PCF1178CUSLASH10 datasheet(7/20 Pages) PHILIPS

7 / 20 page

1997 Apr 16

Philips Semiconductors

Product speciﬁcation

4-digit duplex LCD car clock

PCF1178C

The number (n) is stored in a non-volatile memory which is achieved by the following steps (see Fig.6):

1. Set SEL to VSS and a level of VDD − 5 V to VPP

2. The quartz-frequency deviation

∆f/f is measured and (n) is calculated (see Table 1)

3. A first pulse tE is applied to the DATA input clears the EEPROM to give the highest backplane frequency

4. The calculated pulses (n) are entered in (tH, tL). If the maximum backplane period is reached and an additional pulse

is applied the period will return to the lowest value.

5. The backplane period is controlled and when correct fixed by applying the store pulse tW

6. Release SEL and VPP.

Table 1

Time calibration (

∆t = 7.63 µs; SEL at VSS)

OSCILLATOR-FREQUENCY DEVIATION

∆f/f

(

× 10−6)

NUMBER OF PULSES

(n)

BACKPLANE PERIOD

(ms)

15.625

+3.8

15.633

+7.6

15.641

+11.4

15.648

+117.8

15.861

PCF1178CU/10 Datasheet(PDF) 7 Page - NXP Semiconductors