Datasheet SA9103CPA, SA9103CSA Datasheet (SAMES)

sames

TP9VOSC2

DD

CPON

CPOP

IIN

CPIN

CPIP

VREF

IIP

OSC1

SOUT

SIN

111213

CIP

CIN

COP

CON

GND

19141516171820

IVPVSS

FEATURES

SA9103C

SINGLE PHASE BIDIRECTIONAL POWER/ENERGY

METERING IC WITH SERIAL INTERF ACE

n Performs bidirectional active and

reactive power/energy, frequency and
voltage measurement

n Meets the IEC 521/1036 Specification

requirements for Class 1 AC Watt hour
meters

n Protected against ESD
n Total power consumption rating below

25mW

DESCRIPTION

The SAMES SA9103C bidirectional Single
Phase Power/Energy metering integrated
circuit has a serial interface with a RS232
protocol, ideal for use with a µ-Controller.
The SA9103C performs the calculation for
active and reactive power.

The integrated values for active and
reactive energy as well as the mains
frequency and voltage information are
accessable through the RS232-Interface
as 16 bit values.

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.

The SA9103C 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.

n Adaptable to different current sensor

technologies

n Operates over a wide temperature

range

n Serial interface having a RS232 protocol
n Precision voltage reference on-chip

n Tri-state output to allow parallel

connection of devices

PIN CONNECTIONS

1
2
3
4
5
6
7
8
9

10

DR-00829

Package: DIP-20

SOIC-20

4259

PDS039-SA9103C-001 REV. D 23-08-1996

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SA9103C

INTERFACE

SS

BLOCK DIAGRAM

V

DD

V

IIP

IIN

ANALOG

SIGNAL

ACTIVE

ENERGY

REACTIVE

ENERGY

FREQUENCY

VOLTAGE

SIN
SOUT

SERIAL

PROCE-

VOLTAGE

REF.

OSC

TIMING

OSC2

IVP

GND

DR-00830

SSING

VREF OSC1

ABSOLUTE MAXIMUM RATINGS*

Parameter Symbol Min Max Unit

Supply Voltage VDD -V
Current on any pin I

Storage Temperature T
Operating Temperature T

PIN

STG

O

SS

-0.3 6.0 V

-150 +150 mA

-40 +125 °C

-10 +70 °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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SA9103C

ELECTRICAL CHARACTERISTICS

(VDD = 2.5V, VSS = -2.5V, over the temperature range -10°C to +70°C#, unless otherwise
specified.)

Parameter Symbol Min Typ Max Unit Condition

Supply Voltage: Positive V
Supply Voltage: Negative V
Supply Current: Positive I
Supply Current: Negative I

2.25 2.75 V

DD

-2.75 -2.25 V

SS

DD

SS

56mA

56mA
Current Sensor Inputs (Differential)
Input Current Range I

-25 +25 µA Peak value

II

Voltage Sensor Input (Asymetrical)
Input Current Range I

IV

-25 +25 µA Peak value

Pin SOUT

Output Low Voltage V
Output High Voltage V

OL

VDD-1 V IOH = -2mA

OH

Pin SIN

Input High Voltage V
Input Low Voltage V
Pull-up Current -I

VDD-1 V

IH

IL

50 150 µA VIN = V

I

Oscillator Recommended crystal:

TV colour burst crystal f = 3.5795 MHz

VSS+1 V IOL = 5mA

VSS+1 V

SS

Pin VREF With R = 24kΩ

Ref. Current -I
Ref. Voltage V

#

Extended Operating Temperature Range available on request.

R
R

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45 50 55 µA connected to V

1.1 1.3 V Referred to V

SS

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SS

SA9103C

PIN DESCRIPTION

Pin Designation Description

20 GND Ground
8 V

14 V

DD

SS

Positive Supply Voltage

Negative Supply Voltage
19 IVP Analog input for Voltage
1 IIN Inputs for current sensor
2 IIP
11 OSC1 Connections for crystal or ceramic resonator
10 OSC2 (OSC1 = Input ; OSC2 = Output)
12 SOUT Serial Interface Out
13 SIN Serial Interface In
4 CPON Connections for outer loop capacitors of
5 CPOP A/D converter (Voltage)
6 CPIN Connections for inner loop capacitors of
7 CPIP A/D converter (Voltage)
15 CIP Connections for inner loop capacitors of
16 CIN A/D converter (Current)
17 COP Connections for outer loop capacitors of
18 CON A/D converter (Current)
3 VREF Connection for current setting resistor
9 TP9 Test Pin. Must be connected to V

SS

FUNCTIONAL DESCRIPTION

The SA9103C is a CMOS mixed signal Analog/Digital integrated circuit, which performs
power/energy calculations across a power range of 1000:1, to an overall accurancy of
better than Class 1.

The integrated circuit includes all the required functions for 1-phase power and energy
measurement, such as two 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 SA9103C integrates the measured
active and reactive power consumption into 22 bit integrators, which are accessable via
a serial port having a RS232 protocol. Two additional on-chip registers exist: one register
contains the mains frequency information; and the other the voltage information.

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1. Power calculation

AVA

In the Application Circuit (Figure 1), the voltage drop across the shunt will be
between 0 and 16mV (0 to 80A through a shunt resistor of 200µΩ). This voltage is
converted to a current of between 0 and 16µA, by means of resistors R1 and R2.

The current sense input saturates at an input current of ±25µA peak.
For the voltage sensor input, the mains voltage (230V AC) is divided down through

a divider to 14V. The resulting current into the A/D converter input is 14µA at
nominal voltage, via resistor R4 (1MΩ).

In this configuration, with a mains voltage of 230V and a current of 80A, the
SA9103C functions at its optimum conditions, having a margin of 3dB for overload
available.

2. Analog Input Configuration

The input circuitry of the current and voltage sensor inputs are illustrated below.
These inputs are protected against electrostatic discharge through clamping
diodes.

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.

V

DD

SA9103C

sames

IIP

CURRENT
SENSOR
INPUTS

IIN

IVP

VOLTAGE
SENSOR
INPUT

DR-00831

V

SS

V

DD

V

SS

V

DD

V

SS

GND

I

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SA9103C

3. Electrostatic Discharge (ESD) Protection

The SA9103C integrated circuit's inputs/outputs are protected against ESD .

4. Power Consumption

The power consumption rating of the SA9103C integrated circuit is less than 25mW.

5. Serial Interface

Reading and resetting of the SA9103C's on-chip integrators, is performed via the
serial interface.

The settings are: 19 200 Baud

1 Start bit (S)
1 Stop bit (E)

No parity bits

The serial interface, with RS232 protocol, has been designed to operate directly with
a PC (Personal Computer).

The serial interface allows for the following operations:
Read Integrator (RD): The SA9103C integrated circuit transmits the integrator

status to the controller, after the current measurement cycle has been completed
(8 mains periods maximum).

The register containing the mains frequency information is read only.
Reset Integrator (RES): The SA9103C integrator is reset, without transmitting the

integrator status.
Read/Reset Integrator (RD/RES): The SA9103C transmits the integrator status

and resets the integrator after the current measurement cycle has been completed.
In a typical application, the system controller monitors the status of the SA9103C's

integrator using the "Read" command. At rated load conditions, the capacity of the
22 bit integrator allows for an integration time of 2 seconds prior to integrator
overflow.

If after a "Read" command, the integrator value is sufficently high, a "Read/Reset"
command from the controller causes the SA9103C integrated circuit to complete the
existing measurement cycle, transmit the 16 most significant bits of the 22 bit
integrator via the Serial Output (SOUT) to the controller and restart the integrator.

In order to ensure correct measurements, the integrator commands ("Read" and
"Read/Reset") are only executed after completion of the internal offset calibration
cycle. The cycle length is 8 mains periods.

Thus, for power calculations, the time value should be taken from the difference in
time from the previously received energy value to the currently received value.

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SA9103C

BIT

RD

By adapting the "Read/Reset" rate to the line current the accuracy of the measurement
can be achieved down to lowest signal levels.

Read, Reset and Read/Reset of integrator for active energy

START

RD

RD

RES

RES

STOP

BIT

RD

RES

RD/
RES

DR-00832

Read, Reset and Read/Reset of integrator for reactive energy

START

BIT

RD

RD

RES

RES

STOP

BIT

RD

RES

RD/
RES

DR-00833

Read frequency register

RD

DR-00834

START

BIT

STOP

BIT

Read, Reset and Read/Reset of integrator for voltage

START

BIT

RD

RD

RES

RES

RD

RES

RD/
RES

DR-01152

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STOP

BIT

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SA9103C

5

The register access codes which can be written to the SA9103C via the serial
communications port are shown in the table below.

REGISTER READ RESET READ-RESET

ACTIVE $01 $02 $03
RE-ACTIVE $81 $82 $83
VOLTAGE $C1 $C2 $C3
FREQUENCY $41 - -

Data on SOUT

8 9 10 11 12 13 14 15

FIRST BYTE

DR-00835

01234

SECOND BYTE

From the two bytes of data output by the device, the value for the register can
be derived as shown:

Register value = (First Byte * 256) + Second Byte

The most significant bit of the 16 bit energy register (active or reactive) is an
indication of the direction of the energy flow (0 = positive, 1 = negative).

6. Register Values

a. The active and reactive energy measured per count, may be calculated by

applying the following formula:
Energy per Count =

V * I

K

Watt seconds

Where V = Rated Voltage

I = Rated Current
K = 9281 for Active Energy

9281 * 2

for Reactive Energy

π

b. The mains frequency may be calculated as follows:

Frequency =

Crystal frequency
Register Value * 8

67

c. To calculate the measured voltage, the following formula may be used:

Vmeasured =

V * n

14000 * t

Where V = rated voltage

t = time difference between successive reads
n = difference in register values between

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successive reads

7. Software flow

In an application in which all the registers must be accessed, the software loop
illustrated below can be implemented.

READ FREQUENCY COMMAND

DELAY OF 8 MAINS PERIODS

RECEIVE FREQUENCY
READ ACTIVE COMMAND

LOOP DELAY OF 8 MAINS PERIODS

SA9103C

∧∧

∧

∧∧

RECEIVE ACTIVE
READ REACTIVE COMMAND

DELAY OF 8 MAINS PERIODS

RECEIVE REACTIVE
READ VOLTAGE COMMAND

DELAY OF 8 MAINS PERIODS

RECEIVE VOLTAGE

The SA9103C integrated circuit transmits the register values only after completion
of the current measurement cycle (8 mains periods maximum).

The delay of 8 mains periods can be calculated from the period value of the
frequency returned by the initial read, and updated with each subsequent reading
of frequency.

Each successive read of the registers takes place regularly at intervals of 4 blocks
of 8 mains cycles. This time and the difference between successive energy register
values can be used to calculate power.

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SA9103C

8. Calibration

For the calibration of the SA9103C, the following procedure is recommended:

a. Establish calibration factor for active energy (Ka) at pf close to 1.

Active (Measured) = register_value (Active) * Ka. 1

b. The factor for reactive (Kr) is typically Ka * PI/2.

For higher accuracy of Kr, establish Kr at pf close to 0.

Reactive (Measured) = register_value (Reactive) * Kr 2

c. At pf close to 1, establish error for reactive (Er)

Er = (Reactive (Measured) - Reactive (True)) / Active (Measured) 3

Reactive (Corrected) = Reactive (Measured) - Er * Active (Measured) 3b

Measurement

Having determined the scaling factors (Ka & Kr) and error correction constant (Er)
the measurement cycle consists of the following steps:

step 1 Read active register

∨∨

∨

∨∨

step 2 Calculate Active (Measured) as per 1 Active energy

∨∨

∨

∨∨

⇒⇒

⇒

⇒⇒

step 3 Read reactive register

∨∨

∨

∨∨

step 4 Calculate Reactive (Measured) as per 2

∨∨

∨

∨∨

step 5 Perform error correction

Calculate Reactive (Corrected) as per 3b Reactive energy

⇒⇒

⇒

⇒⇒

The above five steps must be performed for each measurement cycle.

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SA9103C

TYPICAL APPLICATIONS

In the Application Circuits (Figures 1 and 2), the components required for power metering
applications, are shown.

In Figure 1 a shunt resistor is used for current sensing. In this application, the circuitry
requires a +2.5V, 0V, -2.5V DC supply.

In the case of Figure 2, when using a current transformer for current sensing, a +5V, 0V
DC supply is sufficient for the circuit.

The most important external components for the SA9103C integrated circuit are:
C1 and C2 are the outer loop capacitors for the two integrated oversampling A/D

converters. The value of these capacitors is 560pF. The actual values determine the
signal to noise and stability performance. The tolerances should be within ±10%.

C3 and C4 are the inner loop capacitors of the A/D converters. The optimum value is 3.3nF.
The actual values are uncritical. Values smaller than 0.5nF and larger than 5nF should
be avoided.

R1, R2 and RSH are the resistors defining the current level into the current sense input.
The values should be selected for an input current of 16µA into the SA9103C at rated line
current.

Values for RSH of less than 200µΩ should be avoided.
R1 = R2 = (IL/16µA) * RSH/2
Where I

= Line current

L

RSH = Shunt resistor/termination resistor

R3, R6 and R4 set the current for the voltage sense input. The values should be selected
so that the input current into the voltage sense input (virtual ground) is set to 14µA.

R7 defines all on-chip bias and reference currents. With R7 = 24kΩ, optimum conditions
are set.

XTAL is a colour burst TV crystal (f = 3.5795MHz) for the oscillator. The oscillator
frequency is divided down to 1.7897MHz on-chip to supply the A/D converters and digital
circuitry.

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SA9103C

Figure 1: Application Circuit using a Shunt Resistor for Current Sensing, having

a PC (Personal Computer) Interface.

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SA9103C

Part List for Application Circuit: Figure 1

Item Symbol Description Detail

1 IC-1 SA9103C DIP-20/SOIC-20
2 IC-2 Opto Coupler 4N35 DIP-6
3 IC-3 Opto Coupler 4N35 DIP-6
4 D1 Diode, Silicon, 1N4148
5 D2 Diode, Silicon, 1N4148
6 D3 Diode, Silicon, 1N4148
7 ZD1 Diode, Zener, 2.4V, 200mW
8 ZD2 Diode, Zener, 2.4V, 200mW

9 XTAL Crystal, 3.5795MHz Colour burst TV
10 R1 Resistor, 1% metal Note 1
11 R2 Resistor, 1% metal Note 1
12 R3 Resistor, 390k, (230VAC), 1% metal
13 R4 Resistor, 1M, 1/4W, 1% metal
14 R5 Resitor, 470Ω, 2W, 5%, carbon
15 R6 Resistor, 24k, 1/4W, 1%, metal
16 R7 Resistor, 24k, 1/4W, 1%, metal
17 R8 Resistor, 680Ω, 1/4W, 5%
18 R9 Resistor, 680Ω, 1/4W, 5%
19 R10 Resistor, 680Ω, 1/4W, 5%
20 R11 Resistor, 100k, 1/4W, 5%
21 R12 Resistor, 120Ω, 1/4W, 5%
22 R13 Resistor, 120k, 1/4W, 5%
23 R14 Resistor, 3.9k, 1/4W, 5%
24 R15 Resistor, 120Ω, 1/4W, 5%
25 C1 Capacitor, 560pF
26 C2 Capacitor, 560pF
27 C3 Capacitor, 3.3nF
28 C4 Capacitor, 3.3nF
29 C9 Capacitor, 100nF
30 C10 Capacitor, 100nF
31 C11 Capacitor, 0.47µF, 250VAC, polyester
32 C12 Capacitor, 100nF
33 C13 Capacitor, 100µF
34 C14 Capacitor, 100µF
35 C15 Capacitor, 820nF
36 RSH Shunt Resistor Note 2

Note 1: Resistor (R1 and R2) values are dependant upon the selected value of RSH.
Note 2: See TYPICAL APPLICATIONS when selecting the value for RSH.

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SA9103C

Figure 2: Application Circuit using a Current Transformer for Current Sensing.

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Parts List for Application Circuit: Figure 2

Item Symbol Description Detail

1 IC-1 SA9103C DIP-20/SOIC-20
2 XTAL Crystal, 3.5795MHz Colour burst TV
3 RSH Resistor Note 1
4 R1 Resistor, 1%, metal Note 2
5 R2 Resistor, 1%, metal Note 2
6 R3 Resistor, 390k, (230VAC) 1%, metal
7 R4 Resistor, 1M, 1/4W, metal
8 R6 Resistor, 24k, 1/4W, metal

9 R7 Resistor, 24k, 1/4W, metal
10 R8 Resistor, 2.2k, 1/4W, 5%
11 R9 Resistor, 2.2k, 1/4W, 5%
12 C1 Capacitor, 560pF
13 C2 Capacitor, 560pF
14 C3 Capacitor, 3.3nF
15 C4 Capacitor, 3.3nF,
16 C9 Capacitor, 820nF Note 3
17 C10 Capacitor, 100nF
18 C11 Capacitor Note 4
19 CT Current Transformer

SA9103C

Note 1: See TYPICAL APPLICATIONS when selecting the value of RSH.
Note 2: Resistor (R1and R2) values are dependant upon the selected value of

RSH.
Note 3: Capacitor (C9) to be positioned as close to IC-1, as possible.
Note 4: Capacitor (C11) selected for DC blocking and to minimize phase error

introduced by the current transformer.

Part Number Package

SA9103CPA DIP-20
SA9103CSA SOIC-20

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SA9103C

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:
[e-mail]

For the latest updates on datasheets, please visit out web site:
http://www.sames.co.za

South African Micro-Electronic Systems (Pty) Ltd

P O Box 15888, 33 Eland Street,
Lynn East, Koedoespoort Industrial Area,
0039 Pretoria,
Republic of South Africa, Republic of South Africa

Tel: [phone] Tel: Int [phone]
Fax: [phone] Fax: Int [phone]

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