+ FEATURES
+
Bi-directional active and reactive power/energy
measurement
+
RMS Voltage and frequency measurement
+
SPI communication bus
+
Meets the IEC 521/1036 Specification requirements for
Class 1 AC Watt hour meters
sames
sames
Single Phase Power / Energy IC
with SPI Interface
SA9903B
1/12
SPEC-0051 (REV. 2)
26-02-01
+
Meets the IEC 1268 Specification requirements for VAR
hour meters
+
Protected against ESD
+
Total power consumption rating below 25mW
+
Adaptable to different current sensor technologies
+
Operates over a wide temperature range
+
Precision voltage reference on-chip
DESCRIPTION
The SAMES SA9903B is a single phase bi-directional
energy/power metering integrated circuit that performs
measurement of active and reactive power, mains voltage and
mains frequency.
The SA9903B is pin compatible to the SA9603B. New features
include, RMS mains voltage and accurate reactive power
measurements.
Measured values for active and reactive energy, the mains
voltage and frequency are accessible through a SPI bus from
24 bit registers.
This innovative universal single phase power/energy metering
integrated circuit is ideally suited for energy calculations in
applications such as electricity dispensing systems (ED's),
residential municipal metering and factory energy metering
and control.
TheSA9903B integrated circuit is available in both 20 pin dual-
in-line plastic (DIP-20), as well as 20 pin small outline (SOIC-
20) package types.
Figure 1: Block diagram
IVP
SPI
VOLTAGE
REF.
DI
VSS
VDD
DO
FMO
VREF
Dr-01583
OSC2
OSC1
GND
ACTIVE
REACTIVE
RMS
VOLTAGE
MAINS.
FREQ.
CURRENT
ADC
VOLTAGE
ADC
SCK
CS
OSC
IIP
IIN
TEST
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sames
SA9903B
2/12
3
http://www.sames.co.za
ELECTRICAL CHARACTERISTICS
#
(V = 2.5V, V = -2.5V, over the temperature range -10C to +70C , unless otherwise specified.)
DD
SS
Operating temp. Range
C
V
A
A
T
O
V
DD
I
II
I
IV
-25
-25
-25
2.25
+25
+25
+85
2.75
Peak value
Peak value
I = 5mA
OL
I = -2mA
OH
Condition
Unit
Max
Typ
Min
Symbol
Parameter
V
V
SS
-2.75
-2.25
I
DD
5.1
3.56
mA
I
SS
5.1
3.56
mA
V
V
V
IH
V
IL
f
SCK
t
LO
t
HI
V -1
DD
V +1
SS
kHz
s
s
0.6
0.6
800
V
V
V
IH
V
IL
V -1
DD
V +1
SS
V
V
V -1
DD
V +1
SS
V
OL
V
OH
Recommended crystal: TV colour burst crystal f = 3.5795 MHz
With R = 24kW
connected to V
SS
Reference to V
SS
A
V
45
1.1
55
1.3
-I
R
V
R
50
ABSOLUTE MAXIMUM RATINGS*
Supply Voltage
V -V
-0.3
6.0
V
DD
SS
Current on any pin
I
-150
+150
mA
PIN
Storage Temperature
T
-40
+125
C
STG
Operating Temperature
T
-40
+85
C
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.
Parameter
Symbol
Min
Max
Unit
Current Sensor Inputs (Differential)
Voltage Sensor Input (Asymmetrical)
Input Current Range
Supply Voltage: Positive
Supply Voltage: Negative
Supply Current: Negative
Supply Current: Positive
Input Current Range
Pin VREF
Ref. Current
Ref. Voltage
Oscillator
Pins SCK
High Voltage
Low Voltage
Pins CS, DI
High Voltage
Low Voltage
Pins FMO, DO
Low Voltage
High Voltage
Digital I/O
3/12
sames
sames
SA9903B
http://www.sames.co.za
Figure 2: Pin connections: Package: DIP-20, SOIC-20
Part Number
SA9903BPA
SA9903BSA
Package
DIP-20
SOIC-20
ORDERING INFORMATION
PIN DESCRIPTION
Analog Ground. The supply voltage to this pin should be mid-way between
V and V .
DD
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.
GND
V
DD
Designation
Description
PIN
20
8
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.
V
SS
14
Analog Input for Voltage. The current into the A/D converter should be set at
14A
at nominal mains voltage. The voltage sense input saturates at an
RMS
input current of 25A peak.
19
IVP
Inputs for current sensor. The shunt resistor voltage from each channel is
converted to a current of 16A
at rated conditions. The current sense input
RMS
saturates at an input current of 25A peak.
1, 2
IIN, IIP
This pin provides the connection for the reference current setting resistor.
A 24kW resistor connected to V
sets the optimum operating condition.
SS
3
VREF
Manufacturers test pin, connect to V
for normal operation.
SS
7
TEST
Connections for a crystal or ceramic resonator. (OSC1 = input; OSC2 = Output)
10, 11
OSC1, OSC2
Serial clock in. This pin is used to stobe data in and out of the SA9903B
12
SCK
Serial data out. Data from the SA9903B is strobed out on this pin. DO is
only driven when CS is active.
13
DO
Voltage zero crossover. The FMO output generates a pulse (50% duty cycle)
on every rising edge of the mains voltage.
15
FMO
Serial data in. Data is only accepted during an active chip select (CS).
17
DI
Chip select. The CS pin is active high.
18
CS
Manufacturers Test Pins. (Leave unconnected)
4, 5, 6, 9, 16
TP4, TP5, TP6,
TP9, TP16
1
IIN
GND
IIP
IVP
FMO
CS
VSS
VREF
TP4
TP5
TP6
TEST
VDD
DI
TP16
DO
SCK
TP9
OSC2
OSC1
2
3
4
5
6
15
14
13
12
11
10
9
8
7
16
17
18
19
20
DR-01225
4/12
sames
sames
SA9903B
Figure 3: Analog input internal configuration
http://www.sames.co.za
FUNCTIONAL DESCRIPTION
The SA9903B is a CMOS mixed signal Analog/Digital
integrated circuit, which performs the measurement of active
power, reactive power, RMS voltage and mains frequency. The
integrated circuit includes all the required functions for single-
phase power and energy measurement such as two
oversampling A/D converters for the voltage and current sense
inputs, power calculation and energy integration.
The SA9903B integrates instantaneous active and reactive
power in 24 bit integrators. RMS voltage and frequency is
continuously measured and stored in respective registers. The
mains voltage zero crossover is available on the FMO output.
The SPI interface of the SA9903B has a tri-state output that
allows connection of more than one metering device on a
single SPI bus.
INPUT SIGNALS
Analog Input Configuration
The input circuitry of the current and voltage sensor inputs is
illustrated in figure 3. These inputs are protected against
electrostatic discharge through clamping diodes. The
feedback loops from the outputs of the amplifiers A and A
I
V
generate virtual shorts on the signal inputs. Exact duplications
of the input currents are generated for the analog signal
processing circuitry. The current and voltage sense inputs are
identical. Both inputs are differential current driven up to 25A
peak. One of the voltage sense amplifier input terminals is
internally connected to GND. This is possible because the
voltage sense input is much less sensitive to externally
induced parasitic signals compared to the current sense
inputs.
Current Sense Input (IIP and IIN)
Figure 8 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 SA9903B. At rated current the
resistor values should be selected for input currents of
16A
. Values for resistors R6 and R7 may be calculated as
RMS
follows:
R6 = R7 = (I / 16A ) x RSH / 2
L
Where I = Max line current
L
RSH = Shunt resistor or termination resistor.
The voltage drop across RSH should not be less than 16mV at
rated currents. In case a current transformer is used for current
sensing the value of RSH should be less than the resistance of
the CT's secondary winding.
Voltage Sense Input (IVP)
The mains voltage is divided to 14V
.at nominal mains
RMS
voltage by means of resistors R1, R2, R3 and R4. The current
into the voltage sense input is set at 14A
with resistor R5
RMS
from the voltage divider. The voltage sense input of the AD
converter saturates at an input current of 25A peak.
Reference Voltage (VREF)
The VREF pin is the reference for the bias resistor. With a bias
resistor of 24kW optimum conditions are set. It may be varied
within 10% for calibration purposes.
Serial Clock (SCK)
The SCK pin is used to synchronize data interchange between
the micro controller and the SA9903B. The clock signal on this
pin is generated by the micro controller and determines the
data transfer rate of the DO and DI pins.
Serial Data In (DI)
The DI pin is the serial data input pin for the SA9903B. Data will
be input at a rate determined by the Serial Clock (SCK). Data
will be accepted only during an active chip select (CS).
Chip Select (CS)
The CS input is used to address the SA9603B. An active high
on this pin enables the SA9903B to initiate data exchange.
VOLTAGE
SENSOR
INPUT
IVP
DR-01288
SS
V
CURRENT
SENSOR
INPUTS
IIP
IIN
SS
V
VDD
SS
V
VDD
DD
V
GND
A
V
A
I
5/12
sames
sames
SA9903B
http://www.sames.co.za
OUTPUT SIGNALS
SERIAL DATA OUT (DO)
The DO pin is the serial data output pin for the SA9903B. The
Serial Clock (SCK) determines the data output rate. Data is
only transferred during on active chip select (CS). This output
is tri-state when CS is low.
MAINS VOLTAGE SENSE ZERO CROSSOVER
(FMO)
The FMO output generates a signal, which follows the mains
voltage zero crossings, see figure 4. The micro controller may
use the FMO to extract mains timing.
ELECTROSTATIC DISCHARGE (ESD) PROTECTION
The SA9903B Integrated Circuit's inputs/outputs are protected
against ESD.
POWER CONSUMPTION
The power consumption rating of the SA9903B integrated
circuit is less than 25mW.
Figure 4: Mains voltage zero corssover pin FMO
ID
1
2
3
4
Register
Active
Reactive
Voltage
Frequency
1
1
1
1
1
1
1
1
0
0
0
0
A5
X
X
X
X
A4
X
X
X
X
A3
0
0
0
0
A2
0
0
0
0
A1
0
0
1
1
A0
0
1
0
1
Header
bits
SPI - INTERFACE
DESCRIPTION
A serial peripheral interface bus (SPI) is a synchronous bus
used for data transfers between a micro controller and the
SA9903B. The pins DO (Serial Data Out), DI (Serial Data In),
CS (Chip Select), and SCK (Serial Clock) are used in the bus
implementation. The SA9903B is the slave device with the
micro controller the bus master. The CS input initiates and
terminates data transfers. A SCK signal (generated by the
micro controller) strobes data between the micro-controller
and the SCK pin of the SA9903B device. The DI and DO pins
are the serial data input and output pins for the SA9903B,
respectively.
REGISTER ACCESS
The SA9903B contains four 24 bit registers. The content
represents active energy, reactive energy, mains voltage and
mains frequency. The register addresses are shown in the
following table:
Dr-01498
Voltage
+5V (V )
DD
0V (V )
SS
FM0
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