zip: 200233 BL55028 Shanghai Belling Corp., Ltd Tel: 86-021-64850700 Fax: 86-021-64855865 LCD Driver for 76 Display Units BL55028 1 General Description The BL55028 is a general LCD driver IC for 76 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 76(19x4) Display Units Low power dissipation design: Power saving mode: Idd=14uA at 5V and Idd=9uA at 3.3V; On-chip RC oscillator VLCD for adjusting LCD operating voltage Excellent EMC immunity Compatible with general microcomputer SOP28 package 3 Pin Assignment S18 SDA 1 28 S17 2 27 S16 SCL 3 26 S15 VDD VSS 4 25 S14 5 24 S13 VLCD 6 23 S12 BP0 7 22 BP2 8 21 S10 S11 BP1 9 20 S9 BP3 10 19 S8 S0 11 18 S7 S1 12 17 S6 S2 13 16 S3 14 15 Fig 1 1 S5 S4 zip: 200233 BL55028 4 Shanghai Belling Corp., Ltd Tel: 86-021-64850700 Fax: 86-021-64855865 Pin Description Pin No. Pin name Function 2 3 4 5 6 7-10 11-28、 、1 SDA SCI Vdd Vss Vlcd Com0、Com2、Com1、Com3 S0——S18 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 BL550028 has all function circuits that can directly drive any static or multiplexed LCD containing up to four commons and up to 19 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 19x 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~S18） ）output 0 COM (Com0~ Com3) 输出 1 2 3 。 。 。 。 15 16 17 18 0 1 2 3 Fig2 When display data is transmitted to the BL55028, 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 BL55028 zip: 200233 Shanghai Belling Corp., Ltd Tel: 86-021-64850700 Fax: 86-021-64855865 Fig 3 I2C-bus protocol I2C-bus slave addresses (0111110) are reserved for the BL55028 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 BL55028 slave addresses available. After acknowledgement, one or more command bytes (m) follow which define the status of the addressed BL55028. 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 BL55028 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 BL55028 device. After the last display byte, the I2C-bus master issues a STOP condition (P). 3. 3 BL55028 zip: 200233 Shanghai Belling Corp., Ltd 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 BL55028 are defined in Fig 5. Fig 5 4 zip: 200233 BL55028 6 Shanghai Belling Corp., Ltd Tel: 86-021-64850700 Fax: 86-021-64855865 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 Test Condition Min Typ Max Unit Idd1 IC Operating voltage LCD operating voltage Supply current Idd2 Supply current Idd3 Supply current Idd4 Supply current ViL Low voltage input SDA,SCL Vss - 0.3Vdd V ViH High voltage input SDA,SCL 0.7Vdd - 6.0 V Vlcd 8 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 2.5 - 5.5 V 0 - Vdd-2 V - 25 50 uA - 14 30 uA - 16 30 uA - 9 15 uA Ta=25oC AC Characteristic Symbol Parameter Test Condition Min Typ Max Unit Fclk Vdd=5V,normal mode 125 180 300 KHz Vdd=3.3V, power saving mode 21 31 48 KHz 1 - 3 uA Tclk Oscillator frequency Oscillator frequency Half oscillator cycle Tsh1 CS start hold time 5 - us Tsh2 SCL start hold time 5 - us tlow High time 5 - us thig Low time 4 - us thd SCL hold time 250 Fclk 5 ns BL55028 zip: 200233 Shanghai Belling Corp., Ltd Tel: 86-021-64850700 Fax: 86-021-64855865 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。 。 Fig 7 6 BL55028 10 zip: 200233 Shanghai Belling Corp., Ltd Tel: 86-021-64850700 Fax: 86-021-64855865 Package Outline SOP28 Unit: inches (mm) Fig 8 7