Single Phase Power / Energy IC
with SPI Interface
SA9903B
+
FEATURES
+
Bi-directional active
+
+
+
and reactive power/energy
sames
+
+
+
+
+
+
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
measurement
RMS Voltage and frequency measurement
SPI communication bus
Meets the IEC 521/1036 Specification requirements for
Class 1 AC Watt hour meters
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.
TEST
VDD
VSS
ACTIVE
IIP
IIN
CURRENT
ADC
REACTIVE
SPI
IVP
RMS
VOLTAGE
VOLTAGE
ADC
MAINS.
FREQ.
FMO
GND
VOLTAGE
REF.
OSC
DI
DO
SCK
CS
Dr-01583
VREF
OSC1
OSC2
Figure 1: Block diagram
SPEC-0051 (REV. 2)
1/12
26-02-01
SA9903B
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
Oscillator
Pin VREF
Ref. Current
Ref. Voltage
Digital I/O
Pins SCK
High Voltage
Low Voltage
V
IH
V
IL
f
SCK
t
LO
t
HI
Pins CS, DI
High Voltage
Low Voltage
Pins FMO, DO
Low Voltage
High Voltage
V
IH
V
IL
V
OL
V
OH
V
DD
-1
V
SS
+1
800
0.6
0.6
V
DD
-1
V
SS
+1
V
SS
+1
V
DD
-1
V
V
kHz
µs
µs
V
V
V
V
I
IV
-25
+25
µA
I
II
-25
+25
µA
Symbol
T
O
V
DD
V
SS
I
DD
I
SS
Min
-25
2.25
-2.75
3.56
3.56
Typ
Max
+85
2.75
-2.25
5.1
5.1
Unit
°C
V
V
mA
mA
sames
Condition
Peak value
Peak value
Recommended crystal: TV colour burst crystal f = 3.5795 MHz
-I
R
V
R
45
1.1
50
55
1.3
µA
V
With R = 24kW
connected to V
SS
Reference to V
SS
I
OL
= 5mA
I
OH
= -2mA
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
-40
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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3
SA9903B
PIN DESCRIPTION
PIN
20
8
Designation
GND
V
DD
Description
sames
Analog Ground. The supply 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 24kW resistor connected to V
SS
sets the optimum operating condition.
Manufacturers test pin, connect to V
SS
for normal operation.
Connections for a crystal or ceramic resonator. (OSC1 = input; OSC2 = Output)
Serial clock in. This pin is used to stobe data in and out of the SA9903B
Serial data out. Data from the SA9903B is strobed out on this pin. DO is
only driven when CS is active.
Voltage zero crossover. The FMO output generates a pulse (50% duty cycle)
on every rising edge of the mains voltage.
Serial data in. Data is only accepted during an active chip select (CS).
Chip select. The CS pin is active high.
Manufacturers Test Pins. (Leave unconnected)
14
V
SS
19
IVP
1, 2
IIN, IIP
3
7
10, 11
12
13
15
17
18
4, 5, 6, 9, 16
VREF
TEST
OSC1, OSC2
SCK
DO
FMO
DI
CS
TP4, TP5, TP6,
TP9, TP16
IIN
IIP
VREF
TP4
TP5
TP6
TEST
VDD
TP9
OSC2
1
2
3
4
5
6
7
8
9
10
DR-01225
20
19
GND
IVP
ORDERING INFORMATION
Part Number
SA9903BPA
SA9903BSA
Package
DIP-20
SOIC-20
18 CS
17 DI
16 TP16
15 FMO
14 VSS
13 DO
12
SCK
11 OSC1
Figure 2: Pin connections: Package: DIP-20, SOIC-20
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SA9903B
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.
sames
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
16µA
RMS
. Values for resistors R6 and R7 may be calculated as
follows:
R6 = R7 = (I
L
/ 16µA ) x RSH / 2
Where I
L
= Max line current
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
RMS
.at nominal mains
voltage by means of resistors R1, R2, R3 and R4. The current
into the voltage sense input is set at 14µA
RMS
with resistor R5
from the voltage divider. The voltage sense input of the AD
converter saturates at an input current of ±25µA 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).
A
I
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
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. The current and voltage sense inputs are
identical. Both inputs are differential current driven up to ±25µA
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.
V DD
IIP
CURRENT
SENSOR
INPUTS
VSS
VDD
IIN
VSS
VDD
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.
IVP
VOLTAGE
SENSOR
INPUT
V SS
A
V
GND
DR-01288
Figure 3: Analog input internal configuration
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SA9903B
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.
sames
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.
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.
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:
ID
1
2
3
4
Register
Active
Reactive
Voltage
Frequency
Header
A5 A4 A3 A2 A1 A0
bits
1
1
1
1
1
1
1
1
0
0
0
0
X
X
X
X
X
X
X
X
0
0
0
0
0
0
0
0
0
0
1
1
0
1
0
1
POWER CONSUMPTION
The power consumption rating of the SA9903B integrated
circuit is less than 25mW.
Voltage
FM0
+5V (V
DD
)
0V (V
SS
)
Dr-01498
Figure 4: Mains voltage zero corssover pin FMO
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