Data Sheet

AS2590

Rev. 1

Dec. 1993

LC DISPLAY DRIVER WITH 18 DIGITS,

6 SYMBOLS AND CLOCK/TIMER

Austria Mikro Systeme International

KEYBOARD

Vss

DIALLER

CONTROLLER

AS2574A/B

SDA

SCL

V23

V13

LCD

BIAS

Vss

AS2590

32.768kHz

SPEECH CIRCUIT

Key Features

Very low operating current, typ. 30

A @ 3V

Low power oscillator using 32.768 kHz Xtal

2-wire interface compatible to AS2574B

18 digits by 7 segments

6 symbols

24 hour clock showing hours and minutes

Timer automatically showing elapsed time in

minutes and seconds after each telephone

conversation

33 LCD segment outputs and 4 LCD backplane

outputs

4 times multiplex mode with a cycle time of 128 Hz

Mode select pin for selecting clock function

General Description

The AS2590 is an integrated CMOS device for driving a

liquid crystal display intended for use in telephones. The

2-wire serial interface is compatible to the dialler

AS2574B.

The extreme low operating current allows the circuit to

be operational also during on-hook which is necessary

in order to the use of the clock function. In on-hook

condition the circuit can be supplied by a small leakage

current from the telephone line or from a small 3V

battery.

Whether the oscillator shall continue operating or be

stopped during on-hook is determined by the mode pin,

MS.

Package

Available in 48 pin DIP and 52 pin PLCC.

Data Sheet

AS2590

Rev. 1

Dec. 1993

Pin Description

DIL

PLCC

Symbol

Function

BP1

Blackplanes

BP0

Segment outputs

V1/3

1/3 of V

pin for external voltage divider

S10

Segment outputs

S11

S12

S13

S14

S15

S16

S17

S18

S19

Negative supply pin

BP3

Back plane outputs

BP2

V2/3

2/3 of V

pin for external voltage divider

S32

Segment outputs

S31

S30

S29

S28

S27

S26

S25

S24

S23

S22

S21

S20

LCD

Negative supply pin for LC display

Data Sheet

AS2590

Rev. 1

Dec. 1993

Pin Description Continued

DIL

PLCC

Symbol

Function

SDA

Serial data line input to dialler/controller

SCL

Clock line input of serial data link

BIAS

Oscillator bias input, recommended bias resistor 2.2 M

XTAL1

Oscillator pins for 32.768 kHz crystal, a resistor and two capacitors

XTAL2

Mode select input:

MS = V

> clock/timer disabled

MS = V

> clock/timer enabled

Positive supply pin

Digit Description

Segment

numbers

on on on on on on

0...9

on on

on on on on

on on

on on on on on

on on on

on on on on on on on

on on on

on on

letter A

on on on

letter B

on on on on on

letter C

on on

Letter D

on on on on

underscore

asterisk

on on

hash

on on on

pause

P/T

temp. MF

recall

LCD Layout

Figure 2

SB3

SB5

SB4

SB2

SB0

SB1

Figure 1

Table 1 Segments Digits

SB0 = loudspeaker on (blinking with 1 Hz)

SB1 = microphone muted (blinking with 1 Hz)

SB2 = 2nd key function enabled

SB3 = number stored

SB4 = number buffered in FIFO, not stored

SB5 = colon for clock and timer (blinking when clock is

shown)

Data Sheet

AS2590

Rev. 1

Dec. 1993

Description

Operating Modes
The following two operating modes are pin selectable:

Mode 0:
Clock and timer are disabled and the oscillator is stopped
when going on-hook (command BLANK ALL).

Mode 1:
Clock and timer functions are enabled, clock is displayed
both during off- and on-hook (assuming that clock is set).
When going from off-hook to on-hook, the timer content
(elepsed time) is displayed for 6 seconds (assuming that
a start timer command was received).

Clock
After a power up reset the clock is disabled. The clock
will not be displayed until a valid set clock procedure has
been performed (mode 1 only). The format of the clock
is hh:mm and the leading zero of the hours is suppressed
and symbol 5 (:) is blinking with a frequency of 1 Hz. The
timer is running when off-hook and displayed for 6
seconds when going on-hook. The content of the timer
(elapsed time) is shown in stead of the clock in the format
mm:ss.

If a SET CLOCK command is received the display is
blanked, four underscore symbols are displayed where
the 4 digits of the clock will be entered (the 4 most right
digits) and symbol 5 is turned on (_ _ : _ _). The next 4
data words are interpreted as the time (hh mm). The
fourth digit terminates the SET CLOCK and starts the
clock with the seconds set to zero.

If less than 4 data words (digits) are received the first
command (normally a BLANK DIGITS or a BLANK ALL)
will terminate the SET CLOCK. But as the procedure
was incomplete, it is regarded as invalid and further
clock display is disabled. The next valid SET CLOCK
command will enable the clock again. The SET CLOCK
command does not effect the timer.

The time-out condition (approx. 15 seconds) when setting
clock is recognized by the dialler/controller (e.g. AS2574).
If a time-out condition occours the dialler sends a
BLANK ALL command to terminated the SET CLOCK.

Timer
The following commands effect the timer:

- START TIMER and START FIFO; they start the timer.

If the timer is already running, it cannot be restarted
by one of these commands before stopping the timer
with the BLANK ALL command.

- Power up; enables subsequent start timer commands.

- BLANK ALL; clears the whole display (including special

symbols) and displays the timer contents for 6 seconds
(if clock/timer function is enabled) or until a new
START TIMER/FIFO command is received. Then it
returns to normal display mode.

- if any command or data is received by the serial

interface within the time out period after a BLANK ALL
command, the timer display will be blanked or replaced
by the clock display.

The timer is displayed in the format mm:ss with the
leading zero of the minutes suppressed and symbol 5 (:)
turned on.

LCD Outputs
The 33 segment outputs and 4 backplane outputs can
drive a customized liquid crystal display in 1:4 multiplex
mode. Two reference voltages V1/3 and V2/3 are
provided by an external voltage divider.

Digits and Special Symbols
The display consists of 18 seven segment digits and 6
special symbols (see figure 1):

- D0...D17; D0 is the most left seven segment digit, the

possible numbers displayed by one digit are shown in
figure 2. The symbol (_) is only displayed at D13, D14,
D16 and D17 when setting the clock.

- SB0...SB5; 6 special symbols (one segment for each

symbol only), see figure 1 for reference. If SB0
(loudspeaker on) or SB1 (microphone muted) are
turned on, they blink with a frequency of 1 Hz.

Multiplex Mode
A total of 132 segments are addressable. One output
drives 4 segments in a time multiplex mode. The 4
backplane outputs determine the currently addressed
segment (see figure 3).

Figure 3 gives the correlation between segment outputs
and addressed segments.

Data and Commands
32 different words may be received via the serial interface.
19 words are interpreted as display data for one of the
18 seven segment digits. Table 2 gives the translation
from received code to displayed symbol.

13 words are valid commands codes. The function of
each command is described in table 2, and table 4 lists
the 5 bit codes for all possible commands.

Data Sheet

AS2590

Rev. 1

Dec. 1993

Table 2 Command Summary

MNEMONIC

FUNCTION

SET LS

Turns on special symbol SB0 (loudspeaker on, blinking)

CLEAR LS

Turns off special symbol SB0

SET MUTE

Turns on special symbol SB1 (microphone muted, blinking)

CLEAR MUTE

Turns off special symbol SB1

SET 2ND

Turns on special symbol SB2 (2nd function on keyboard)

CLEAR 2ND

Turns off special symbol SB2

SET CLOCK

Initiates clock setting; SB5 is turned on

START

Blanks all digits, SB3 and SB4; accepts data, timer not started

START COPY

Blanks all digits and SB4; turns on SB3, accepts data, timer not started (if not

already running)

START FIFO

Blanks all digits and SB3; turns on SB4, accepts data, timer started (if not

already running)

START TIMER

Blanks all digits, turns off SB3 and SB4, accepts data, timer started (if not

already running)

BLANK ALL

Blanks all digits and all special symbols (except D13, D14, D16, D17 and SB5

when clock is running)

TEST MODE

Turns circuit into test mode

Table 3 Segment Mapping

SEGMENT

BACKPLANE

OUTPUT

BP0

BP1

BP2

BP3

SB0

SB1

SB4

SB2

D0/F

D0/G

D0/E

D0/D

D0/A

D0/B

D0/C

D1/D

D1/F

D1/G

D1/E

D1/C

D1/A

D1/B

D2/G

D2/E

D2/A

D2/F

D2/B

D2/C

D3/A

D3/F

D2/E

D2/D

D3/B

D3/G

D3/C

D3/D

D4/F

D4/G

D4/E

D4/D

D4/A

D4/B

D4/C

D5/D

S10

D5/F

D5/G

D5/E

D5/C

S11

D5/A

D5/B

D6/G

D6/E

S12

D6/A

D6/F

D6/B

D6/C

S13

D7/A

D7/F

D7/E

D6/D

S14

D7/B

D7/G

D7/C

D7/D

S15

D8/F

D8/G

D8/E

D8/D

S16

D8/A

D8/B

D8/C

D9/D

SEGMENT

BACKPLANE

OUTPUT

BP0

BP1

BP2

BP3

S17

D9/F

D9/G

D9/E

D9/C

S18

D9/A

D9/B

D10/G

D10/E

S19

D10/A

D10/F

D10/B

D10/C

S20

D11/A

D11/F

D11/E

D10/D

S21

D11/B

D11/G

D11/C

D11/D

S22

D12/F

D12/G

D12/E

D12/D

S23

D12/A

D12/B

D12/C

D13/D

S24

D13/F

D13/G

D13/E

D13/C

S25

D13/A

D13/B

D14/G

D14/E

S26

D14/A

D14/F

D14/B

D14/C

S27

D15/A

D15/F

D15/E

D14/D

S28

D15/B

D15/G

SB5

D15/D

S29

D16/F

D16/G

D16/E

D16/D

S30

D16/A

D16/B

D16/C

D17/D

S31

D17/F

D17/G

D17/E

D17/C

S32

D17/A

D17/B

D15/C

SB3

Dn/m = segment m of digit n

SBn = special symbol n

Data Sheet

AS2590

Rev. 1

Dec. 1993

BP0

BP1

BP2

BP3

2/3

1/3

Vss

2/3

1/3

Vss

2/3

1/3

Vss

2/3

1/3

Vss

2/3

1/3

Vss

2/3

1/3

Vss

Active Backplane

BP0

BP1

BP2

BP3

off

to high transition of the data line while the clock line is
high followed by a negative clock pulse indicates a stop
condition (see figure 4).

SDA

SCL

START

LSB

MSB

STOP

WORD

GAP

START

Figure 4 Interface Timing

Serial Interface
The serial interface is a one way, two line link between
the dialler (AS2574) and the display driver. The two lines
are the serial data line (SDA) and the serial clock line
(SCL). The display driver can only receive data.

Word Transfer:
Data are transferred as 5 bit words with start and stop bit.
the least significant bit is sent first after the start bit. As
long as there is no data transfer, both data and clock
lines have to remain high. Also between two words both
lines have to stay high for a specified time. Figure 4
shows the timing of the serial interface.

Start and Stop Conditions:
A start condition is detected when the data line goes
from high to low while the clock line is held high. A low

Figure 3 LCD driver outputs

Table 4 Codes for Serial Interface

NO SYMBOL MSB

LSB HEX

SB0-on

SB0-off

SB1-on

SB1-off

SB2-on

SB2-off

SET CLOCK

START

COPY

FIFO

TIMER

BLANK

TEST

P/T

Data Sheet

AS2590

Rev. 1

Dec. 1993

Electrical Characteristics

Absolute Maximum Ratings

Positive Supply Voltage ...................................................................................................................-0.3V

Input Current ................................................................................................................................................

25 mA

Digital Input Voltage .....................................................................................................V

- 0.3V

+ 0.3V

Electrostatic Discharge (HBM) ........................................................................................................................

500V

Storage Temperature ......................................................................................................................-65

C to +125

Recommended Operating Conditions

Supply Voltage ..............................................................................................................................2.5V

5.5V

Oscillator Frequency ...............................................................................................................................32.768 kHz

Operating Temperature ....................................................................................................................- 25

C to +70

DC Characteristics (Default conditions: recommended operating conditions; outputs unloaded; V

= 3.0V)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

Test circuit fig. 5

DD0

Standby Current

no clock running

1.5

Operating Current

AMB

= 5 to 55

Note 1, note 2

Input Voltage, Low

0.2 V

Line Voltage, High

0.8 V

LCD

Output Voltage, Sink

LCD

= 4.8 mA

0.4

BIAS

Oscillator Bias Resistor

2.2

Note 1: Segment and backplane outputs loaded with maximum 30 pF, power consumption of external voltage divider not

included, R

BIAS

= 2.2 M

10%.

Note 2: Xtal parameters:

Rimax = 60 k

(Rityp = 30 k

)

Qmin = 35 000
Co = 1.5 pF (capacitance across Xtal terminals)
fxtal = 32.768 kHz

Data Sheet

AS2590

Rev. 1

Dec. 1993

SDA/SCL

Serial Interface

Fig. 5

Clock Frequency

kHz

CLH

Clock High Time

CLL

Clock Low Time

Clock Low to Data Change

CLL

SOH

Stop Bit High Time

SOL

Stop Bit Low Time

Data Hold Time

200

SUSO

Clock Setup for Stop

200

HSA

Clock Hold for Start

200

GAP

Data High between 2 Words

100

BP0...3

Back Plane Outputs

Figure 6, note 1

BRON

Rise Time, on

BFON

Fall Time, on

BROF

Rise Time, off

BFOF

Fall Time, off

Cycle Frequency

128

S0...32

Segment Outputs

Figure 7, note 2

SRON

Rise Time, on

SFON

Fall Time, on

SROF

Rise Time, off

SFOF

Fall Time, off

Cycle Frequency

128

TIMER

Timer Display Time

Note 3

sec

XUP

Oscillator Startup Time

BIAS

= 2.2 M

300

AC Characteristics (V

= 3.0V; T

AMB

= -25 to 70

C, unless otherwise specified)

Symbol

Parameter

Conditions

Min

Typ

Max

Units

Note 1: Loads on backplanes = 3 000 pF//10 M

Note 2: Loads on segments = 360 pF//1 M

Note 3: After BLANK ALL command and timer has been started with a valid start command, timer content is displayed.

Data Sheet

AS2590

Rev. 1

Dec. 1993

Pin Configurations

48 Pin DIP

AS2590

XTAL2

XTAL1

BIAS

SCL

SDA

LCD

S20

S21

S22

S23

S24

BP1

BP0

V1/3

S10

S25

S11

S12

S13

S14

S15

S16

S17

S18

S19

Vss

S26

S27

S28

S29

S30

S31

S32

V2/3

BP2

BP3

52 pin PLCC

Ordering Information:

48 pin DIP:

AS2590 P

52 pin PLCC:

AS2590 N

Applications:

For application support contact your local AMS sales
offices.

AS2590

BP0

BP1

XTAL2

XTAL1

BIAS

SCL

NC
SDA
V

LCD

S20
S21
S22
S23
S24
S25
S26
S27
S28
S29

S4
S5
S6
S7
S8
S9

V1/3

S10
S11
S12
S13
S14

S15

S16

S17

S18

S19

BP3

BP2

V2/3

S32

S31

S30

Data Sheet

AS2590

Rev. 1

Dec. 1993

Sales Representative

Devices sold by Austria Mikro Systeme are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. Austria Mikro Systeme 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 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 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 for each application.

1993, Austria Mikro Systeme International AG, Schloss Premstätten, 8141 Unterpremstätten, Austria. Trademarks Registered

reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner.

The information furnished here by Austria Mikro Systeme is believed to be correct and accurate. However, Austria Mikro Systeme shall not be liable to recipient or any third party for any damages,
including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection
with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of Austria Mikro Systeme rendering
of technical or other services.

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