Philips pcf1175c DATASHEETS

INTEGRATED CIRCUITS

DATA SH EET

PCF1175C

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 PCF1175C

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 PCF1175C 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

TYPE

NUMBER

NAME DESCRIPTION VERSION

PCF1175CT SO28 plastic small outline package; 28 leads; body width 7.5 mm
PCF1175CU − uncased chip in tray

(2)

PCF1175CU/10 − chip-on-film frame carrier (FFC)

PACKAGE

(1)

(2)

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.

SOT136-1

−

−

1997 Apr 16 2

Philips Semiconductors Product specification

4-digit duplex LCD car clock PCF1175C

PINNING

SYMBOL PIN DESCRIPTION

S1 1 hour adjustment input
DATA 2 EEPROM data input
OSC IN 3 oscillator input
OSC OUT 4 oscillator output
V

SS

MODE 6 12/24-hour mode select input
V

PP

TS 8 test speed-up mode input
ENABLE 9 enable input (for S1 and S2)
V

DD

FLASH 11 colon option input
SEL 12 EEPROM select input
S2 13 minute adjustment input
B4/C4 14 segment driver
G4/D4 15 segment driver
F4/E4 16 segment driver
B3/C3 17 segment driver
G3/AD3 18 segment driver
F3/E3 19 segment driver
A4/COL 20 segment driver
B2/C2 21 segment driver
G2/D2 22 segment driver
F2/E2 23 segment driver
B1/C1 24 segment driver
A2/ADEG1 25 segment driver
AM/PM 26 segment driver
BP2 27 backplane 2
BP1 28 backplane 1

5 negative supply voltage

7 programming voltage input

10 positive supply voltage

1

S1

DATA

OSC IN

OSC OUT

V

SS

MODE

V

PP
TS

ENABLE

V

DD

FLASH

SEL

S2

B4/C4

2
3
4
5
6
7

PCF1175CT

8

9
10
11
12
13

MSB222

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

BP1
BP2
AM/PM
A2/ADEG1
B1/C1
F2/E2
G2/D2
B2/C2
A4/COL
F3/E3
G3/AD3
B3/C3
F4/E4
G4/D4

Fig.1 Pin configuration, PCF1175CT, (SO28).

1997 Apr 16 3

Philips Semiconductors Product specification

4-digit duplex LCD car clock PCF1175C

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

P1 (P3)

P2 (P4)

ON(RMS)
OFF(RMS)

= 0.79 V

= 0.35 VDD.

F3

E3

A3

G3

D3

DD

B3

C3

F4

E4

A4

G4

D4

MSA992

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 PCF1175C

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= 5 to 6 V at −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 PCF1175C

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: 12-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 1 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 one advance 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 are inhibited every
second of operation.

1997 Apr 16 6