LCD Driver for 140 Display Units BL55070 1 General Description 2

Shanghai Belling Corp., Ltd
zip: 200233 Tel: 86-021-64850700 Fax: 86-021-64855865
BL55070
LCD Driver for 140 Display Units BL55070
1 General Description
The BL55070 is a general LCD driver IC for 140 units LCD panel. It features a wide
operating supply voltage range, incorporates simple communication interface with
microcomputer and is suitable for multiple application.
2 Features
Advanced low power CMOS Technology
Selection of 1/2 or 1/3 bias, selection of 1/2 or 1/3 or 1/4 duty.
Operation voltage: 2.5~5.5V
Serial data interface
140(35x4) Display Units
Low power dissipation design: Power saving mode: Idd=14uA at 5V and Idd=9uA at
3.3V; Sleeping mode: Idd<2uA
On-chip RC oscillator
VLCD for adjusting LCD operating voltage
Excellent EMC immunity
Compatible with general microcomputer
LQFP44 package
3 Pin Assignment
Fig 1
1
Shanghai Belling Corp., Ltd
zip: 200233 Tel: 86-021-64850700 Fax: 86-021-64855865
BL55070
4
Pin Description
Pin No.
Pin name
Function
9
10
11
12
13
14-17
18-44、
、1-8
SDA
SCI
Vdd
Vss
Vlcd
Com0、Com2、Com1、Com3
S0——S34
Serial data input/output
Serial clock input
Supply voltage
ground
LCD supply voltage
Common terminal driving output
Segment terminal driving output
Tab.1
5
Function Description
1.function circuit
The BL550070 has all function circuits that can directly drive any static or multiplexed
LCD containing up to four commons and up to 35 segments. The function circuits
include:Power-on reset, LCD bias generator, LCD voltage selector, Oscillator, display RAM,
Timing, Display latch, Shift register, Common/segment outputs, input/output bank selector,
Blinker, Data pointer, etc.
2.display function decription
The display RAM is a static 35x 4-bit RAM which stores LCD data. A logic 1 in the
RAM bit-map indicates the on state of the corresponding LCD segment; similarly, a logic 0
indicates the off state. There is a one-to-one correspondence between the RAM addresses and
the segment outputs, and between the individual bits of a RAM word and the common outputs.
(see Fig.2).
Display RAM address and SEGMENT(
(S0~S34)
)output
0
COM
(Com0~
Com3)
输出
1
2
3
。
。
。
。
31
32
33
34
0
1
2
3
Fig2
When display data is transmitted to the BL55070, the display bytes received are stored
in the display RAM in accordance with the selected LCD drive mode. To illustrate the filling
order, an example of a 7-segment numeric display showing all drive modes is given in Fig.3;
the RAM filling organization depicted applies equally to other LCD types.
2
BL55070
Shanghai Belling Corp., Ltd
zip: 200233 Tel: 86-021-64850700 Fax: 86-021-64855865
Fig 3
I2C-bus protocol
I2C-bus slave addresses (0111000) are reserved for the BL55070
The I2C-bus protocol is shown in Fig.4. The sequence is initiated with a START
condition (S) from the I2C-bus master which is followed by the BL55070 slave addresses
available. After acknowledgement, one or more command bytes (m) follow which define the
status of the addressed BL55070. The last command byte is tagged with a cleared most
significant bit, the continuation bit C. The command bytes are also acknowledged by the
addressed BL55070 on the bus. After the last command byte, a series of display data bytes(n)
may follow. These display bytes are stored in the display RAM at the address specified by the
data pointer. Data pointer are automatically updated and the data is directed to the intended
BL55070 device. After the last display byte, the I2C-bus master issues a STOP condition (P).
3.
3
BL55070
Shanghai Belling Corp., Ltd
zip: 200233 Tel: 86-021-64850700 Fax: 86-021-64855865
Fig 4
4. command decoder
The command decoder identifies command bytes that arrive on the I2C-bus. All
available commands carry a continuation bit C in their most significant bit position. The four
commands available to the BL55070 are defined in Fig 5.
4
Shanghai Belling Corp., Ltd
zip: 200233 Tel: 86-021-64850700 Fax: 86-021-64855865
BL55070
Fig 5
6
Absolute Maximum Rating
Parameter
Symbol
Rating
Unit
Supply voltage
LCD operating voltage
Input voltage
Output voltage
Vdd,Vss,Vlcd current
Maximum power consumption
Operating temperature
Storage temperature
Vdd
Vlcd
Vi
Vo
Idd,Iss,Ilcd
Ptot
Topr
Tstg
-0.5~+6.0
0~ Vdd
Vss-0.5~Vdd+0.5
Vlcd-0.5~Vdd+0.5
-50~+50
400
-40~ +75
-65~ +150
V
V
V
V
mA
mW
o
C
o
C
7
DC Characteristic
Symbol Parameter
Vdd
Idd1
IC Operating
voltage
LCD operating
voltage
Supply current
Idd2
Supply current
Idd3
Supply current
Idd4
Supply current
Vlcd
ISL
Sleep current
Test Condition
Min
Vdd=5V,VLCD=0V,Normal
mode,internal oscillator
Vdd=5V,VLCD=0V,power saving
mode,internal oscillator
Vdd=3.3V,VLCD=0V,Normal
mode,internal oscillator
Vdd=3.3V,VLCD=0V,power saving
mode,internal oscillator
Vdd=5V,VLCD=0V
Typ
Max
Unit
2.5
-
5.5
V
0
-
Vdd-2
V
-
25
50
uA
-
14
30
uA
-
16
30
uA
-
9
15
uA
-
1.5
2
uA
ViL
Low voltage input
SDA,SCL
Vss
-
0.3Vdd
V
ViH
High voltage
input
SDA,SCL
0.7Vdd
-
6.0
V
5
BL55070
8
Shanghai Belling Corp., Ltd
zip: 200233 Tel: 86-021-64850700 Fax: 86-021-64855865
Ta=25oC
AC Characteristic
Symbol
Parameter
Test Condition
Min
Typ
Max
Unit
Fclk
Fclklp
Tclkh
Tclkl
TBUF
Thd;STA
Tlow
Thigh
Oscillator frequency
Oscillator frequency
CLK HIGH time
CLK LOW time
Bus free time
START hold time
SCL LOW time
SCL HIGH time
Vdd=5V,normal mode
Vdd=3.3V, power saving
125
21
1
1
4.7
4
4.7
4
180
31
-
300
48
-
KHz
KHz
us
us
us
us
us
us
Tsu;STA
Thd;DAT
Tsu;DAT
Tr
Tf
Tsu;STO
START set-up time
Data hold time
Data set-up time
Rise time
fall time
STOP set-up time
4.7
0
250
4.7
-
1
300
-
us
us
ns
us
ns
us
mode
Fig 6
9
Typical Application Circuit
Note:1/ when I2C are idle mode,SDA and SCL must be connect to high level(by pull up
resistor),otherwise the device maybe can not go into power saving mode.
2/
In power-saving mode, SCL frequency must be less than 21KHz.
3/
Work at 1/3 bias, Vdd – Vlcd must be more than 2.9V。
2.9V。
Fig 7
6
BL55070
10
Shanghai Belling Corp., Ltd
zip: 200233 Tel: 86-021-64850700 Fax: 86-021-64855865
Package Outline
LQFP44
Fig 8
7