Rainbow-electronics DS14287 Uživatelský manuál Strana 1

1 of 25 080400FEATURES Direct replacement for IBM AT computerclock/calendar Functionally compatible with theDS1285/DS1287 Available as chip (DS1

DS14285/DS1428710 of 25CONTROL REGISTERSThe DS14285/DS14287 has four control registers which are accessible at all times, even during theupdate cycle.

DS14285/DS1428711 of 25REGISTER BMSB

DS14285/DS1428712 of 25REGISTER 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) b

DS14285/DS1428713 of 25NONVOLATILE RAMThe 114 general purpose nonvolatile RAM bytes are not dedicated to any special function within theDS14285/DS1428

DS14285/DS1428714 of 25that bits which are set remain stable throughout the read cycle. All bits which are set (high) are clearedwhen read and new int

DS14285/DS1428715 of 25PERIODIC INTERRUPT RATE ANDSQUARE WAVE OUTPUT FREQUENCY Table 2SELECT BITS REGISTER ARS3 RS2 RS1 RS0tPI PERIODICINTERRUPT RATE

DS14285/DS1428716 of 25UPDATE-ENDED AND PERIODIC INTERRUPT RELATIONSHIP Figure 4

DS14285/DS1428717 of 25ABSOLUTE MAXIMUM RATINGS*Voltage on Any Pin Relative to Ground -0.5V to +7.0VStorage Temperature -40°C to +85°CSoldering Tempe

DS14285/DS1428718 of 25AC ELECTRICAL CHARACTERISTICS Over the operating rangePARAMETER SYMBOL MIN TYP MAX UNITS NOTESCycle tCYC225 DC nsPulse Width, D

DS14285/DS1428719 of 25DS14285 BUS TIMING FOR MOTOROLA INTERFACEDS14285/DS14287 BUS TIMING FOR INTEL INTERFACE WRITE CYCLE

DS14285/DS142872 of 25ORDERING INFORMATIONDS14285 RTC Chip; 24-pin DIPDS14285N RTC Chip; 24-pin DIP; Industrial Temp RangeDS14285S RTC Chip; 24-pin

DS14285/DS1428720 of 25DS14285/DS14287 BUS TIMING FOR INTEL INTERFACE READ CYCLEDS14285/DS14287 IRQ RELEASE DELAY TIMING

DS14285/DS1428721 of 25POWER-DOWN/POWER-UP TIMINGPOWER-DOWN/POWER-UP TIMINGPARAMETER SYMBOL MIN TYP MAX UNITS NOTESCS at VIH before Power-DowntPD0µsV

DS14285/DS1428722 of 25NOTES:1. All voltages are referenced to ground.2. All outputs are open.3. The MOT pin has an internal pull-down of 20 kΩ.4.

DS14285/DS1428723 of 25DS14285 24-PIN DIPPKG 24-PINDIM MIN MAXA IN.MM1.24531.621.27032.25B IN.MM0.53013.460.55013.97C IN.MM0.1403.560.1604.06D IN.

DS14285/DS1428724 of 25DS14285Q 28-PIN PLCCPKG 28-PINDIM MIN MAXA0.165 0.180A10.090 0.120A20.020 -B0.026 0.033B10.013 0.021C0.009 0.012D0.485 0.495D10

DS14285/DS1428725 of 25DS14287 REAL-TIME CLOCK PLUS RAMPKG 24-PINDIM MIN MAXA IN.MM1.32033.531.33533.91B IN.MM0.72018.290.74018.80C IN.MM0.3458.760

DS14285/DS142873 of 25For the DS14287 the internal lithium cell is electrically isolated from the clock and memory whenshipped from the factory. This

DS14285/DS142874 of 25R/ W (Read/Write Input) - The R/ W pin also has two modes of operation. When the MOT pin isconnected to VCC for Motorola timin

DS14285/DS142875 of 25In a typical application RESET can be connected to VCC. This connection will allow the DS14287 to go inand out of power fail w

DS14285/DS142876 of 25DS14285/DS14287 BLOCK DIAGRAM Figure 1

DS14285/DS142877 of 25POWER-DOWN/POWER-UP CONSIDERATIONSThe real time clock function will continue to operate and all of the RAM, time, calendar, and

DS14285/DS142878 of 25RTC ADDRESS MAPThe address map of the DS14285/DS14287 is shown in Figure 2. The address map consists of 114 bytesof user RAM, 10

DS14285/DS142879 of 25and alarm bytes are always accessible because they are double buffered. Once per second the 10 bytes areadvanced by 1 second and