Rainbow-electronics DS12887 Manual de usuario

1 of 19 073102Note: Some revisions of this device may incorporate deviations from published specifications known as errata. Multiple revisions of any

DS1288710 of 19changed. Therefore, the user should avoid interrupt service routines that would cause the time needed toread valid time/calendar data t

DS1288711 of 19REGISTERSThe DS12887 has four control registers that are accessible at all times, even during the update cycle.REGISTER AMSB LSBB

DS1288712 of 19REGISTER BMSB LSBBIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0SET PIE AIE UIE SQWE DM 24/12 DSESET – When the SET bit is a 0, t

DS1288713 of 19REGISTER CMSB LSBBIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0IRQF PF AF UF 0 0 0 0IRQF– The interrupt request flag (IRQF) bit

DS1288714 of 19ABSOLUTE MAXIMUM RATINGS*Voltage Range on Any Pin Relative to Ground -0.3V to +7.0VOperating Temperature Range 0°C to +70°CStorage Tem

DS1288715 of 19AC ELECTRICAL CHARACTERISTICS (VCC = 4.5V to 5.5V, 0°C to +70°C)PARAMETER SYMBOL MIN TYP MAX UNITS NOTESCycle Time tCY

DS1288716 of 19Figure 4. OUTPUT LOADFigure 5. BUS TIMING FOR MOTOROLA INTERFACE

DS1288717 of 19Figure 6. BUS TIMING FOR INTEL INTERFACE WRITE CYCLEFigure 7. BUS TIMING FOR INTEL INTERFACE READ CYCLE

DS1288718 of 19Figure 8. IRQ RELEASE DELAY TIMING

DS1288719 of 19Figure 9. POWER-UP/DOWN TIMINGPOWER-UP/DOWN TIMINGPARAMETER SYMBOL MIN TYP MAX UNITS NOTESCS at VIH before Power-DowntPD0msVCC Slew fr

DS128872 of 19TYPICAL OPERATING CIRCUITDESCRIPTIONThe DS12887 real-time clock (RTC) plus RAM is designed to be a direct replacement for the DS1287.The

DS128873 of 19Figure 1. BLOCK DIAGRAMPOWER-UP/DOWN CONSIDERATIONSThe RTC function continues to operate, and all of the RAM, time, calendar, and alarm

DS128874 of 19SIGNAL DESCRIPTIONSGND, VCC – DC power is provided to the device on these pins. VCC is the +5V input. When 5V areapplied within normal

DS128875 of 19cycle is terminated and the bus returns to a high-impedance state as DS transitions low in the case ofMotorola timing or as RD transit

DS128876 of 19RESET is low should exceed 200ms to ensure that the internal timer that controls the DS12887 on power-up has timed out. When RESET is

DS128877 of 19TIME, CALENDAR, AND ALARM LOCATIONSThe time and calendar information is obtained by reading the appropriate memory bytes. The time,calen

DS128878 of 19NV RAMThe 114 general-purpose NV RAM bytes are not dedicated to any special function within the DS12887.They can be used by the processo

DS128879 of 19OSCILLATOR CONTROL BITSWhen the DS12887 is shipped from the factory, the internal oscillator is turned off. This feature preventsthe lit