DS1486/DS1486P

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DATA RETENTION

the RAMified Timekeeper will automatically write-protect itself and all inputs to the registers become

approximately 3.0 volts, a power switching circuit turns the internal lithium energy source on to maintain

the clock and timer data functionality. It is also required to insure that during this time (battery backup

of 200 ms.

RAMIFIED TIMEKEEPER REGISTERS

The RAMified Timekeeper has 14 registers which are 8 bits wide that contain all of the timekeeping,

alarm, watchdog and control information. The clock, calendar, alarm, and watchdog registers are memory

locations which contain external (user-accessible) and internal copies of the data. The external copies are

independent of internal functions except that they are updated periodically by the simultaneous transfer of

the incremented internal copy (see Figure 1). The Command Register bits are affected by both internal

and external functions. This register will be discussed later. Registers 0, 1, 2, 4, 6, 8, 9, and A contain

time of day and date information (see Figure 2). Time of day information is stored in BCD. Registers 3,

5, and 7 contain the Time of Day Alarm information. Time of Day Alarm information is stored in BCD.

Register B is the Command Register and information in this register is binary. Registers C and D are the

Watchdog Alarm Registers and information which is stored in these two registers is in BCD. Registers E

through 1FFFF are user bytes and can be used to maintain data at the user’s discretion.

CLOCK ACCURACY (DIP MODULE)

The DS1486 is guaranteed to keep time accuracy to within

±1 minute per month at 25°C.

CLOCK ACCURACY (POWERCAP MODULE)

The DS1486P and DS9034PCX are each individually tested for accuracy. Once mounted together, the

module is guaranteed to keep time accuracy to within ±1.53 minutes per month (35 ppm) at 25°C.