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Preliminary
AS2591
16-Digit LCD Driver CMOS Integrated Circuit
Austria Mikro Systeme International AG
Key Features
q 16-digit LCD driver on a 44 pin CMOS chip q Operating voltage range: 3.2 to 4.8V q Low power consumption: max. 150 A q Driving 7-segment displays with up to 16 digits and 12 symbols q Option for 12 digits q Buffer for 32 digits q 4 backplanes q 2-wire interface q On chip timer for showing elapsed time q Contrast adjustable q On chip oscillator using 32.768 kHz crystal q Compatible with AS2525
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.
Block Diagramme
VDD POR DI SCLK CS
DATA
BACKPLANE COUNTER
4
COM1-4
SERIAL I/F
7SEGMENT DECODER SEGMENT MULTIPLEXER DIGIT MEMORY 32 DIGITS 16 S1_n
LCD
COMMAND ADDRESS DECODER CONTROL
16
S2_n
32.768 kHz OSC ELAPSE TIME COUNTER
TIMER VLCD CONTRAST VOLTAGE CONTROL
AS2591
Figure 1: Block diagram
Rev. 1.0
Page 1
May 1999
Preliminary
Pin Description
Pin # 1 2 3 4 5 6 7 8 9 10 11 12 13 Name S2_10 S1_10 S2_11 S1_11 S2_12 S1_12 S2_13 S1_13 S2_14 S1_14 S2_15 S1_15 CS Type AO Description Segment Outputs Output pins for driving segments of LCD.
AS2591
DI
Chip Select Chip select signal from CPU (e.g. AS2525).
14
DI
DI
Data Input Data input pin for serial interface.
15
SCLK
DI
Serial Clock Input Clock input pin for serial interface.
16
VDD
Supply
Positive Voltage Supply This pin is the positive power supply for the device.
17
VSS
Supply
Negative Voltage Supply This pin is the negative power supply for the device.
18 19 20
XTAL1 XTAL2 VLCD AI
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).
21 22 23 24 Continues...
COM1 COM2 COM3 COM4
AO
Backplane Outputs Ouput pins for driving backplanes of LCD.
Rev. 1.0
Page 2
May 1999
Preliminary
Pin # 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44
DI: DO: DI/O:
AS2591
Type AO Description Segment Outputs Output pins for driving segments of LCD.
Name 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
Digital Input Digital Output Digital Input/Output
AI: AO: AI/O:
Analogue Input Analogue Output Analogue Input/output
Pin Configuration
S2_10 S1_10 S2_11 S1_11 S2_12 S1_12 S2_13 S1_13 S2_14 S1_14 S2_15
S1_9 S2_9 S1_8 S2_8 S1_7 S2_7 S1_6 S2_6 S1_5 S2_5 S1_4
39
1
6
AS2591
28
17
S2_4 S1_3 S2_3 S1_2 S2_2 S1_1 S2_1 S1_0 S2_0 COM4 COM3
Figure 2: Pin configuration
Rev. 1.0
S1_15 CS DI SCLK VDD V SS XTAL1 XTAL2 VLCD COM1 COM2
Page 3
May 1999
Preliminary
Typical Application
AS2591
Figure 3: Typical Application
See also application note AN525 for further information.
Rev. 1.0
Page 4
May 1999
Preliminary
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.
AS2591
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 VLCD in order to assure a constant contrast (see also application note AN525 for further information).
From AS2525 VDD VDD
VLCD
VSS
Contrast control
Contrast control V33 V23
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 VLCD. With VLCD set to 3.27V the segment output voltage is 2.97V (middle).
V13
Figure 4: Supply arrangement
LCD Digit Code
Code [HEX]: Number: Display:
01 1 | |
02 2 _ _| |_
03 3 _ _| _|
04 4 |_| |
05 5 _ |_ _|
06 6 _ |_ |_|
07 7 _ | |
08 8 _ |_| |_|
09 9 _ |_| _|
00 0 _ || |_|
Code [HEX]: Letters/Signs:
0A a _ Display: |_| ||
0B b |_ |_|
0C c _ |_
0D d _| |_|
0E e _ |_ |_
0F f _ |_ |
10 # _ _ _
11 * |_ |
12 _
13 ( _ | |_
14 ) _ | _|
Code [HEX]: Letters/Signs:
15 H
16 I
17 L | |_
18 N _ ||
19 O _ |_|
Display: |_| ||
|
1A P _ |_| |
1B R _ |
1C T |_ |_
1D U
1E " _ |_|
1F
|_|
Rev. 1.0
Page 5
May 1999
Preliminary
LCD Symbols
AS2591
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 Always Optional Always Optional Optional Optional Always Always Always Optional Optional Always Address y0 y1 y2 y3 y4 y5 y6 y7 y8 y9 y10 y11 Name KL SP MT MF LD Vol MR BO SH RD PG Description Key lock activated Loudspeaker on Mute activated DTMF dialling mode selected Loop disconnect (pulse) dialling mode selected Volume control keys activated. Remains on 2 seconds after last volume 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 Not used Indicates that last number redial has been activated Indicates program mode
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. 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 C3 C2 MSB C1 D4 D3 D2 D1 D0 LSB
Figure 5: Frame of serial interface
Rev. 1.0
Page 6
May 1999
Preliminary
Table 2: Commands Command [bin] 000 Data [bin]/name address Description
AS2591
Set pointer to address. If address is > 16/12, the upper bank of the 32-digit buffer 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). Write digit code to active address. Shift & write digit code to address 0 (right most digit). Address pointer is set to 0.. Blinking ON at address: BF 00 01 10 11 blinking frequency 1.33 Hz 2.00 Hz 0.67 Hz 1.00 Hz S 0 1 enabled/disabled blinking static off
001 010 011
digit_code digit_code 1xBFS
0xxxx 100 1xxxx 0xxxx 101 00xxx 10xxx 01xxx 11xxx 110 111 xxFTM 0xZxx
Blinking OFF at address Symbol ON at address Symbol OFF at address Clear all digits, symbols, blinking, reset address to 0 Clear all digits, blinking, reset address to 0 Hide elapse time for 5 seconds. Hide elapse time permanently (note: Hide is reset by above command 101 01xxx). Reserved for test modes Display OFF and Cleared. Z 0 1 delay time 5 seconds no delay
1CCND
Display ON (resets the off timer) CC 00 01 10 11 contrast voltage low middle high not allowed ND 00 01 10 11 number of digits 12 digits 16 digits not allowed not allowed
Rev. 1.0
Page 7
May 1999
Preliminary
Digit Layout
a f g e d yn c b
AS2591
COM1 - 4 = common backplane signals S1_n, S2_n = segment signals 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 S1_n S2_n a b COM2 f g COM3 e c COM4 yn d
Figure 6: Digit Layout
Segment Allocation
Table 4: 12-digit display Symbol Address AS2525 Digits Normal Upper 1 Upper 2 y11 PG 11 23 y10 RD 10 22 y9 9 21 y8 SH 8 20 y7 BO 7 19 31 y6 MR 6 18 30 y5 Vol 5 17 29 y4 LD 4 16 28 y3 MF 3 15 27 y2 MT 2 14 26 y1 SP 1 13 25 y0 KL 0 12 24
Table 5: 16-digit display Symbol Addr. AS2525 Digits Normal Digits Upper 15 31 14 30 13 29 12 28 y11 PG 11 27 y10 RD 10 26 y9 9 25 y8 SH 8 24 y7 BO 7 23 y6 MR 6 22 y5 Vol 5 21 y4 LD 4 20 y3 MF 3 19 y2 MT 2 18 y1 SP 1 17 y0 KL 0 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 VDD 7V Input Current..........................................................................................................................................+/- 25 mA Input Voltage.....................................................................................................................-0.3V VIN VDD + 0.3V Electrostatic Discharge...........................................................................................................................+/- 1000V Storage Temperature Range........................................................................................................... -65 to +125C Total Power Dissipation ............................................................................................................................ 500mW
*Exceeding these figures may cause permanent damage. Functional operation under these conditions is not permitted.
Recommended Operating Range
Symbol VDD V
LCD
Parameter Operating Voltage LCD Reference Voltage Ambient Operating Temp. Range Oscillator Frequency
Conditions
Min. 3.2 2.5 -25
Typ. 4.0 3.0
Max. 4.8 3.5 +70
Units V V C kHz
TAMB fOSC
32.768
DC Characteristics
Recommended operating conditions unless otherwise specified. Symbol IDD IDD0 V33 Parameter Operating Supply Current Idle Current Contrast Output Voltage at COM1-4 and S1-2_n Pins Conditions Unloaded Idle mode, oscillator not running VLCD = 3.27V Contrast voltage low Contrast voltage middle Contrast voltage high VSS 0.7 VDD 2.83 2.97 3.09 V V V 0.3 VDD V VDD V Min. Typ.* Max. 150 1 Units A A
VIL VIH
Input Low Voltage Input High Voltage
* Typical figures are at 25C 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 FLCD tOFF-TIMER fBLINK Parameter LCD Frame Frequency Off Timer Blinking Frequency BF = 00 BF = 01 BF = 10 BF = 11 Conditions Min. 61 4.75 Typ. 64 5 1.33 2.00 0.67 1.00 150 150 Max. 67 5.25 Units Hz sec Hz Hz Hz Hz kohm kohm
RCOM RSEG
Output Impedance of Backplane Outputs Output Impedance of Segment Outputs
Package Outline
44 Pin TQFP
See Package Catalogue
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 (c) 1999, Austria Mikro Systeme International AG, Schloss Premstatten, 8141 Unterpremstatten, Austria. Trademarks Registered(R). 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

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