INTEGRATED CIRCUITS
DATA SHEET
PCF8576
Universal LCD driver for low multiplex rates
Product specification |
1998 Feb 06 |
Supersedes data of 1997 Nov 18
File under Integrated Circuits, IC12
Philips Semiconductors |
Product specification |
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Universal LCD driver for low multiplex
PCF8576
rates
CONTENTS
1FEATURES
2GENERAL DESCRIPTION
3ORDERING INFORMATION
4BLOCK DIAGRAM
5PINNING
6FUNCTIONAL DESCRIPTION
6.1Power-on reset
6.2LCD bias generator
6.3LCD voltage selector
6.4LCD drive mode waveforms
6.4.1Static drive mode
6.4.21 : 2 multiplex drive mode
6.4.31 : 3 multiplex drive mode
6.4.41 : 4 multiplex drive mode
6.5Oscillator
6.5.1Internal clock
6.5.2External clock
6.6Timing
6.7Display latch
6.8Shift register
6.9Segment outputs
6.10Backplane outputs
6.11Display RAM
6.12Data pointer
6.13Subaddress counter
6.14Output bank selector
6.15Input bank selector
6.16Blinker
7 |
CHARACTERISTICS OF THE I2C-BUS |
7.1Bit transfer
7.2START and STOP conditions
7.3System configuration
7.4Acknowledge
7.5PCF8576 I2C-bus controller
7.6Input filters
7.7I2C-bus protocol
7.8Command decoder
7.9Display controller
7.10Cascaded operation
8LIMITING VALUES
9HANDLING
10DC CHARACTERISTICS
11AC CHARACTERISTICS
11.1Typical supply current characteristics
11.2Typical characteristics of LCD outputs
12 APPLICATION INFORMATION
12.1 Chip-on-glass cascadability in single plane
13BONDING PAD LOCATIONS
14PACKAGE OUTLINES
15SOLDERING
15.1Introduction
15.2Reflow soldering
15.3Wave soldering
15.4Repairing soldered joints
16DEFINITIONS
17LIFE SUPPORT APPLICATIONS
18PURCHASE OF PHILIPS I2C COMPONENTS
1998 Feb 06 |
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Philips Semiconductors |
Product specification |
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Universal LCD driver for low multiplex
PCF8576
rates
1 FEATURES
·Single-chip LCD controller/driver
·Selectable backplane drive configuration: static or 2/3/4 backplane multiplexing
·Selectable display bias configuration: static, 1¤2 or 1¤3
·Internal LCD bias generation with voltage-follower buffers
·40 segment drives: up to twenty 8-segment numeric characters; up to ten 15-segment alphanumeric characters; or any graphics of up to 160 elements
·40 ´ 4-bit RAM for display data storage
·Auto-incremented display data loading across device subaddress boundaries
·Display memory bank switching in static and duplex drive modes
·Versatile blinking modes
·LCD and logic supplies may be separated
·Wide power supply range: from 2 V for low-threshold LCDs and up to 9 V for guest-host LCDs and high-threshold (automobile) twisted nematic LCDs
·Low power consumption
·Power-saving mode for extremely low power consumption in battery-operated and telephone applications
·I2C-bus interface
·TTL/CMOS compatible
3 ORDERING INFORMATION
·Compatible with any 4-bit, 8-bit or 16-bit microprocessors/microcontrollers
·May be cascaded for large LCD applications (up to 2560 segments possible)
·Cascadable with 24-segment LCD driver PCF8566
·Optimized pinning for plane wiring in both single and multiple PCF8576 applications
·Space-saving 56-lead plastic very small outline package (VSO56)
·Very low external component count (at most one resistor, even in multiple device applications)
·Compatible with chip-on-glass technology
·Manufactured in silicon gate CMOS process.
2 GENERAL DESCRIPTION
The PCF8576 is a peripheral device which interfaces to almost any Liquid Crystal Display (LCD) with low multiplex rates. It generates the drive signals for any static or multiplexed LCD containing up to four backplanes and up to 40 segments and can easily be cascaded for larger LCD applications. The PCF8576 is compatible with most microprocessors/microcontrollers and communicates via a two-line bidirectional I2C-bus. Communication overheads are minimized by a display RAM with auto-incremented addressing, by hardware subaddressing and by display memory switching (static and duplex drive modes).
TYPE NUMBER |
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PACKAGE |
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NAME |
DESCRIPTION |
VERSION |
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PCF8576T |
VSO56 |
plastic very small outline package; 56 leads |
SOT190-1 |
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PCF8576U |
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chip in tray |
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PCF8576U/2 |
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chip with bumps in tray |
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PCF8576U/5 |
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unsawn wafer |
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PCF8576U/7 |
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chip with bumps on tape |
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PCF8576U/10 |
FFC |
chip on film frame carrier (FFC) |
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PCF8576U/12 |
FFC |
chip with bumps on film frame carrier (FFC) |
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1998 Feb 06 |
3 |
_
06 Feb 1998
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4 |
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BLOCK |
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BP0 BP2 BP1 BP3 |
S0 to S39 |
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DIAGRAM |
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40 |
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13 |
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17 to 56 |
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5 |
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BACKPLANE |
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VDD |
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DISPLAY SEGMENT OUTPUTS |
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OUTPUTS |
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R |
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LCD |
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DISPLAY LATCH |
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R |
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VOLTAGE |
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SELECTOR |
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R |
LCD BIAS |
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SHIFT REGISTER |
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12 |
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GENERATOR |
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VLCD |
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4 |
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PCF8576 |
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CLK |
TIMING |
BLINKER |
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INPUT |
DISPLAY |
OUTPUT |
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3 |
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BANK |
RAM |
BANK |
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SYNC |
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SELECTOR |
40 x 4 BITS |
SELECTOR |
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DISPLAY |
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CONTROLLER |
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OSCILLATOR |
POWER- |
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OSC |
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DATA |
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ON |
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POINTER |
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RESET |
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11 |
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COMMAND |
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VSS |
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DECODER |
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2 |
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SUB- |
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SCL |
INPUT |
I2C - BUS |
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ADDRESS |
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1 |
FILTERS |
CONTROLLER |
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COUNTER |
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SDA |
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SA0 |
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A0 |
A1 |
A2 |
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MBK276 |
pagewidthfull Fig.1 Block diagram (for VSO56handbook, package; SOT190-1).
multiplex low for driver LCD Universal rates
PCF8576
Semiconductors Philips
specification Product
Philips Semiconductors |
Product specification |
|
|
Universal LCD driver for low multiplex
PCF8576
rates
5 PINNING
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SYMBOL |
PIN |
DESCRIPTION |
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SDA |
1 |
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I2C-bus serial data input/output |
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SCL |
2 |
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I2C-bus serial clock input |
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3 |
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cascade synchronization input/output |
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SYNC |
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CLK |
4 |
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external clock input/output |
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VDD |
5 |
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supply voltage |
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OSC |
6 |
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oscillator input |
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A0 to A2 |
7 to |
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I2C-bus subaddress inputs |
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SA0 |
10 |
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I2C-bus slave address input; bit 0 |
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VSS |
11 |
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logic ground |
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VLCD |
12 |
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LCD supply voltage |
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BP0, BP2, BP1 and BP3 |
13 to |
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LCD backplane outputs |
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S0 to S39 |
17 to |
56 |
LCD segment outputs |
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1998 Feb 06 |
5 |
Philips Semiconductors |
Product specification |
|
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Universal LCD driver for low multiplex
PCF8576
rates
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SDA |
1 |
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56 |
S39 |
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SCL |
2 |
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55 |
S38 |
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SYNC |
3 |
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54 |
S37 |
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CLK |
4 |
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53 |
S36 |
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VDD |
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5 |
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52 |
S35 |
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OSC |
6 |
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51 |
S34 |
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A0 |
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50 |
S33 |
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A1 |
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S32 |
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A2 |
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S31 |
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SA0 |
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S30 |
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VSS |
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11 |
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S29 |
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VLCD |
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12 |
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45 |
S28 |
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BP0 |
13 |
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S27 |
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BP2 |
14 |
PCF8576T |
43 |
S26 |
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BP1 |
15 |
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42 |
S25 |
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BP3 |
16 |
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S24 |
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S0 |
17 |
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40 |
S23 |
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S1 |
18 |
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S22 |
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S2 |
19 |
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38 |
S21 |
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S3 |
20 |
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37 |
S20 |
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S4 |
21 |
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36 |
S19 |
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S5 |
22 |
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S18 |
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S6 |
23 |
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S17 |
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S7 |
24 |
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S16 |
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S8 |
25 |
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32 |
S15 |
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S9 |
26 |
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31 |
S14 |
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S10 |
27 |
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30 |
S13 |
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S11 |
28 |
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S12 |
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MBK278 |
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Fig.2 Pin configuration; SOT190-1.
1998 Feb 06 |
6 |
Philips Semiconductors |
Product specification |
|
|
Universal LCD driver for low multiplex
PCF8576
rates
6 FUNCTIONAL DESCRIPTION
The PCF8576 is a versatile peripheral device designed to interface to any microprocessor/microcontroller to a wide variety of LCDs. It can directly drive any static or multiplexed LCD containing up to four backplanes and up to 40 segments. The display configurations possible with the PCF8576 depend on the number of active backplane outputs required; a selection of display configurations is given in Table 1.
All of the display configurations given in Table 1 can be implemented in the typical system shown in Fig.3.
The host microprocessor/microcontroller maintains the 2-line I2C-bus communication channel with the PCF8576. The internal oscillator is selected by connecting pin OSC to pin VSS. The appropriate biasing voltages for the multiplexed LCD waveforms are generated internally. The only other connections required to complete the
system are to the power supplies (VDD, VSS and VLCD) and the LCD panel chosen for the application.
Table 1 Selection of display configurations
NUMBER OF |
7-SEGMENTS NUMERIC |
14-SEGMENTS |
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ALPHANUMERIC |
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DOT MATRIX |
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BACKPLANES |
SEGMENTS |
DIGITS |
INDICATOR |
CHARACTERS |
INDICATOR |
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SYMBOLS |
SYMBOLS |
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4 |
160 |
20 |
20 |
10 |
20 |
160 dots (4 × 40) |
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3 |
120 |
15 |
15 |
8 |
8 |
120 dots (3 × 40) |
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2 |
80 |
10 |
10 |
5 |
10 |
80 dots (2 × 40) |
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40 |
5 |
5 |
2 |
12 |
40 dots (1 × 40) |
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VDD |
R |
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2CB |
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V |
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V |
LCD |
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DD |
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SDA |
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12 |
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HOST |
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1 |
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17 to 56 |
40 segment drives |
LCD PANEL |
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MICRO- |
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SCL |
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PROCESSOR/ |
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2 |
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PCF8576 |
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(up to 160 |
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MICRO- |
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OSC |
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elements) |
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CONTROLLER |
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6 |
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13 to 16 |
4 backplanes |
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ROSC |
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9 |
10 |
11 |
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A0 |
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A1 |
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A2 |
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SA0 |
V |
MBK277 |
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VSS |
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SS |
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Fig.3 Typical system configuration.
1998 Feb 06 |
7 |
Philips Semiconductors |
Product specification |
|
|
Universal LCD driver for low multiplex
PCF8576
rates
6.1Power-on reset
At power-on the PCF8576 resets to a starting condition as follows:
1.All backplane outputs are set to VDD.
2.All segment outputs are set to VDD.
3.The drive mode ‘1 : 4 multiplex with 1¤3bias’ is selected.
4.Blinking is switched off.
5.Input and output bank selectors are reset (as defined in Table 5).
6.The I2C-bus interface is initialized.
7.The data pointer and the subaddress counter are cleared.
Data transfers on the I2C-bus should be avoided for 1 ms following power-on to allow completion of the reset action.
6.2LCD bias generator
The full-scale LCD voltage (Vop) is obtained from
VDD - VLCD. The LCD voltage may be temperature compensated externally through the VLCD supply to pin 12.
Fractional LCD biasing voltages are obtained from an internal voltage divider of the three series resistors connected between VDD and VLCD. The centre resistor can be switched out of the circuit to provide a 1¤2bias voltage level for the 1 : 2 multiplex configuration.
6.3LCD voltage selector
The LCD voltage selector co-ordinates the multiplexing of the LCD in accordance with the selected LCD drive configuration. The operation of the voltage selector is controlled by MODE SET commands from the command decoder. The biasing configurations that apply to the preferred modes of operation, together with the biasing
characteristics as functions of Vop = VDD - VLCD and the resulting discrimination ratios (D), are given in Table 2.
A practical value for Vop is determined by equating Voff(rms) with a defined LCD threshold voltage (Vth), typically when
the LCD exhibits approximately 10% contrast. In the static drive mode a suitable choice is Vop > 3Vth approximately.
Multiplex drive ratios of 1 : 3 and 1 : 4 with 1¤2bias are possible but the discrimination and hence the contrast
ratios are smaller ( 3 = 1.732 for 1 : 3 multiplex or
21
---------- = 1.528 for 1 : 4 multiplex). 3
The advantage of these modes is a reduction of the LCD full-scale voltage Vop as follows:
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1 : 3 multiplex (1¤2bias): |
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Vop = |
6 ´ Voff á rmsñ = 2.449 Voff(rms) |
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1 : 4 multiplex (1¤2bias): |
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V |
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(4 ´ 3) |
= 2.309 V |
off(rms) |
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op |
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----------------------- |
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3 |
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These compare with Vop = 3 Voff(rms) when 1¤3bias is used.
Table 2 Preferred LCD drive modes: summary of characteristics
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NUMBER OF |
LCD BIAS |
Voff(rms) |
Von(rms) |
Von(rms) |
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LCD DRIVE MODE |
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-------------------- |
-------------------- |
D = -------------------- |
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BACKPLANES |
LEVELS |
CONFIGURATION |
Vop |
Vop |
Voff(rms) |
static |
1 |
2 |
static |
0 |
1 |
¥ |
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1 : 2 |
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3 |
1¤2 |
0.354 |
0.791 |
2.236 |
1 : 2 |
2 |
4 |
1¤3 |
0.333 |
0.745 |
2.236 |
1 : 3 |
3 |
4 |
1¤3 |
0.333 |
0.638 |
1.915 |
1 : 4 |
4 |
4 |
1¤3 |
0.333 |
0.577 |
1.732 |
1998 Feb 06 |
8 |
Philips Semiconductors |
Product specification |
|
|
Universal LCD driver for low multiplex
PCF8576
rates
6.4LCD drive mode waveforms
6.4.1STATIC DRIVE MODE
The static LCD drive mode is used when a single backplane is provided in the LCD. Backplane and segment drive waveforms for this mode are shown in Fig.4.
6.4.21 : 2 MULTIPLEX DRIVE MODE
6.4.31 : 3 MULTIPLEX DRIVE MODE
When three backplanes are provided in the LCD, the 1 : 3 multiplex drive mode applies, as shown in Fig.7.
6.4.41 : 4 MULTIPLEX DRIVE MODE
When four backplanes are provided in the LCD, the 1 : 4 multiplex drive mode applies, as shown in Fig.8.
When two backplanes are provided in the LCD, the 1 : 2 multiplex mode applies. The PCF8576 allows use of 1¤2bias or 1¤3bias in this mode as shown in Figs 5 and 6.
Vstate1(t) = VSn(t) –VBP0(t)
Von(rms) = Vop
Vstate2(t) = VSn + 1(t) –VBP0(t)
Voff(rms) = 0 V
V DD
BP0
VLCD
V DD
Sn
VLCD
VDD
S n 
1
VLCD
Tframe
LCD segments
state 1 |
state 2 |
(on) |
(off) |
(a) waveforms at driver
V op
state 1 |
0 |
Vop
V op
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0 |
Vop
(b) resultant waveforms |
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at LCD segment |
MBE539 |
Fig.4 Static drive mode waveforms (Vop = VDD - VLCD).
1998 Feb 06 |
9 |
Philips Semiconductors |
Product specification |
|
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Universal LCD driver for low multiplex
PCF8576
rates
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VDD |
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BP0 |
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VLCD |
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VDD |
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BP1 |
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VLCD |
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Sn |
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VLCD |
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VLCD |
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Vop /2 |
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state 1 |
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state 2 |
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Vop |
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(b) resultant waveforms |
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MBE540 |
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at LCD segment |
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Vstate1(t) = VSn(t) –VBP0(t)
Von(rms) = 0.791Vop
Vstate2(t) = VSn(t) –VBP1(t)
Voff(rms) = 0.354Vop
Fig.5 Waveforms for the 1 : 2 multiplex drive mode with 1¤2bias (Vop = VDD - VLCD).
1998 Feb 06 |
10 |
Philips Semiconductors |
Product specification |
|
|
Universal LCD driver for low multiplex
PCF8576
rates
BP0
BP1
Sn
S n 
1
state 1
state 2
VDD |
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Tframe |
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LCD segments |
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VDD |
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Vop /3 |
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VDD |
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VLCD |
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state 1 |
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VDD |
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state 2 |
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VDD |
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VDD |
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VLCD |
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VDD |
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VDD |
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VDD |
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VLCD |
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(a) waveforms at driver |
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Vop
2Vop /3
Vop /3
0
Vop /3
2Vop /3
Vop
Vop
2Vop /3
Vop /3
0
Vop /3
2Vop /3
Vop
(b) resultant waveforms |
MBE541 |
|
at LCD segment |
||
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Vstate1(t) = VSn(t) –VBP0(t)
Von(rms) = 0.745Vop
Vstate2(t) = VSn(t) –VBP1(t)
Voff(rms) = 0.333Vop
Fig.6 Waveforms for the 1 : 2 multiplex drive mode with 1¤3bias (Vop = VDD - VLCD).
1998 Feb 06 |
11 |
Philips Semiconductors |
Product specification |
|
|
Universal LCD driver for low multiplex
PCF8576
rates
BP0
BP1
BP2/S23
S n
Sn 
1
Sn 
2
state 1
state 2
Vstate1(t) = VSn(t) –VBP0(t)
Von(rms) = 0.638Vop
Vstate2(t) = VSn(t) –VBP1(t)
Voff(rms) = 0.333Vop
VDD |
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VLCD |
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VDD |
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VDD |
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VLCD |
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(a) waveforms at driver |
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Vop |
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2V op /3 |
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Vop /3 |
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Vop /3 |
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2V op /3 |
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(b) resultant waveforms |
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at LCD segment |
LCD segments
state 1 |
state 2 |
MBE542
Fig.7 Waveforms for the 1 : 3 multiplex drive mode (Vop = VDD − VLCD).
1998 Feb 06 |
12 |
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