sames
PM9603AP
SA9603B APPLICATION NOTE
FEATURES
n
Performs both power and energy
measurement
n
Meets the accuracy requirements for
Class 1 AC Watt hour meters
n
Protected against ESD
n
Total power consumption rating below
500mW (excluding current sensing)
SINGLE PHASE POWER/ENERGY METERING MODULE
SPI INTERFACE
n
Uses a shunt resistor for current sensing
n
Operates over a wide temperature
range
n
Isolated SPI interface.
DESCRIPTION
The SAMES single phase power/energy metering module, the PM9603AP, provides
energy data via a isolated SPI 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 micro-controller.
The application utilises the SAMES SA9603B power metering integrated circuit 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.
7131
PDS038-SA9603B-001
REV.A
5-09-97
1/16
PM9603AP
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ABSOLUTE MAXIMUM RATINGS*
Parameter
Symbol
Min
Max
Unit
Supply Voltage (Note 1)
V
AC
300
V
Current Sense Input (Note 1)
V
IV
-2.5
+2.5
V
Storage Temperature
T
STG
-25
+125
C
Operating Temperature
T
O
-10
+70 (Note 2)
C
Max Current
I
MAX
800 (Note 3)
A
through Sensor
I
MAX
2000 (Note 4)
A
Note 1: Voltages are specified with reference to Live.
Note 2: The SA9603B integrated circuit is specified to operate over the temperature
range -10C to +70C. 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.
BLOCK DIAGRAM
D R -0 1 3 4 9
P O W E R
S U P P L Y
L IV E
V O L T A G E S E N S E
N E U T R A L
N E U T R A L
N E U T R A L
IN
O U T
IN
S H U N T
S A 9 6 0 3 B
P O W E R
M E T E R
W IT H
S P I B U S
D-
s
u
b
CO
NNE
CT
O
R
O P T O -
C O U P L E R
O P T O -
C O U P L E R
PM9603AP
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ELECTRICAL CHARACTERISTICS
(Over the temperature range -10C to +70C, unless otherwise specified. Power
consumption figures are applicable to the PM9603APE only.)
Parameter
Symbol
Min
Typ
Max
Unit
Condition
Supply Voltage
V
AC
180
230
265
V
PM9603APE
(Continuous)
90
115
135
V
PM9603APA
Power Measurement
P
RNG
-18400
18400
W
Specified
range
accuracy
Power Consumption
1
800
m W
V
AC
= 230V
Supply direct
from mains
Isolation Voltage
2
V
IS
2500
V
Continuous
Opto-coupler Output
Current
I
O
10
mA
V
OL
= 1V
Opto-coupler Input
Current
I
I
10
mA
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
MAINS
Voltage supply connection to Neutral line
Voltage supply connection to Live line
NEUTRAL IN
Connection to positive side of current sensor
NEUTRAL OUT
Connection to negative side of current sensor
SK1
P1 Supply (+ve) to opto-couplers
25-Way female
P2 Input SA9603B - SCK
(D-type)
P8 Input SA9603B - DI
P9 Input SA9603B - CS
P12 Output SA9603B - DO
P18, 20-25 Common emitters and cathodes opto-couplers
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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 16A
RMS
(0 to 80A through a shunt resistor of 625
). The
current input stage of the module, saturates at input currents greater than 18A
RMS
.
The mains voltage (Voltage + 15% - 20%) is used to supply the circuitry with power.
A SA9603B utilize current information from the current sensor (shunt resistor),
together with the mains voltage to perform the power calculation.
The SA9603B 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 on chip registers are accessed via the isolated SPI bus.
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 reference of the module is connected to neutral.
5. Isolated Input/Output Interface
The isolated interface is provided to allow the user to access the registers of the
SA9603B.
A 25-Way D type connector (female) is provided on the PM9603AP module. The
connector SK1 connects via a one to one connected cable to a Personal Computer
parallel port.
6. Circuit Description
In the Application Circuits, (Figures 1), 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.
PM9603AP
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The current sense input requires a differential approach to cater for precision across
the dynamic range. It is therefore important that the PC board layout of the branches
to the sensing element, are as symmetrical as possible and the loop area is kept to
a minimum.
The most important external components for the SA9603B integrated circuit are:
R
2
, R
1
and RSH are the resistors defining the current level into the current sense input.
The values should be selected for an input current of 16A
RMS
into the SA9603B at
rated line current.
Values for RSH of less than 200
should be avoided.
R
1
= R
2
= (I
L
/16A
RMS
) * RSH/2
Where
I
L
=
Line current
RSH =
Shunt resistor/termination resistor
R
3
, R
6
and R
4
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 14A
RMS
.
R
7
defines all on-chip bias and reference currents. With R
7
= 24k
, 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 and supplies the A/D converters
and the digital circuitry.
7. Demonstration Software
Software which runs under Windows 3.1 and Windows 95 is provided with each
evaluation module. See README.TXT on the diskette supplied for the installation
instructions.
8. Sample C source code
The following software demonstrates how to synchronize the reading of the registers
to the SA9603B's internal offset cancellation scheme. The software is also available
on the SAMES Internet web pages.
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