Datasheet AS2591 Datasheet (Austria Mikro Systeme International)

Preliminary AS2591

SEGMENT

MULTIPLEXER

Austria Mikro Systeme International AG

16-Digit LCD Driver

CMOS Integrated Circuit

Key Features

q q 16-digit LCD driver on a 44 pin CMOS chip
q q Operating voltage range: 3.2 to 4.8V
q q Low power consumption: max. 150 µA
q q Driving 7-segment displays with up to 16 digits and

12 symbols

q q Option for 12 digits
q q Buffer for 32 digits
q q 4 backplanes
q q 2-wire interface
q q On chip timer for showing elapsed time
q q Contrast adjustable
q q On chip oscillator using 32.768 kHz crystal
q q Compatible with AS2525

Block Diagramme

V

DD

POR

BACKPLANE

COUNTER

General Description

The AS2591 is a CMOS integrated circuit for driving a
liquid crystal display intended for use in telephones.
The driver can be used with 12- or 16-digit LCDs.

The 2-wire serial interface is compatible with the
AS2525, single-chip handsfree telephone circuit.

The device is designed for LCDs with 4 backplanes
and 24 or 31 segments providing 12 or 16 7-segment
digits and 12 symbols.

The AS2591 also includes a timer for showing
elapsed time in minutes and seconds.

The contrast can be adjusted through the serial
interface.

Package

Available in 44 pin TQFP.

4

COM1-4

DI

SCLK

CS

32.768 kHz

V

LCD

SERIAL

I/F

COMMAND

DECODER

OSC

CONTRAST

VOLTAGE
CONTROL

7­SEGMENT
DECODER

DATA
ADDRESS
CONTROL

DIGIT

MEMORY

32 DIGITS

ELAPSE

TIME

COUNTER

TIMER

AS2591

16

16

LCD

S1_n

S2_n

Figure 1: Block diagram

Rev. 1.0 Page 1 May 1999

Preliminary AS2591

Pin Description

Pin # Name Type Description

1
2
3
4
5
6
7
8

9
10
11
12

S2_10
S1_10
S2_11
S1_11
S2_12
S1_12
S2_13
S1_13
S2_14
S1_14
S2_15
S1_15

AO

13 CS DI

14 DI DI

15 SCLK DI

16 V

DD

Supply

Segment Outputs

Output pins for driving segments of LCD.

Chip Select

Chip select signal from CPU (e.g. AS2525).

Data Input

Data input pin for serial interface.

Serial Clock Input

Clock input pin for serial interface.

Positive Voltage Supply

This pin is the positive power supply for the device.

17 V

18
19

20 V

21
22
23
24

Continues…

SS

XTAL1
XTAL2

LCD

COM1
COM2
COM3
COM4

Supply

AI

AO

Negative Voltage Supply

This pin is the negative power supply for the device.

Oscillator Pins

Oscillator pins for connection of a 32.768 kHz crystal.

LCD Reference Voltage

This is the input pin for setting the internal LCD reference voltage (see
also Figure 4: Supply arrangement).

Backplane Outputs

Ouput pins for driving backplanes of LCD.

Rev. 1.0 Page 2 May 1999

Preliminary AS2591

S1_9

S2_9

S1_8

S2_8

S1_7

S2_7

S1_6

S2_6

S1_5

S2_5

S1_4

S1_15

CS

DI

SCLK

V

DD

V

SS

XTAL1

XTAL2

V

LCD

COM1

COM2

Pin # Name Type Description

25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44

DI: Digital Input AI: Analogue Input
DO: Digital Output AO: Analogue Output
DI/O: Digital Input/Output AI/O: Analogue Input/output

S2_0
S1_0
S2_1
S1_1
S2_2
S1_2
S2_3
S1_3
S2_4
S1_4
S2_5
S1_5
S2_6
S1_6
S2_7
S1_7
S2_8
S1_8
S2_9
S1_9

AO

Segment Outputs

Output pins for driving segments of LCD.

Pin Configuration

S2_10
S1_10
S2_11
S1_11
S2_12
S1_12
S2_13
S1_13
S2_14
S1_14
S2_15

1

6

39

AS2591

17

Figure 2: Pin configuration

S2_4
S1_3
S2_3
S1_2
S2_2

28

S1_1
S2_1
S1_0
S2_0
COM4
COM3

Rev. 1.0 Page 3 May 1999

Preliminary AS2591

Typical Application

Figure 3: Typical Application

See also application note AN525 for further information.

Rev. 1.0 Page 4 May 1999

Preliminary AS2591

Functional Description

AS2591 is a CMOS mixed-mode integrated circuit for
driving LCDs with 4 backplanes and 24 or 31
segments providing 12 or 16 7-segment digits and 12
symbols. The device is controlled via a simple 2-wire
bus and a chip-select signal. The device also
includes an elapse-time counter which is started 5
seconds after power-up and incremented every
second.

The timer is re-started whenever the device gets a
WRITE-DIGIT or SHIFT&WRITE command within the
first 5 counts (except commands for displaying digits

o

", "o"). The content of the timer is displayed 5

"-", "
second after receiving the last WRITE-DIGIT,
SHIFT&WRITE or BLINKING command. The normal
display appears immediately after receiving a WRITE­DIGIT, SHIFT&WRITE, or BLINKING command.

Supply Arrangement

The device is supplied through VDD. The internal
reference voltages (V33, V23, and V13) for the backplane
and segment outputs are set at pin V
to 3.27V the segment output voltage is 2.97V
(middle).

. With V

LCD

LCD

set

This voltage can be programmed through the serial
bus to 2.83V (low) or 3.09V (high) for optimising the
contrast of the LCD. The 1/3, 2/3, and 3/3 voltages
are generated internally (see Figure 4: Supply
arrangement). In applications with varying VDD, it is
recommended to insert a voltage regulator at V
order to assure a constant contrast (see also
application note AN525 for further information).

From

AS2525

Figure 4: Supply arrangement

VDD

V

LCD

VSS

Contrast

control

VDD

in

LCD

Contrast
control

V

33

V

23

V

13

LCD Digit Code

Code [HEX]:

Number:

Display:

Code [HEX]:

Letters/Signs:

Display:

Code [HEX]:

Letters/Signs:

Display:

01 02 03 04 05 06 07 08 09 00

1 2 3 4 5 6 7 8 9 0

|
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_
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|_

_
_|
_|

|_|
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_
|_
_|

_
|_
|_|

_
|
|

_
|_|
|_|

_
|_|
_|

_
| |
|_|

0A 0B 0C 0D 0E 0F 10 11 12 13 14

a b c d e f # * - ( )

_
|_|
| ||_|_| _|_

_|
|_|

_
|_
|_

_
|_
|

_
_ _|_

|

_ _|

|_

_
|
_|

15 16 17 18 19 1A 1B 1C 1D 1E 1F

H I L N O P R T U "

|_|
| | |||_ _| | _|_|

_
|_|| _||_

|_ |_|

_
|_|

Rev. 1.0 Page 5 May 1999

Preliminary AS2591

C3C2C1D4D3D2D1D0MSB

LSB

LCD Symbols

Each symbol is associated with a fixed digit address. The circuit has 12 symbols implemented associated with the
lower 12 addresses.

Table 1: Symbol Overview

Enabled Address Name Description

Always y0

Optional y1 SP Loudspeaker on

Always y2
Optional y3 MF DTMF dialling mode selected
Optional y4 LD Loop disconnect (pulse) dialling mode selected
Optional y5 Vol Volume control keys activated. Remains on 2 seconds after last volume

Always y6

Always y7

Always y8

Optional y9 - Not used
Optional y10 RD Indicates that last number redial has been activated

Always y11

Symbol data are not effected by a BLINKING or by a WRITE&SHIFT command. Symbols will be displayed
independently from selecting the upper bank of the 32 digit buffer to be displayed.

KL

MT

MR
BO
SH

PG

Key lock activated

Mute activated

key pressure
Memory redial key has been pressed. Remains on until next key pressure
Bell off. Indicates that ringer has been turn off.
Shift; indicates that shift key has been pressed. Remains on untill next key

pressure

Indicates program mode

The symbol displayed depends on the layout of the LCD display. If the layout of the 12/16 digit LCD displays can
be done similar, the symbol mapping does not need to be stored in the EEPROM.

Serial Interface

The serial interface uses the pins CS (chip select), SCLK (serial clock line), and DI (data input). A frame consists of
a 3-bit command and 5-bit data (see Figure 5: Frame of serial interface). Commands are executed self-timed by
the internal clock and commence at the falling edge of the CS signal.

CS

SCLK

DI

Figure 5: Frame of serial interface

Rev. 1.0 Page 6 May 1999

Preliminary AS2591

Table 2: Commands

Command

[bin]

000 address Set pointer to address. If address is > 16/12, the upper bank of the 32-digit buffer

001 digit_code Write digit code to active address.
010 digit_code Shift & write digit code to address 0 (right most digit). Address pointer is set to 0..
011 1xBFS Blinking ON at address:

100 1xxxx Symbol ON at address

101 00xxx Clear all digits, symbols, blinking, reset address to 0

Data

[bin]/name

0xxxx Blinking OFF at address

0xxxx Symbol OFF at address

10xxx Clear all digits, blinking, reset address to 0

Description

will be displayed. In case of a 12-digit display, up to address 23 will be displayed,
and if address is > 24 a third bank up to 32 will be displayed (see Table 4: 12-digit
display and Table 5: 16-digit display).

BF blinking frequency S enabled/disabled
00 1.33 Hz 0 blinking
01 2.00 Hz 1 static off
10 0.67 Hz
11 1.00 Hz

01xxx Hide elapse time for 5 seconds.

11xxx Hide elapse time permanently (note: Hide is reset by above command 101 01xxx).
110 xxFTM Reserved for test modes
111 0xZxx Display OFF and Cleared.

Z delay time
0 5 seconds
1 no delay

1CCND Display ON (resets the off timer)

CC contrast voltage ND number of digits
00 low 00 12 digits

01 middle 01 16 digits
10 high 10 not allowed
11 not allowed 11 not allowed

Rev. 1.0 Page 7 May 1999

Preliminary AS2591

Digit Layout

COM1 - 4 = common backplane signals
S1_n, S2_n = segment signals

a

b

f

g

e

c

d

yn

Figure 6: Digit Layout

n = 0 is most right digit, n= 11 is most left digit for 12-digit displays,
and n = 15 is most left digit for 16-digit displays.

Table 3: Backplanes and segments

COM1 COM2 COM3 COM4

S1_n a f e yn
S2_n b g c d

Segment Allocation

Table 4: 12-digit display

Symbol Address y11 y10 y9 y8 y7 y6 y5 y4 y3 y2 y1 y0

AS2525

PG

RD -

Digits Normal 11 10 9 8 7 6 5 4 3 2 1 0

Upper 1 23 22 21 20 19 18 17 16 15 14 13 12

SH BO MR

Vol LD MF

MT

SP

KL

Upper 2 31 30 29 28 27 26 25 24

Table 5: 16-digit display

Symbol Addr. y11 y10 y9 y8 y7 y6 y5 y4 y3 y2 y1 y0
AS2525

PG

RD -

SH BO MR

Vol LD MF

MT

SP

KL

Digits Normal 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Digits Upper 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16

The symbols in bold are always enabled and other symbols can be enabled through the serial interface. Symbols
will be displayed independently from selecting the upper bank of the 32 digit buffer to be displayed.

The AS2591 incorporates a buffer for 32 digits. Digits are entered from the most right position and shifted left by
new entries (see also Table 2: Commands).

Rev. 1.0 Page 8 May 1999

Preliminary AS2591

Electrical Characteristics

Absolute Maximum Ratings*

Supply Voltage ................................................................ ............................................................... -0.3 ≤ V

Input Current ................................................................................................ ..........................................+/- 25 mA

≤ V

Input Voltage.....................................................................................................................-0.3V

≤ V

IN

Electrostatic Discharge...........................................................................................................................+/- 1000V

Storage Temperature Range........................................................................................................... -65 to +125°C

Total Power Dissipation ............................................................................................................................500mW

*Exceeding these figures may cause permanent damage. Functional operation under these conditions is not permitted.

Recommended Operating Range

Symbol Parameter Conditions Min. Typ. Max. Units

DD

+ 0.3V

DD

≤ 7V

V

DD

V

LCD

T

AMB

f

OSC

Operating Voltage 3.2 4.0 4.8 V
LCD Reference Voltage 2.5 3.0 3.5 V

Ambient Operating Temp. Range -25 +70 °C
Oscillator Frequency 32.768 kHz

DC Characteristics

Recommended operating conditions unless otherwise specified.

Symbol Parameter Conditions Min. Typ.* Max. Units

I

DD

I

DD0

V

33

V

IL

Operating Supply Current Unloaded 150 µA
Idle Current Idle mode, oscillator not running 1 µA
Contrast Output Voltage at

V

LCD

= 3.27V

COM1-4 and S1-2_n Pins

Contrast voltage low
Contrast voltage middle
Contrast voltage high

Input Low Voltage V

SS

2.83

2.97

3.09

V
V
V

0.3 VDDV

V

IH

Input High Voltage 0.7 V

DD

V

V

DD

* Typical figures are at 25°C and are for design aid only; not guaranteed and not subject to production testing.

Rev. 1.0 Page 9 May 1999

Preliminary AS2591

Electrical Characteristics

Recommended operating conditions unless otherwise specified.

Symbol Parameter Conditions Min. Typ. Max. Units

F

LCD

t

OFF-TIMER

f

BLINK

R

COM

LCD Frame Frequency 61 64 67 Hz
Off Timer 4.75 5 5.25 sec
Blinking Frequency BF = 00

Output Impedance of
Backplane Outputs

R

SEG

Output Impedance of
Segment Outputs

Package Outline

44 Pin TQFP

See Package Catalogue

BF = 01
BF = 10
BF = 11

1.33

2.00

0.67

1.00

Hz
Hz
Hz
Hz

150 kohm

150 kohm

Devices sold by Austria Mikro Systeme Int. AG are covered by the warranty and patent indemnification provisions appearing in
its Term of Sale. Austria Mikro Systeme Int. AG makes no warranty, express, statutory, implied, or by description regarding
the information set forth herein or regarding the freedom of the described devices from patent infringement Austria Mikro
Systeme Int. AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to
designing this product into a system, it is necessary to check with Austria Mikro Systeme Int. AG for current information. This
product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual
environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment
are specifically not recommended without additional processing by Austria Mikro Systeme Int. AG for each application.

Copyright © 1999, Austria Mikro Systeme International AG, Schloss Premstätten, 8141 Unterpremstätten, Austria.
Trademarks Registered®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated,
stored, or used without the prior written consent of the copyright owner.

Austria Mikro Systeme Int. AG reserves the right to change or discontinue this product without notice.

Rev. 1.0 Page 10 May 1999