Nxp Semiconductors PCA2125 用户手册
NXP Semiconductors
UM10301
User Manual PCF85x3, PCA8565 and PCF2123, PCA2125
Please be aware that important notices concerning this document and the product(s)
described herein, have been included in the section 'Legal information'.
described herein, have been included in the section 'Legal information'.
© NXP B.V. 2008. All rights reserved.
For more information, please visit: http://www.nxp.com
For sales office addresses, email to: salesaddresses@nxp.com
For sales office addresses, email to: salesaddresses@nxp.com
Date of release: 23 December 2008
Document identifier: UM10301_1
22. Contents
11.
Century and leap year, Daylight Saving Time. 25
11.1
Century tracking ...............................................25
11.2
Year and leap year tracking .............................25
11.3
Daylight Saving Time (DST).............................25
12.
Initialization and setting of alarm and timer....26
12.1
Initialization of the RTC and setting the time ....26
12.2
Alarm................................................................27
12.3
Setting the timer ...............................................29
13.
Backup power supply ....................................... 30
13.1
Lithium Primary cells ........................................30
13.2
NiCd and NiMH secondary batteries ................32
13.3
Capacitors ........................................................33
13.3.1
Charging the backup capacitor.........................34
13.3.2
Estimation of backup time with capacitor .........34
13.4
Diode selection.................................................35
14.
PCB layout guidelines ......................................36
15.
Partial circuit switch down ...............................38
16.
Hints to keep power consumption low ............ 39
17.
First period inaccuracy when using the timer 43
18.
Timing requirements for I
2
C read and write ....45
19.
Troubleshooting ................................................48
19.1
Oscillator startup time ......................................48
19.2
Checking for oscillation ....................................48
19.3
No communication via I
2
C-bus .........................49
19.4
Wrong time and date, wrong clock speed ........50
20.
References .........................................................50
21.
Legal information .............................................. 51
21.1
Definitions ........................................................ 51
21.2
Disclaimers ...................................................... 51
21.3
Trademarks...................................................... 51
22.
Contents............................................................. 52