Datasheet SA9122EFA, SA9122EPA Datasheet (SAMES)

sames

SA9122E

SINGLE PHASE UNIDIRECTIONAL POWER/ENERGY

METERING IC WITH SEPERA TE 64 SEGMENT LCD DRIVER

FEATURES

n Performs unidirectional power and

energy measurement

n On-chip 64 segment LCD driver
n Meets the IEC 521/1036 Specification

requirements for Class 1 AC Watt hour
meters

n Total power consumption rating below

n Adaptable to different types of current

sensors

n Operates over a wide temperature

range

n Different pulse rate options available

for power information

n LCD data input via a serial interface

25 mW

DESCRIPTION

PIN CONNECTIONS

The SAMES SA9122E Single Phase
unidirectional active Power/Energy metering
integrated circuit includes a seperate on­chip 64 segment Liquid Crystal Display driver.
The power/energy metering circuit generates
a pulse rate output, proportional to the power
consumption, while the LCD driver is
programmable via a serial interface.

The method of power calculation takes the
power factor into account. Energy consump­tion is determined by the power measurement
being integrated over time.

The LCD driver is capable of driving 8 decimal
digits (7 segment) and 8 announciators on a
4 track multiplexed backplane display.

This innovative combination energy metering/
LCD display driver integrated circuit has
been designed to provide meter designers
with flexibility in the choice of the µ-controller
employed, and is ideally suited for applica­tions such as residential municipal metering
and factory energy metering and control.

The SA9122E integrated circuit is available
in both 40 pin dual-in-line plastic (DIP-40), as
well as 44 pin plastic leaded chip carrier

RX
V

CIP
CIN

COP
CON
IVN
IIP
IIN
GND
VREF
CPON
CPOP
CPIN
CPIP

V
R[0]

R[1]
R[2]
R[3]

1
2

SS

3
4
5
6
7
8

9
10
11
12
13
14
15
16

DD

17
18
19
20

DR-00932

Package: DIP-40

(PLCC-44) package types.

4362 PDS039-SA9122E-001 REV. A 19-09-1995

FOUT2

40
39

FOUT1

38

OSC1
OSC2

37

S[15]

36
35

S[14]
S[13]

34
33

S[12]

32

S[11]

31

S[10]

30

S[9]

29

S[8]
S[7]

28
27

S[6]

26

S[5]

25

S[4]

24

S[3]

23

S[2]

22

S[1]

21

S[0]

1/12

SA9122E

]

]

]

]

S[14]S[11

S[12

S[13

38

39 37 36 35

N.C.

S[10

34

S[9]

S[8]

33 32 31

S[7]

30

S[6]

29

S[5]

BLOCK DIAGRAM

IIP

IIN

IVP

GND

ANALOG

SIGNAL

PROCE-

S[15]
OSC2
OSC1
FOUT1
FOUT2
N.C.
RX

V

SS
CIP
CIN
COP

DR-00934

SSING

40
41
42
43
44
1
2
3
4
5
6

7

CON

IVN

12

981011

IIP

IIN

N.C.

GND

13 14 15

Package: PLCC-44

POWER

INTEG­RATOR

VOLTAGE

REF.

OSC

16

17

CPON

CPIN

VREF

CPOP

FREQUENCY

SRAM

SERIAL

INTERFACE

28

S[4]

27

S[3]

26

S[2]

25

S[1]

24

S[0]

23

N.C.

22

R[3]

21

R[2]

20

R[1]

19

R[0]

18

V

CPIP

V

V

DD

SS

POWER

TO

SEGMENT

DRIVERS

BACKPLANE

DRIVERS

DD

FOUT1
FOUT2

S[15]

S[0]

R[3]

R[0]

2/12

DR-00933

VREF OSC1

sames

OSC2 RX

SA9122E

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

-40 +85 °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.

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

DD

SS

DD

SS

Current Sensor Inputs (Differential)
Input Current Range I

II

Voltage Sensor Input (Asymmetrical)
Input Current Range I

IV

Pins FOUT1, FOUT2

Output Low Voltage V
Output High Voltage V

Pulse Rate FOUT1 f

FOUT2

1

OL

OH

P

f

P2

sames

2.25 2.75 V

-2.75 -2.25 V
57mA
57mA

-25 +25 µA Peak value

-25 +25 µA Peak value

VSS+1 V IOL = 5mA

VDD-1 V IOH = -2mA

10 1160 Hz Specified linearity

0.5 3000 Hz Min and max limits
fP/290

3/12

SA9122E

ELECTRICAL CHARACTERISTICS (Continued)

Parameter Symbol Min Typ Max Unit Condition

Oscillator Recommended crystal:

TV colour burst crystal f = 3.5795 MHz

Pin VREF With R = 24kΩ

Ref. Current -I
Ref. Voltage V

R
R

45 50 55 µA connected to V

1.1 1.3 V Referred to V

SS

SS

LCD backplane Voltage V

LCD segment Voltage V

B

s

VDD &

V

SS

1/3 V
2/3 V

DD
DD

R[0] ... R[3]

V
V

S[0] ... S[15]

Note1: Two additional bondout options at FOUT2 are available on request: fp/4 and

fp/16.

#

Extended Operating Temperature Range available on request.

PIN DESCRIPTION

PLCC-44 DIP-40 Designation Description

11 10 GND Ground
18 16 V

3 2 V

DD
SS

Positive Supply Voltage
Negative Supply Voltage

8 7 IVN Analog input for Voltage
10 9 IIN Inputs for current sensor
9 8 IIP
42 38 OSC1 Connections for crystal or ceramic resonator
41 37 OSC2 (OSC1 = Input ; OSC2 = Output)
14 12 CPON Connections for outer loop capacitor of
15 13 CPOP A/D converter (Voltage)
16 14 CPIN Connections for inner loop capacitor of
17 15 CPIP A/D converter (Voltage)

4 3 CIP Connections for inner loop capacitor of
5 4 CIN A/D converter (Current)
6 5 COP Connections for outer loop capacitor of
7 6 CON A/D converter (Current)

13 11 VREF Connection for current setting resistor

2 1 RX Serial data input
44 40 FOUT2 Pulse rate outputs
43 39 FOUT1

4/12

sames

PIN DESCRIPTION (Continued)

PLCC-44 DIP-40 Designation Description

19 17 R[0] Output drivers for LCD back planes
20 18 R[1]
21 19 R[2]
22 20 R[3]
24 21 S[0] Output drivers for LCD segments
25 22 S[1]
26 23 S[2]
27 24 S[3]
28 25 S[4]
29 26 S[5]
30 27 S[6]
31 28 S[7]
32 29 S[8]
33 30 S[9]
35 31 S[10]
36 32 S[11]
37 33 S[12]
38 34 S[13]
39 35 S[14]
40 36 S[15]
1 NC Not connected
12 NC
23 NC
34 NC

SA9122E

FUNCTIONAL DESCRIPTION

The SA9122E 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, and includes a seperate 64 segment LCD display driver function.

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 SA9122E generates pulses, the
frequency of which is proportional to the power consumption. Two frequency outputs
(FOUT1 and FOUT2) are available, with additional frequency options available on
request. The pulse rate follows the instantaneous power measured.

The separate Liquid Crystal Display driver function included on-chip, drives up to 64
segments on a 4 track muliplexed backplane display, programmable via a serial interface
having a RS232 protocol.

sames

5/12

SA9122E

1. Power calculation

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 (230VAC) is divided down through

a divider to 14V. The current into the A/D converter input is set at 14µA

RMS

mains voltage, via resistor R4 (1MΩ).
In this configuration, with a mains voltage of 230V and a current of 80A, the output

frequency of the SA9122E power meter chip at FOUT1 is 1.16kHz. In this case, 1
pulse will correspond to an energy consumption of 18.4kW/1160Hz = 15.9Ws.

The output frequency at FOUT2 is FOUT1 /290 (i.e. The frequency ouput at FOUT1
divided by 290).

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.

at nominal

6/12

sames

IIN

CURRENT
SENSOR
INPUTS

IIP

IVN

VOLTAGE
SENSOR
INPUT

DR-00935

V

DD

V

SS

V

DD

V

SS

V

DD

V

SS

GND

A

I

A

V

3. LCD Programming Protocol

Programming of the SA9122E's on-chip Liquid Crystal Display memory is performed
via a serial interface having a RS232 data format. The data for display is transferred
on RX at 19 200 baud.

The format of the data as well as the data memory map, is given below:

Data format on RX

SA9122E

START

DR-00937

A1A0

A3A2 D2D0 D1 STOPD3

LCD memory map

Inserting a '1' into a memory location turns the segment on and a '0' turns the
segment off.

A3 A2 A1 A0 D3 D2 D1 D0 Pin

0000 S[0]
0001 S[1]
0010 S[2]
0011 S[3]
0100 S[4]
0101 S[5]
0110 S[6]
0111 S[7]
1000 S[8]
1001 S[9]
1010 S[10]
1011 S[11]
1100 S[12]
1101 S[13]
1110 S[14]
1111 S[15]

R[3] R[2] R[1] R[0]

sames

7/12

SA9122E

4. Electrostatic Discharge (ESD) Protection

The SA9122E integrated circuit's inputs/outputs are protected against ESD according
to Mil-Std 883C, method 3015.

5. Power Consumption

The power consumption rating of the SA9122E integrated circuit is less than 25mW.

TYPICAL APPLICATIONS

In the Application Circuit (Figure 1), the components required for this power metering
application, 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.

The most important external components for the SA9122E 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.

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 16µA

into the SA9122E at

RMS

maximum line current.
Values for RSH of less than 200µΩ should be avoided.
R1 = R2 = (IL/16µA
Where I

L

) * RSH/2

RMS

= Line current

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

RMS

R7 defines the reference current (IR). With R7 = 24kΩ, optimum conditions are set. R
may be varied within ±10% for calibration purposes. Any change to R7 will affect the
output quadratically (i.e.: R7 = +5%, fP = +10%).

.

7

8/12

sames

The formula for calculating the output frequency is given below:
f = 11.16

3.58MHz I

FOUTX

*

FOSC * II .I

*

V

2

R

Where FOUTX = Normal rated frequency (4Hz or 1160Hz)

FOSC = Oscillator frequency (2MHz ...... 4MHz)

SA9122E

I

I

I

V

I

R

= Input current for current sensor input (16µA at rated line current)
= Input current for voltage sensor input (14µA at rated line voltage)
= Reference current (typically 50µA)

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

sames

9/12

SA9122E

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

R0R1R2

R3

LCD

. .. . . . . . . . . . . .

FROM MICRO-

CONTROLLER

TO MICRO-

CONTROLLER

RX

FOUT2

FOUT1

403839

1C43

2

SS

V

XTAL

37

4

C2

353436

675

R4R1R2

32

33

31

SA9122E

8

9

10

R6

30

292827

IC-1

11

121314

C1

. .

26

252324

1617181920

15

DD

V

C3

22

21

DR-00936

R7

C7

R8

C6

R9

R3

C5

10/12

LOAD

sames

RSH

+2.5

-2.5V

SUPPLY

Parts List for Application Circuit: Figure 1

Item Symbol Description Detail

1 IC-1 SA9122E DIP-40/PLCC-44
2 XTAL Crystal, 3.5795MHz Colour burst TV
3 R1 Resistor, 1% metal Note 1
4 R2 Resistor, 1% metal Note 1
5 R3 Resistor, 390k, (230VAC) 1%, metal
6 R4 Resistor, 1M, 1/4W, 1%, metal
7 R6 Resistor, 24k, 1/4W, 1%, metal
8 R7 Resistor, 24k, 1/4W, 1%, metal

9 R8 Resistor, 820Ω, 1/4W, 1%
10 R9 Resistor, 820Ω, 1/4W, 1%
11 C1 Capacitor, 560pF
12 C2 Capacitor, 560pF
13 C3 Capacitor, 3.3nF
14 C4 Capacitor, 3.3nF
15 C5 Capacitor, 100nF
16 C6 Capacitor, 100nF
17 C7 Capacitor, 820nF Note 2
18 LCD LCD 64 Segment, 4 back plane
19 RSH Shunt Resistor Note 3

SA9122E

Note 1: Resistor (R1 and R2) values are dependant upon the selected value of RSH.
Note 2: Capacitor (C7) to be positioned as close to Supply Pins (VDD & VSS) of IC-1 as

possible.

Note 3: See TYPICAL APPLICATIONS when selecting the value of RSH.

ORDERING INFORMATION

Part Number Package

SA9122EPA DIP-40
SA9122EFA PLCC-44

sames

11/12

SA9122E

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, 0039 Koedoespoort Industrial Area,
Republic of South Africa, Pretoria,

Republic of South Africa

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

12/12

sames