sames

FEATURES

Performs power measurement and di-
rectly drives a 5 digit (7 segment) LED
display

Accuracy better than 1% (± 1 count)

Protected against ESD

Total power consumption rating below
800mW

1/10

Uses a shunt resistor or for current
sensing

Operates over a wide temperature
range

Precision voltage reference on-chip

SINGLE PHASE WATT MEASUREMENT MODULE

WITH A 5 DIGIT LED DISPLAY

4358

PDS038-SA9106-001

REV. A

06-09-1995

SA9106 APPLICATION NOTE

PM9106AP

DESCRIPTION
The SAMES single phase Watt measurement module, the PM9106AP includes an on-
board 5 digit (7 segment) Light Emitting Diode (LED) display. Active power is directly
displayed in watts, with a full scale of 20 000 watts.

The measured power is updated approximately every 2 seconds, giving an average
power reading for this period.

This method of calculation takes the power factor into account.

This innovative universal Watt measurement module is ideally suited for the display of
the measured power in single phase, industrial and domestic power measurement
applications.

The application utlises the SAMES SA9106AP single phase Watt measurement
integrated circuit for power measurement and display.

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.

PM9106AP

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BLOCK DIAGRAM

ABSOLUTE MAXIMUM RATINGS*

Parameter

Symbol

Min

Max

Unit

Supply Voltage (Note 1)

540

Current Sense Input (Note 1)

-2.5

+2.5

Storage Temperature

STG

-25

+125

°C

Operating Temperature (Note2)

-10

+70

°C

Note 1:

Voltages are specified with reference to Live.

Note 2:

The SA9106AP integrated circuit is specified to operate over the temperature
range -10°C to +70°C. The module functionality will however depend upon
the external components used.

*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.

NEUTRAL
(Mains)

NEUTRAL IN

NEUTRAL OUT

LIVE

POWER

SUPPLY

SHUNT

SA9106A

WATT

METER

DR-00913

5-DIGIT

LED

DISPLAY

PM9106AP

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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 625

). The current

input stage saturates at input currents greater than18µA

RMS

. The mains voltage

(230V + 15% -20%) is used to supply the circuitry with power and for the power
calculation, together with the current information from the current sensor (shunt
resistor).

The SA9106AP integrated circuit may be adjusted to accomodate any voltage or
current values. The method of calculating external component values is described
in paragraph 5 (Circuit Description).

SAMES offers two evaluation module options, namely 230V/80A and 115/80A.

ELECTRICAL CHARACTERISTICS
(Over the temperature range -10°C to +70°C, unless otherwise specified.)

Parameter

Symbol

Min

Typ

Max

Unit

Condition

Supply Voltage

180

230

265

Continuous
operation

Power Consumption

800

= 230V

Note 1: Power consumption specifications exclude power consumed by the current

sensor.

Note 2: Isolation voltage may be specified, depending on customer requirements.

PIN 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

The calculated power is directly displayed on a 5 digit (7 segment) LED display. The
update interval is approximately every 2 seconds.

PM9106AP

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LED Display
The PM9106AP has an on-board LED display comprising 5 (7 segment) common
cathode digits, as well as a sign LED.

The sign LED is addressed by DIG [5], the most significant digit by DIG [4] and the
least significant digit by DIG [0].

The position of the segments a, b, c, d, e, f and g are given in the diagram below:

The full scale power displayed is 20 000 watts. An overflow is indicated by a flashing
display.

Electrostatic Discharge (ESD) Protection
The device's inputs/outputs are protected against ESD according to Mil-Std 883C,
method 3015. The modules resistance to transients will be dependant upon the
protection components used.

Power Consumption
The overall power consumption rating for this power metering application (Figure 2),
is under 800mW, excluding the current sensor.

Circuit Description
The Application Circuit (Figure 2) shows the components required for the Watt
measurement module, using a shunt resistor for current sensing.

DR-00914

a
a

PM9106AP

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5/10

The most important external components for the SA9106AP device are:

and C

are the outer loop capacitors for 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 optimum
tolerances should be within ± 10%.

and C

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.

, R

and R

are the resistors defining the current level into the current sense input.

The values should be selected for an input current of 16µA

RMS

into the SA9106AP

at rated line current.

Values for RSH of less than 200µ

should be avoided.

= R

= (I

/16µA

RMS

) * R

Where

Line current

Shunt resistor/termination resistor

, R

and R

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.

defines all on-chip bias and reference currents. With R

= 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.

PM9106AP

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Parts List for Application circuit: Figure 2

Item Symbol Description

Detail

IC-1

SA9106A

DIP-40

IC-2

5V 100mA Voltage Regulator

IC-3