bl55021.pdf

BL55021

http://www.belling.com.cn - 1 - 8/11/2006

Total 8 Pages Wrote by 2006

LCD Driver for 128 Display Units BL55021

1 General Description

The BL55021 is a 128 pattern (32x4), memory mapping, and multi-function LCD driver.

The S/W configurationfeature of the BL55021 makes it suitable for multiple LCD

applications including LCD modules and display subsystems. Only three or four lines are

required for the interface between the host controller and the BL55021. The BL55021

contains a power down command to reduce power consumption.

2 Features � Operating voltage: 2.4V~5.2V

� Built-in 256kHz RC oscillator

� External 32.768kHz crystal or 256kHz frequency source input

� Selection of 1/2 or 1/3 bias, and selection of 1/2 or 1/3 or 1/4 duty LCD applications

� Built-in time base generator and WDT

� 8 kinds of time base/WDT clock sources

� Two selectable tone frequencies (2kHz/4kHz)

� 32 X 4 LCD driver

� Built-in 32x4 bit display RAM

� 3\4 line serial data interface

� Software configuration feature

� R/W address auto increment

� VLCD for adjusting LCD operating voltage

� 48-pin SSOP package

3 Pin Assignment 4 Pin Description

Pin NO. Pin Name Pin Function 9 CS Chip Selection 10 READ Signal output control(RD) 11 CPW Write Control Pulse(WR) 12 DI Serial DATA Line 13 Vss Minus power terminal

14、15 CPO、CPI Clock Pulse Out/In(OSC) 16 Vlcd LCD power source 17 Vdd Plus power terminal 18 TIS Test Interrupt

19,20 TB1,TB2 Tone Buzzer

21~24 ROW0~RO

W3 COMmon driving output

1~8、25~48 DOT0~DOT

31 SEGment driving output

BL55021



5 Absolute Maximum Rating Parameter Symbol Rating Unit

Supply Voltage VDD -0.3～5.5 V

Input voltage VIL Vss-0.3～ VDD +0.3 V

Operating temperature Topr -40～ +85 oC

Storage temperature Tstg -50～ +125 oC

6 DC Characteristic Ta=25oC

Test Condition Symbol Parameter Vdd condition

Min Typ Max Unit

Vdd Operating voltage ---- ---- 2.4 ---- 5.2 V 3V ---- 150 300

Idd1 5V Unload/LCD on

On chip RC oscillator ---- 300 600 3V ---- 60 120

Idd2 5V Unload/LCD on Crystal oscillator ---- 120 240

3V ---- 100 200 Idd3

Operating current

5V Unload/LCD on External clock ---- 200 400

uA

3V ---- 0.1 5 Istb

Standby current 5V

Unload Standby mode ---- 0.3 10

uA

3V 0 --- 0.6 Vil

Input Low Voltage 5V

DI,CPW,CS,READ 0 --- 1.0

V

3V 2.4 --- 3.0 Vih

Input High Voltage 5V

DI,CPW,CS,READ 4.0 --- 5.0

V

3V Vol=0.3V 0.5 1.2 --- Iol1 DI,TB,TIS 5V Vol=0.5V 1.3 2.5 ---

mA

3V Vol=2.7V -0.4 -0.8 --- Ioh1 DI,TB,TIS 5V Vol=4.5V -0.9 -1.8 ---

mA

3V Vol=0.3V 80 150 --- Iol2 ROW 5V Vol=0.5V 159 250 ---

uA

3V Vol=2.7V -80 -120 --- Ioh2 ROW 5V Vol=4.5V -120 -200 ---

uA

3V Vol=0.3V 60 120 --- Iol3 DOT 5V Vol=0.5V 120 200 ---

uA

3V Vol=0.3V -40 -70 --- Ioh3 DOT 5V Vol=0.5V -70 -100 ---

uA

3V 40 80 150 kΩ Rph

Pull high resister 5V

DI,CPW,CS,TREAD 30 60 100 kΩ

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7 AC Characteristic Ta=25oC Test Condition Symbol Parameter

Vdd

condition Min Typ Max Unit

3V ---- 256 ---- Fsys1 5V

On chip RC oscillator ---- 256 ----

3V ---- 32.768 ---- Fsys2 5V

Crystal oscillator ---- 32.768 ----

3V ---- 256 ---- Fsys3

System clock

5V

External Clock ---- 256 ----

kHz

--- On chip RC oscillator

---- fSYS1 / 1024

----

--- Crystal oscillator

---- fSYS2 / 128

----

Flcd1

LCD scan frequency

--- External Clock

---- fSYS3 / 1024

----

Hz Hz

Tcom

ROW period

--- N:Number of COM ---- N/Flcd ---- S

3V ---- ---- 300 Fclk1 CPW clock 5V

50% duty ---- ---- 500

kHz

3V ---- ---- 75 Fclk2 TREAD clock 5V

50% duty ---- ---- 150

kHz

Ftb Tone - On chip RC oscillator ---- 2.0/4.0 --- kHz Tcs Reset pulde wirth CS ---- 250 ---- ns

Write 3.34 ---- ---- 3V Read 6.67 ---- ---- Write 1.67 ---- ----

Tclk CPW Pulse width

5V Read 3.34 ---- ----

us

Tr,Tf Rise/Fall width ---- 120 ---- ns Tsu DI-clock setup width ---- 120 ---- ns Th DI-clock hold width ---- 120 ---- ns Tsu1 CS-clock setup width ---- 100 ---- ns Th1 CS-clock hold width ---- 100 ---- ns

BL55021



8 Functional Description Display Memory _ RAM

The static display memory (RAM) is organized into 32 X 4 bits and stores the displayed

data. The contents of the RAM are directly mapped to the contents of the LCD driver. Data in

the RAM can be accessed by the WRITE commands. The following is a mapping from the

RAM to the LCD pattern:

System Oscillator

The BL55021 system clock is used to generate the time base/Watchdog Timer (WDT)

clock frequency, LCD driving clock, and tone frequency. The source of the clock may be from

an on-chip RC oscillator (256kHz), a crystal oscillator (32.768kHz), or an external 256kHz

clock by the S/W setting. The configuration of the system oscillator is as shown. After the

SYS DIS command is executed, the system clock will stop and the LCD bias generator will

turn off. That command is, however, available only for the on-chip RC oscillator or for the

crystal oscillator. Once the system clock stops, the LCD display will become blank, and the

time base/WDT lose its function as well. The LCD OFF command is used to turn the LCD

bias generator off. After the LCD bias generator switches off by issuing the LCD OFF

command, using the SYS DIS command reduces power consumption, serving as a system

power down command. But if the external clock source is chosen as the system clock, using

the SYS DIS command can neither turn the oscillator off nor carry out the power down mode.

The crystal oscillator option can be applied to connect an external frequency source of 32kHz

to the OSCI pin. In this case, the system fails to enter the power down mode, similar to the

case in the external 256kHz clock source operation. At the initial system power on, the

BL55021 is at the SYS DIS state.

Command Format The BL55021 can be configured by the S/W setting. There are two mode commands to

configure the BL55021 resources and to transfer the LCD display data. The configuration

mode of the BL55021 is called command mode, and its command mode ID is 1 0 0. The

command mode consists of a system configuration command, a system frequency selection

command, a LCD configuration command, a tone frequency selection command, a

timer/WDT setting command, and an operating command. The data mode, on the other hand,

includes READ, WRITE, and READ-MODIFY-WRITE operations. The following are the

data mode IDs and the command mode ID:

BL55021



The mode command should be issued before the data or command is transferred. If successive

commands have been issued, the command mode ID, namely 1 0 0, can be omitted. While the

system is operating in the non-successive command or the non-successive address data mode,

the CS pin should be set to “1” and the previous operation mode will be reset also. Once the

CS pin returns to “0” a new operation mode ID should be issued first.

9 Timing Diagrams Write mode

Write succesive

Write command

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10 Typical Application Circuit

Note: Adjust R to fit user. The voltage VLCD must be lower than VDD.

BL55021



11 Command Summary

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12 Package Infoemation SSOP48: plastic shrink small outline package; 48 leads; body with 7.5 mm

bl55021.pdf

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