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SA9103 / SA9603C APPLICATION NOTE
PM9103AP
SINGLE PHASE POWER/ENERGY METERING MODULE
SERIAL INTERFACE
FEATURES
n
Performs both power and energy
measurement
n
Uses a shunt resistor for current
sensing
n
Meets the accuracy requirements for
Class 1 AC Watt hour meters
n
Operates over a wide temperature
range
n
Protected against ESD
n
n
Total power consumption rating below
500mW (excluding current sensing)
Serial interface having a RS232
Protocol
DESCRIPTION
The SAMES single phase power/energy metering module, the PM9103AP, provides
energy data via a RS232 compatible serial interface.
Energy consumption is determined by the power measurement being integrated over
time.
The method of calculation takes the power factor into account.
The output of this innovative universal power/energy meter is ideally suited for energy
calculations in applications using a µ-controller.
The application utilises the SAMES SA9103CP, SA9103EP or SA9603CP power
metering integrated circuits for power measurement.
As a safety measure, this application shows the current sensor connected to the neutral
line. In practice, the live line may be used for current sensing, provided that the supply
connections (MAINS) are reversed on the module.
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PM9103AP
BLOCK DIAGRAM
NEUTRAL
IN
SHUNT
OUT
NEUTRAL
POWER
SUPPLY
LIVE
SA9103
SA9603
OPTO
COUPLER
POWER
METER
OPTO
COUPLER
VOLTAGE SENSE
D-sub CONNECTOR
NEUTRAL
DR-01448
ABSOLUTE MAXIMUM RATINGS*
Parameter
Symbol
Supply Voltage (Note 1)
VAC
Current Sense Input (Note 1)
VIV
Storage Temperature
TSTG
Operating Temperature
TO
Max Current
IMAX
through Sensor
IMAX
Min
-2.5
-25
-10
Max
540
+2.5
+125
+70 (Note 2)
800 (Note 3)
2000 (Note 4)
Unit
V
V
°C
°C
A
A
Note 1: Voltages are specified with reference to Live.
Note 2: The SA9103 and SA9603C integrated circuits are specified to operate over the
temperature range -10°C to +70°C. The module functionality will however
depend upon the external components used.
Note 3: t = 500ms
Note 4: t = 1ms
*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 conditions 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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ELECTRICAL CHARACTERISTICS
(Over the temperature range -10°C to +70°C, unless otherwise specified. Power
consumption figures are applicable to the PM9103APE only.)
Parameter
Symbol
Supply Voltage
(Continuous)
Power Measurement
range
VAC
Opto-coupler Output
Current
Opto-coupler Input
Current
Typ
Unit
Condition
V
V
W
PM9103APE
PM9103APA
Specified
accuracy
800
mW
VAC = 230V
Supply direct
from mains
VIS
2500
V
IO
10
mA
II
10
mA
P RNG
180
230
90
115
-18400
Max
265
135
18400
Power Consumption1
Isolation Voltage2
Min
Continuous
VOL = 1V
Note 1: Power consumption specifications exclude power consumed by the current
sensor.
Note 2: Isolation voltage may be specified, depending on customer requirements.
CONNECTION DESCRIPTION
Designation
Description
Voltage supply connection to Neutral line
MAINS
Voltage supply connection to Live line
NEUTRAL IN
Connection to positive side of current sensor
NEUTRAL OUT
SK1
D-sub connector
9-Pin
Connection to negative side of current sensor
Serial Input
Serial Output
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FUNCTIONAL DESCRIPTION
1. Power Calculation
In the Application Circuit (see Figure 2), the output current from the current sensor
will be between 0 and 16µA (0 to 80A through a shunt resistor of 625µΩ). The current
input stage of the module, saturates at input currents greater than 18µARMS. T h e
mains voltage (Voltage + 15% - 20%) is used to supply the circuitry with power and
to perform the power calculation, together with the current information from the
current sensor (shunt resistor).
The SA9103CP, SA9103EP and SA9603C integrated circuits may be adjusted to
accommodate any voltage or current values. The method for calculating external
component values is described in paragraph 6 (Circuit Description).
SAMES offers two evaluation module options, namely 230V/80A and 115V/80A.
The calculated power is integrated into a 22 bit integrator, which is accessable via
a serial interface having a RS232 protocol. The power calculation takes the power
factor into account.
2. Electrostatic Discharge (ESD) Protection
The device's inputs/outputs are protected against ESD according to the Mil-Std
883C, method 3015. The modules resistance to transients will be dependant upon
the protection components used.
3. Power Consumption
The overall power consumption rating for this power metering application (Figure 2),
is under 500mW, excluding the current sensor, when the supply is taken directly from
the mains.
4. Isolation
The serial interface is isolated from the module which is at mains potential, via two
opto-couplers. (In the event of the use of a current transformer for current sensing,
the opto-couplers would not be required.)
5. Serial Interface
Reading and resetting of the on-chip integrators may be performed using a Personel
Computer (PC). A standard serial cable should be used to connect SK1 to the PC.
The computers port settings are as follows:
19 200 Baud
1 Start bit
1 Stop bit
No parity bits
The Serial Interface allows for the following operations:
Read Integrator: The device transmits the current integrator status to the controller,
after the current measurement cycle has been completed (8 mains periods maximum).
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PM9103AP
Reset Integrator:
status.
The integrator is reset without transmitting the integrator
Read/Reset Integrator: The device 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 on-chip
integrator using the "Read" command.
If after a "Read" command, the integrator value is sufficiently high, a "Read/Reset"
command from the controller causes the integrated circuit to complete the existing
measurement cycle, transmit the 16 most significant bits of the 22 bit integrator
via the Serial Output, to the controller and restart the integrator.
The most significant bit of the 16 bits, indicates the direction of energy consumption
measured (0 = Positive, 1 = Negative).
Refer to the SA9103C, SA9103E or SA9603C datasheets for the serial interface
command protocols.
6.
Circuit Description
The Application Circuit (figure 2) shows the components required for the serial
interface power metering module, using a shunt resistor for current sensing.
In this application the device requires +2.5V, 0V, -2.5V DC supply.
The most important external components are:
C1 and C2 are the outer loop capacitors of the two integrated oversampling A/D
converters. The value of these capacitors is 560pF. The actual values determine
signal to noise and stability performance. The tolerance 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.
R2, R1 and RSH are the resistors defining the current level into the current sense
input. The values should be selected for an input current of 16µARMS into the SA9103
/ SA9603C at maximum line current.
Values for RSH of less than 200µΩ should be avoided.
R1 = R2 = IL/16µARMS * RSH/2.
Where
IL
= Line current
RSH
= Shunt resistor/terminating 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 14µARMS.
R7 defines all on-chip bias and reference currents. With R7 = 24kΩ, optimum
conditions are set.
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XTAL is a colour burst TV crystal (f = 3.5795MHz) for the oscillator. The oscillator
frequency is divided down to 1.7897MHz on-chip and supplies the A/D converters
and the digital circuitry.
7.
Demonstration Software
Software which runs under Windows 3.1 is provided with each evaluation module.
See README.TXT on the diskette supplied for the installation instructions.
Figure 1: Connection Diagram
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APPLICATION CIRCUIT
Figure 2: Application using a Shunt Resistor for Current Sensing, having a PC
(Personal Computer) Interface.
Note:
The Serial Interface having a RS232 protocol, has been designed to operate
directly with a PC (Personal Computer).
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Parts List For Application Circuit: Figure 2
Item
Symbol
Description
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
IC-1
IC-2
IC-3
D1
D2
D3
ZD1
ZD2
XTAL
R1
R2
R3A
R3B
R4
R5
R6
R7
R8
R9
R10
R12
R13
R14
R15
C1
C2
C3
C4
C9
C10
C11
C12
C13
C14
C15
RSH
SA9103CP/SA9103EP/SA9603C
Opto Coupler 4N35
Opto Coupler 4N35
Diode, Silicon, 1N4148
Diode, Silicon, 1N4148
Diode, Silicon, 1N4148
Diode, Zener, 2.4V, 200mW
Diode, Zener, 2.4V, 200mW
Crystal, 3.5795MHz
Resistor, 1.6kΩ, 1%, metal
Resistor, 1.6kΩ, 1%, metal
Resistor, 1%, metal
Resistor, 1%, metal
Resistor, 1M, ¼W
Resistor, 470Ω, 2W, 5%, carbon
Resistor, 24k, ¼W, metal
Resistor, 24k, ¼W, metal
Resistor, 680Ω, ¼W, 5%
Resistor, 680Ω, ¼W, 5%
Resistor, 680Ω, ¼W, 5%
Resistor, 120Ω, ¼W, 5%
Resistor, 120k, ¼W, 5%
Resistor, 3.9k, ¼W, 5%
Resistor, 120Ω, ¼W, 5%
Capacitor, 560pF
Capacitor, 560pF
Capacitor, 3.3nF
Capacitor, 3.3nF
Capacitor, 100nF
Capacitor, 100nF
Capacitor, polyester
Capacitor, 100nF
Capacitor, 100µF, 16V
Capacitor, 100µF, 16V
Capacitor, 820nF, 16V
Shunt Resistor, 80A, 50mV (625µΩ)
Detail
DIP-20
DIP-6
DIP-6
Colour burst TV
Note 1
Note 1
Note 2
Note 2
Note 2
Note 1
Note 1: Resistor (R1 and R2) values are dependant upon the selected value of RSH. See
paragraph 6 (Circuit Description) when selecting the value for RSH.
Note 2: See the table below, detailing the component values for the selected voltage standard.
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Item
Symbol
12
13
31
R3A
R3B
C11
Description
PM9103APA
PM9103APE
115V
230V
120kΩ
200kΩ
82kΩ
180kΩ
1µF
0.47µF
Detail
ORDERING INFORMATION
Part Number
PM9103APA
PM9103APE
Description
115V, 80A Module
230V, 80A Module
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Disclaimer:
The information contained in this document is confidential and proprietary to South African MicroElectronic 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 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:
Fax:
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012 333-6021
012 333-8071
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Tel:
Fax:
Int +27 12 333-6021
Int +27 12 333-8071