Philips PCF1178CT, PCF1178CU-10 Datasheet

INTEGRATED CIRCUITS

DATA SH EET

PCF1178C

4-digit duplex LCD car clock

Product specification
Supersedes data of September 1993
File under Integrated Circuits, IC16

1997 Apr 16

Philips Semiconductors Product specification

4-digit duplex LCD car clock PCF1178C

FEATURES

• Internal voltage regulator is electrically programmable
for various LCD voltages

• Time calibration is electrically programmable
(no trimming capacitor required)

• LCD voltage adjusts with temperature for good contrast

• 4.19 MHz oscillator

• 12-hour or 24-hour mode

• Operating ambient temperature: −40 to +85 °C

GENERAL DESCRIPTION

The PCF1178C is a single chip, 4.19 MHz CMOS car clock
circuit providing hours, minutes and seconds functions.
It is designed to drive a 4-digit duplex liquid crystal display
(LCD).

Two external single-pole, single-throw switches will
accomplish all time setting functions. Time calibration and
voltage regulator are electrically programmable via an
on-chip EEPROM. The circuit is battery-operated via an
internal voltage regulator and an external resistor.

• 28-lead plastic SMD (SO28)

• 1 Hz set mode.

ORDERING INFORMATION

PACKAGE

TYPE NUMBER

NAME DESCRIPTION VERSION

PCF1178CT SO28 plastic small outline package; 28 leads; body width 7.5 mm
PCF1178CU − uncased chip in tray
PCF1178CU/10 − chip-on-film frame carrier (FFC)
PCF1178CU/5 − unsawn wafer

(2)

(2)

(2)

(1)

SOT136-1

−

−

−

Notes

1. See Fig.1 and Chapter “Package outline” for pin layout and package details.

2. See Chapter “Chip dimensions and bonding pad locations” for pad layout and package details.

1997 Apr 16 2

Philips Semiconductors Product specification

4-digit duplex LCD car clock PCF1178C

PINNING

SYMBOL PIN DESCRIPTION

BP1 1 backplane 1
BP2 2 backplane 2
AM/PM 3 segment driver
A2/ADEG1 4 segment driver
B1/C1 5 segment driver
F2/E2 6 segment driver
G2/D2 7 segment driver
B2/C2 8 segment driver
A4/COL 9 segment driver
F3/E3 10 segment driver
G3/AD3 11 segment driver
B3/C3 12 segment driver
F4/E4 13 segment driver
G4/D4 14 segment driver
B4/C4 15 segment driver
S2 16 minute adjustment input
SEL 17 EEPROM select input
FLASH 18 colon option input
V

DD

19 positive supply voltage
ENABLE 20 enable input (for S1 and S2)
TS 21 test speed-up mode input
V

PP

22 programming voltage input
MODE 23 12/24-hour mode select input
V

SS

24 negative supply voltage
OSC OUT 25 oscillator output
OSC IN 26 oscillator input
DATA 27 EEPROM data input
S1 28 hour adjustment input

AM/PM

A2/ADEG1

A4/COL

G3/AD3

Fig.1 Pin configuration, PCF1178CT, (SO28).

BP1
BP2

B1/C1

F2/E2

G2/D2

B2/C2

F3/E3

B3/C3

F4/E4

G4/D4

1
2
3
4
5
6
7

PCF1178CT

8

9
10
11
12
13

MSB229

28
27
26
25
24
23
22
21
20
19
18
17
16
1514

S1
DATA
OSC IN
OSC OUT

V

SS

MODE
V

PP

TS
ENABLE
V

DD

FLASH
SEL
S2
B4/C4

1997 Apr 16 3

Philips Semiconductors Product specification

4-digit duplex LCD car clock PCF1178C

FUNCTIONAL DESCRIPTION AND TESTING
Outputs

The circuit outputs 1 : 2 multiplexed data (duplex) to the
LCD. Generation of BP1 and BP2 (three-level backplane
signals) and the output signals are shown in Fig.4.

F2

E2

A2

G2

AM

E1

A1

G1

B1

C1

PM

D1

Fig.2 Segment designation of LCD.

D2

The average voltages across the segments are:

B2

C2

1. V

2. V

ON(RMS)
OFF(RMS)

COL

= 0.79 V

= 0.35 VDD.

F3

E3

A3

G3

D3

DD

B3

C3

F4

E4

A4

G4

D4

MLB251

B4

C4

TIME

TIME

PM

(a)

a. 12-hour mode.

(b)

b. 24-hour mode.

MSA994

MSA993

BP1

BP2

SEGMENT1SEGMENT

ON ON

OFF ON

ON OFF

OFF OFF

2

MSB226

V

DD

VDD/2

V

DD

VDD/2

V

DD

V

DD

V

DD

V

DD

0

0

0

0

0

0

15.625 ms

Fig.3 Typical displays.

1997 Apr 16 4

Fig.4 Backplane and output signals.

Philips Semiconductors Product specification

4-digit duplex LCD car clock PCF1178C

LCD voltage (see Fig.5)
The adjustable voltage regulator controls the supply

voltage (see Section “LCD voltage programming”) in
relation to temperature for good contrast, for example
when VDD= 4.5 V at +25 °C, then:

VDD= 3 to 4 V at +85 °C.
VDD=5to6Vat−40 °C.

−8

V

SS

(V)

−6

−4

−2

0

40 0 40 120

(1) Programmed to 4.0 V at 25 °C (value within the specified operating range).
(2) Programmed to 4.5 V at 25 °C (value within the specified operating range).
(3) Programmed to 5.0 V at 25 °C (value within the specified operating range).

(3)

(2)
(1)

Fig.5 Regulated voltage as a function of temperature (typical).

80

MSA995

o

T ( C)

1997 Apr 16 5

Philips Semiconductors Product specification

4-digit duplex LCD car clock PCF1178C

12/24-hour mode

Operation in 12-hour or 24-hour mode is selected by
connecting MODE to VDD or VSS respectively. If MODE is
left open-circuit and a reset occurs, the mode will change
from 12-hour to 24-hour mode or vice versa.

Power-on

After connecting the supply, the start-up mode is:
MODE connected to V

: 12-hour mode, 1:00 AM.

DD

MODE connected to VSS: 24-hour mode, 0:00.
MODE left open-circuit: 24-hour mode, 0:00 or 1:00.

Colon

If FLASH is connected to V

the colon pulses at 0.5 Hz.

DD

If FLASH is connected to VSS the colon is static.

Time setting

Switch inputs S1 and S2 have a pull-up resistor to facilitate
the use of single-pole, single-throw contacts. A debounce
circuit is incorporated to protect against contact bounce
and parasitic voltages.

Set enable

Inputs S1 and S2 are enabled by connecting ENABLE to

or disabled by connecting to VSS.

V

DD

Set hours

When S1 is connected to V

the hours displayed

SS

advances by one and after one second continues with one
advance per second until S1 is released (auto-increment).

Set minutes

When S2 is connected to V

the time displayed in

SS

minutes advances by one and after one second continues
with two advances per second until S2 is released
(auto-increment). In addition to minute correction, the
seconds counter is reset to zero.

Segment test/reset

When S1 and S2 are connected to V

, all LCD segments

SS

are switched ON. Releasing switches S1 and S2 resets the
display. No reset occurs when DATA is connected to V

SS

(overlapping S1 and S2).

Test mode

When TS is connected to V

, the device is in normal

DD

operating mode. When connecting TS to VSS all counters
(seconds, minutes and hours) are stopped, allowing quick
testing of the display via S1 and S2 (debounce and
auto-increment times are 64 times faster). TS has a
pull-up resistor but for reasons of safety it should be
connected to VDD.

EEPROM

V

has a pull-up resistor but for reasons of safety it should

PP

be connected to VDD.

LCD voltage programming

To enable LCD voltage programming, SEL is set to
open-circuit and a level of V

− 5 V is applied to VPP (see

DD

Fig.6). The first pulse (tE) applied to the DATA input clears
the EEPROM to give the lowest voltage output. Further
pulses (tL) will increment the output voltage by steps of
typically 150 mV (T

=25°C). For programming,

amb

measure VDD− VSS and apply a store pulse (tW) when the
required value is reached. If the maximum number of steps
(n = 31) is reached and an additional pulse is applied the
voltage will return to the lowest value.

Time calibration

To compensate for the tolerance in the quartz crystal
frequency which has been positively offset (nominal

−6

deviation +60 × 10

) by capacitors at the oscillator input

and output, a number (n) of 262144 Hz pulses are
inhibited every second of operation.

1997 Apr 16 6