Philips pcf8576c DATASHEETS

INTEGRATED CIRCUITS

DATA SH EET

PCF8576C

Universal LCD driver for low multiplex rates

Product speciﬁcation Supersedes data of 1995 Jun 30 File under Integrated Circuits, IC12

1996 Dec 09

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

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 6 V for guest-host LCDs and high-threshold (automobile) twisted nematic LCDs.

A 9 V version is also available on request.

• Low power consumption

• Power-saving mode for extremely low power

consumption in battery-operated and telephone applications

2

C-bus interface

• I

• TTL/CMOS compatible

• 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 and multiple

PCF8576C applications

• Space-saving 56-lead plastic very small outline package (VSO56) or 64-lead low profile quad flat package (LQFP64)

• No external components

• Compatible with chip-on-glass technology

• Manufactured in silicon gate CMOS process.

GENERAL DESCRIPTION

The PCF8576C 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 PCF8576C is compatible with most microprocessors/microcontrollers and communicates via a two-line bidirectional I are minimized by a display RAM with auto-incremented addressing, by hardware subaddressing and by display memory switching (static and duplex drive modes).

2

C-bus. Communication overheads

ORDERING INFORMATION

TYPE NUMBER

PCF8576CT VSO56 plastic very small outline package; 56 leads SOT190-1 PCF8576CU − uncased chip in tray − PCF8576CU/10 FFC chip-on-ﬁlm frame carrier − PCF8576CH LQFP64 plastic low proﬁle quad ﬂat package; 64 leads; body 10 × 10 × 1.4 mm SOT314-2

1996 Dec 09 2

PACKAGE

NAME DESCRIPTION VERSION

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

BLOCK DIAGRAM

40

S0 to S39

16

BP3

15

BP1

14

BP2

13

BP0

17 to 56

DISPLAY LATCH

DISPLAY SEGMENT OUTPUTS

OUTPUTS

BACKPLANE

BANK

OUTPUT

RAM

DISPLAY

SHIFT REGISTER

BANK

INPUT

PCF8576C

SELECTOR

40 x 4 BITS

SELECTOR

DISPLAY

CONTROLLER

DATA

POINTER

SUB-

DECODER

COMMAND

9 8 7

ADDRESS

COUNTER

A2 A1 A0

MLD332

handbook, full pagewidth

LCD

VOLTAGE

SELECTOR

LCD BIAS

GENERATOR

5

DD

V

12

LCD

V

1996 Dec 09 3

4

CLK

TIMING BLINKER

3

SYNC

ON

RESET

POWER-

OSCILLATOR

6

OSC

Fig.1 Block diagram; VSO56.

10

2

I C - BUS

CONTROLLER

INPUT

FILTERS

SS

1

2

SCL

SDA

11

V

SA0

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

PINNING

SYMBOL

DESCRIPTION

SOT190 SOT314

2

SDA 1 10 I SCL 2 11 I

C-bus serial data input/output

2

C-bus serial clock input SYNC 3 12 cascade synchronization input/output CLK 4 13 external clock input V

DD

5 14 supply voltage

OSC 6 15 oscillator input

2

A0 to A2 7 to 9 16 to 18 I SA0 10 19 I V V

SS LCD

11 20 logic ground 12 21 LCD supply voltage

C-bus subaddress inputs

2

C-bus slave address input; bit 0

BP0, BP2, BP1, BP3 13 to 16 25 to 28 LCD backplane outputs S0 to S39 17 to 56 29 to 32, 34 to 47, 49 to 64, 2 to 7 LCD segment outputs n.c. − 1, 8, 9, 22 to 24, 33 and 48 not connected

1996 Dec 09 4

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

handbook, halfpage

SDA

SCL

SYNC

CLK

V

DD

OSC

A0 A1 A2

SA0

V

SS

V

LCD

BP0 BP2 BP1 BP3

S0 S1 S2 S3 S4 S5 S6 S7 S8

S9 S10 S11

1 2 3 4 5 6 7 8

9 10 11 12 13 14

PCF8576CT

15 16 17 18 19 20 21 22 23 24 25 26 27 28

MLD334

56

S39

55

S38

54

S37

53

S36

52

S35

51

S34

50

S33

49

S32

48

S31

47

S30

46

S29

45

S28

44

S27

43

S26

42

S25

41

S24

40

S23

39

S22

38

S21

37

S20

36

S19

35

S18

34

S17

33

S16

32

S15

31

S14

30

S13

29

S12

1996 Dec 09 5

Fig.2 Pin configuration; VSO56.

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

handbook, full pagewidth

n.c. S34 S35 S36 S37 S38 S39

n.c.

SDA

SCL

SYNC

CLK

V

DD

OSC

A0

S33

S32

S31

S30

S29

S28

S27

S26

S25

S24

S23

S22

S21

S20

S19

S18

64

63

62

61

60

59

58

57

56

55

54

53

52

51

50

49 1 2 3 4 5 6 7 8

48

n.c.

47

S17

46

S16

45

S15

44

S14

43

S13

42

S12

41

S11

PCF8576CH

9

10 11 12 13 14 15 16

40

S10

39

S9

38

S8

37

S7

36

S6

35

S5

34

S4

33

n.c.

17

18

19

20

21

22

23

A1

A2

SA0

SS

V

LCD

V

n.c.

Fig.3 Pin configuration; LQFP64.

1996 Dec 09 6

24

n.c.

25

BP0

26

BP2

27

BP1

28

BP3

29 S0

30 S1

31 S2

32

S3

MLD333

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

FUNCTIONAL DESCRIPTION

The PCF8576C 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 PCF8576C 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.4.

Table 1 Selection of display conﬁgurations

NUMBER OF 7-SEGMENTS NUMERIC

BACKPLANES SEGMENTS DIGITS

INDICATOR

SYMBOLS

4 160 20 20 10 20 160 dots (4 × 40) 3 120 15 15 8 8 120 dots (3 × 40) 2 80 10 10 5 10 80 dots (2 × 40) 1 40 5 5 2 12 40 dots (1 × 40)

The host microprocessor/microcontroller maintains the

2

2-line I

C-bus communication channel with the PCF8576C. The internal oscillator is selected by tying OSC (pin 6) to VSS (pin 11). 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 V

) and the LCD panel chosen for the

LCD

application.

14-SEGMENTS

ALPHANUMERIC

DOT MATRIX

CHARACTERS

INDICATOR

SYMBOLS

handbook, full pagewidth

V

DD

HOST

MICRO-

PROCESSOR/

MICRO-

CONTROLLER

V

SS

t

r

R

2C

B

SDA

SCL

OSC

V

DD

512

1 17 to 56

PCF8576CT

2 6

78

A0 A1 A2SSSA0 V

Fig.4 Typical system configuration.

1996 Dec 09 7

V

LCD

13 to 16

91011

40 segment drives

4 backplanes

LCD PANEL

(up to 160

elements)

MBE524

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

Power-on reset

At power-on the PCF8576C 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 with1⁄3bias’ 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.

2

Data transfers on the I

C-bus should be avoided for 1 ms

following power-on to allow completion of the reset action.

LCD bias generator

The full-scale LCD voltage (V VDD− V

. The LCD voltage may be temperature

LCD

compensated externally through the V

) is obtained from

op

supply to pin 12.

LCD

Fractional LCD biasing voltages are obtained from an internal voltage divider of the three series resistors connected between VDD and V

. The centre resistor can

LCD

be switched out of the circuit to provide a1⁄2bias voltage level for the 1 : 2 multiplex configuration.

LCD 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

− V

characteristics as functions of V

op=VDD

LCD

and the

resulting discrimination ratios (D), are given in Table 2. A practical value for Vop is determined by equating V

off(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 ( = 1.732 for 1 : 3 multiplex or

21

= 1.528 for 1 : 4 multiplex).

---------3

3

The advantage of these modes is a reduction of the LCD full-scale voltage V

• 1 : 3 multiplex ( Vop= = 2.449 V

6V

×

as follows:

op

1

⁄2bias):

off rms〈〉

off(rms)

• 1 : 4 multiplex (1⁄2bias):

These compare with Vop=3V

Table 2 Preferred LCD drive modes: summary of characteristics

LCD DRIVE MODE

NUMBER OF

BACKPLANES LEVELS

LCD BIAS

CONFIGURATION

static 1 2 static 0 1 ∞

1:2 2 3 1:2 2 4 1:3 3 4 1:4 4 4

V

43×()

= = 2.309 V

op

----------------------- 3

V

-------------------- -

1

⁄

2

1

⁄

3

1

⁄

3

1

⁄

3

off(rms)

when1⁄3bias is used.

off(rms)

V

op

V

on(rms)

-------------------- V

op

D

V

=

-------------------- V

on(rms) off(rms)

0.354 0.791 2.236

0.333 0.745 2.236

0.333 0.638 1.915

0.333 0.577 1.732

1996 Dec 09 8

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

LCD drive mode waveforms

S

TATIC 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.5.

T

frame

LCD segments

state 1

(on)

state 2

(off)

S

BP0

S

n 1

V

DD

V

LCD

V

DD

n

V

LCD

V

DD

V

LCD

(a) waveforms at driver

V

op

V

t() V

state1

=

V

on(rms)Vop

V

t() V

state2

V

off(rms)

state 1 0

V

op

V

op

state 2 0

V

op

(b) resultant waveforms

at LCD segment

t() V

BP0

t()–=

S

n

S

n1+

0V=

Fig.5 Static drive mode waveforms (Vop=VDD− V

MBE539

LCD

).

1996 Dec 09 9

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

1:2MULTIPLEX DRIVE MODE When two backplanes are provided in the LCD, the 1 : 2 multiplex mode applies. The PCF8576C allows use of1⁄2bias or

1

⁄3bias in this mode as shown in Figs 6 and 7.

T

frame

V

(V )/2V

BP0

V V

(V )/2V

BP1

V V

S

n

V V

S

n 1

V

V V /2

state 1 0

V /2 V

V V /2

state 2

V /2 V

DD DD LCD

LCD DD

LCD

DD

LCD DD

LCD

op

op op

op

0

op

(a) waveforms at driver

(b) resultant waveforms

at LCD segment

LCD segments

state 1 state 2

MBE540

V

t() V

0.791V

=

t() V

0.354V

=

S

t() V

n

t() V

n

BP0

op

BP1

op

state1

V

on(rms)

V

state2

V

off(rms)

Fig.6 Waveforms for the 1 : 2 multiplex drive mode with1⁄2bias (Vop=VDD− V

1996 Dec 09 10

t()–=

).

LCD

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

T

V

DD

V V /3

BP0

BP1

S

n

S

n 1

state 1 0

state 2 0

DD

V 2V /3

DD

V

LCD

V

DD

V V /3

DD

V 2V /3

DD

V

LCD

V

DD

V V /3

DD

V 2V /3

DD

V

LCD

V

DD

V V /3

DD

V 2V /3

DD

V

LCD

V

op

2V /3

op

V /3

op

V /3

op

2V /3

op

V

op

V

op

2V /3

op

V /3

op

V /3

op

2V /3

op

V

op

frame

(a) waveforms at driver

(b) resultant waveforms

at LCD segment

LCD segments

state 1 state 2

MBE541

V

t() V

0.745V

=

t() V

0.333V

=

S

t() V

n

t() V

n

BP0

op

BP1

op

state1

V

on(rms)

V

state2

V

off(rms)

Fig.7 Waveforms for the 1 : 2 multiplex drive mode with1⁄3bias (Vop=VDD− V

1996 Dec 09 11

t()–=

).

LCD

Philips Semiconductors Product speciﬁcation

Universal LCD driver for low multiplex rates PCF8576C

1:3MULTIPLEX DRIVE MODE When three backplanes are provided in the LCD, the 1 : 3 multiplex drive mode applies, as shown in Fig.8.

T

frame

(a) waveforms at driver

(b) resultant waveforms

at LCD segment

LCD segments

state 1 state 2

MBE542

V

state1

V

on(rms)

V

state2

V

off(rms)

t() V

0.638V

=

t() V

0.333V

=

S

t() V

n

t() V

n

BP0

BP1

BP2/S23

S

n 1

S

n 2

state 1 0

state 2 0

t()–=

BP0

op

t()–=

BP1

op

n

V

DD

V V /3

op

DD V 2V /3 V

V V V /3

V 2V /3 V

V V V /3

V 2V /3 V

V V V /3

V 2V /3 V

V V V /3

V 2V /3 V

V V V /3

V 2V /3 V

V

V V

V

DD

LCD

DD

LCD

DD

LCD

DD

LCD

DD

LCD

DD

LCD

op

2V /3

op

V /3

op

V /3

op

2V /3

op

2V /3

op

V /3

op

V /3

op

2V /3

op

1996 Dec 09 12

Fig.8 Waveforms for the 1 : 3 multiplex drive mode (Vop=VDD− V

LCD

).