. A
precision oscillator, that replaces an external crystal is
integrated on chip.
The SA2002P does not require any external trim-pots. All
required calibration and configuration data is read from a small
external EEPROM. The data stored in the EEPROM consists
of direction mode (unidirectional or bidirectional), calibration
data, meter rated conditions, LED pulse rate, counter pulse
width, counter resolution and creep threshold. A
programmable high frequency pulse output is available on the
LED output for meter calibration purposes.
The SA2002P single phase kWh metering integrated circuit
generates a pulse rate with a frequency proportional to the
power consumption. The SA2002P performs active power
measurement and takes the power factor into account.
The SA2002P integrated circuit is available in 16 pin dual-in-
line plastic (PDIP16) and small outline (SOIC16) package
types.
V
DD
V
SS
IIP
DIRO
POWER
IIN
INTEGRATOR
ANALOG
SIGNAL
PROCESSING
VOLTAGE
REF.
IVP
IIC BUS
GND
OSC
TIMING
RLOAD
INTERFACE
FMO
TO
PULSE RATE
MOP
POWER
LED
MON
DR-01607
VREF
TEST
SCL
SDA
Figure 1: Block diagram
SPEC-0087 (REV. 5)
1/14
05-09-02
SA2002P
sames
#
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
Symbol
Min
-25
2.25
-2.75
Typ
Max
+85
2.75
-2.25
Unit
°C
V
V
mA
mA
Condition
T
O
V
DD
V
SS
I
DD
I
SS
5
5
6
6
I
I I
-25
+25
µA
Peak value
Voltage Sensor Input (Asymmetrical)
Input Current Range
Pin VREF
Ref. Current
Ref. Voltage
Digital I/O
Pins RLOAD, TEST, SDA
Input High Voltage
Input Low Voltage
Pins MOP, MON, LED, FMO,
SCL, DIRO
Output High Voltage
Output Low Voltage
Pin SDA
Pull up current
Pin RLOAD, TEST
Pull down current
V
I H
V
I L
V
OH
V
OL
V
DD
-1
V
SS
+1
V
DD
-1
V
SS
+1
V
V
V
V
I
OH
= -2mA
I
OL
= 5mA
I
I V
-I
R
V
R
-25
45
1.1
50
+25
55
1.3
µA
µA
V
Peak value
With R = 24k
W
connected to V
SS
Reference to V
SS
-I
I L
I
I H
24
48
54
110
µA
µA
V
I
= V
SS
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
Min
3.6V
-150
-40
-40
Max
6.0
+150
+125
+85
Unit
V
mA
°C
°C
V
DD
-V
SS
I
PI N
T
STG
T
O
*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
ATTENTION!
Electrostatic
sensitive devices.
Requires special
handling.
2/14
SA2002P
sames
Description
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.
Analog Input for Voltage. 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. 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 24k
W
resistor
connected to V
SS
set 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.
Test input. For normal operation this pin must be connected to V
SS.
Calibration LED output. Refer to section LED Output (LED) for the pulse rate output options.
PIN DESCRIPTION
Pin
16
5
9
15
Designation
GND
V
DD
V
SS
IVP
1, 2
IIN, IIP
3
12
11
7, 8
10
13
4
6
14
VREF
SCL
SDA
MON, MOP
TEST
LED
RLOAD
FMO
DIRO
Triggers the SA2002P to reload data from the external EEPROM.
Mains zero crossing output.
Direction output. This output indicates the energy flow direction.
ORDERING INFORMATION
IIN
IIP
VREF
RLOAD
V
DD
FMO
MON
MOP
1
2
3
4
5
6
7
8
dr-01606
16
15
14
13
12
11
10
9
Part Number
GND
IVP
DIRO
LED
SCL
SDA
TEST
V
SS
Package
PDIP16
SOIC16
SA2002PPA
SA2002PSA
Figure 2: Pin connections: Package: PDIP16, SOIC16
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SA2002P
sames
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 constants 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.
FUNCTIONAL DESCRIPTION
The SA2002P 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.
Various pulse outputs (MOP, MON and LED) are available.
The pulse rate on these pins follows the active power
consumption measured.
A 5V stepper motor may be driven directly from the SA2002P
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 SA2002P configures itself from an external low cost
EEPROM that contains all meter configuration and calibration
data. No external trimming is required. Calibration of the
device may be fully automated.
POWER CALCULATION
In Figure 9, the voltage drop across the shunt r
esistor should
be more than 16mV at rated load current. The voltage is
converted to current by means of resistors R
10
and R
11
. The
current sense input saturates at an input current of ±25µA
peak.
ELECTROSTATIC DISCHARGE (ESD)
PROTECTION
The SA2002P integrated circuit's input's/outputs are protected
against ESD.
POWER CONSUMPTION
The power consumption rating of the SA2002P integrated
circuit is less than 30mW.
V DD
IIP
CURRENT
SENSOR
INPUTS
VSS
VDD
A
I
IIN
VSS
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
(1M
W)
.
See Device Configuration for more details on the processing of
measured energy to frequency outputs.
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.
VDD
IVP
VOLTAGE
SENSOR
INPUT
V SS
A
V
GND
DR-01288
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.
Figure 3: Analog input internal configuration
http://www.sames.co.za
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SA2002P
INPUT SIGNALS
VREF
A bias resistor of 24k
W
set optimum bias conditions on chip.
Calibration of the SA2002P should be done as described in the
Device Configuration section.
sames
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 SA2002P. For
normal operation of the SA2002P the RLOAD pin may be left
floating.
Current sense input (IIP and IIN)
Figure 9 on page 11 shows the typical connections for the
current sensor input. The resistor R6 and R7 define the current
level into the current sense inputs of the SA2002P. At
maximum rated current the resistor values should be selected
for input currents of 16µA
RMS
.
The values for resistors R6 and R7 can be calculated as
follows:
R6 = R7 = (IL/16µA) x RSH/2
Where:
IL
=
Line current or line current/CT ratio
RSH
=
Shunt resistor or termination
Resistor if a CT is used as the current sensor.
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
16mV
RMS
at rated currents.
Test Input (TEST)
The TEST input is the manufacturers test pin and must be
connected to V
SS
for normal operation.
OUTPUT SIGNALS
Motor Output (MOP, MON)
The motor pulse width is programmable for 71ms, 142ms and
284ms. The MON pulse will follow the MOP pulse within the
selected pulse width time. This prevents the motor armature
being 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.
VDD
MOP
VSS
VDD
MON
VSS
DR-01559
Voltage Sense Input (IVP)
The current into the A/D converter should be set at 14µA
RMS
at
nominal mains voltage. 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 9 the typical connections for the
voltage sense input is illustrated. Resistors R1, R2 and R3 set
the current for the voltage sense input. The mains voltage is
divided down to 14V
RMS
. The current into the A/D converter
input is set at 14µA
RMS
via resistor R12.
t
m
t
m
t
m
Figure 4: Motor drive on MON and MOP pins
LED Output (LED)
The LED pin provides a pulse output and is intended for
calibration purposes. Depending on register Cled the pulse
rate can be either in slow mode or fast mode. When in slow
mode the pulse rate is a low frequency and is proportional to
the average power consumption. In fast mode the pulse rate is
a programmable high frequency output proportional to the
instantaneous power consumption. This mode is useful for fast
calibration times or can be used to interface to a micro-
controller. In slow mode the pulse width (tled) is 1ms and in fast
mode tled is 71µs. The LED output is active low as shown in
figure 5.
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 and the SA2002P. 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. The SCL output uses a soft driver and may be
overdriven by the calibration equipment.
VDD
LED
VSS
DR-01332
t
LED
Figure 5: LED pulse output
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