Philips PCF1175CT-F2, PCF1175CU, PCF1175CU-10-F2, PCF1175CU-5-F2 Datasheet

DATA SH EET

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

1997 Apr 16

INTEGRATED CIRCUITS

PCF1175C

4-digit duplex LCD car clock

1997 Apr 16 2

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

• 28-lead plastic SMD (SO28)

• 1 Hz set mode.

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.

ORDERING INFORMATION

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.

TYPE

NUMBER

PACKAGE

NAME DESCRIPTION VERSION

PCF1175CT SO28 plastic small outline package; 28 leads; body width 7.5 mm

(1)

SOT136-1

PCF1175CU − uncased chip in tray

(2)

−

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

(2)

−

1997 Apr 16 3

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

5 negative supply voltage
MODE 6 12/24-hour mode select input
V

PP

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

DD

10 positive supply voltage
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

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

1
2
3
4
5
6
7
8

9
10
11
12
13

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

PCF1175CT

S1

DATA

OSC OUT

SS

MODE

PP
TS

ENABLE

DD

FLASH

SEL

S2

B4/C4

V

V

V

OSC IN

G4/D4

F4/E4

B3/C3

G3/AD3

F3/E3

A4/COL

B2/C2

G2/D2

F2/E2

B1/C1

A2/ADEG1

AM/PM

BP2

BP1

MSB222

1997 Apr 16 4

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.

The average voltages across the segments are:

1. V

ON(RMS)

= 0.79 V

DD

2. V

OFF(RMS)

= 0.35 VDD.

Fig.2 Segment designation of LCD.

MSA992

A2

G2

D2

F2

E2

B2

C2

P1 (P3)

P2 (P4)

A3

G3

D3

F3

E3

B3

C3

A4

G4

D4

F4

E4

B4

C4

AM

PM

A1

G1

D1

E1

B1

C1

Fig.3 Typical displays.

a. 12-hour mode.

b. 24-hour mode.

PM

TIME

MSA993

(a)

MSA994

TIME

(b)

Fig.4 Backplane and output signals.

MSB226

V

DD

VDD/2

0

BP1

V

DD

VDD/2

0

BP2

V

DD

0

SEGMENT1SEGMENT

2

ON ON

V

DD

0

OFF ON

V

DD

0

ON OFF

V

DD

0

OFF OFF

15.625 ms

1997 Apr 16 5

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.

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

(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).

40 0 40 120

−8

−6

−2

0

−4

MSA995

80

T ( C)

o

V

SS

(V)

(2)
(1)

(3)

1997 Apr 16 6

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

DD

: 12-hour mode, 1:00 AM.
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

DD

the colon pulses at 1 Hz.

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
V

DD

or disabled by connecting to VSS.

Set hours

When S1 is connected to V

SS

the hours displayed
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

SS

the time displayed in
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

SS

, all LCD segments
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

DD

, the device is in normal
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

PP

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

be connected to VDD.

LCD voltage programming

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

DD

− 5 V is applied to VPP (see
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

amb

=25°C). For programming,
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
deviation +60 × 10

−6

) by capacitors at the oscillator input
and output, a number (n) of 262144 Hz are inhibited every
second of operation.