DS1554

Features:

Integrated NV SRAM, real time clock, crystal,power-fail control circuit and lithium energy source 
Clock registers are accessed identically to the static RAM; these registers are resident in the 16 top RAM locations  Century byte register; i.e., Y2K complaint 
Totally nonvolatile with over 10 years of operation in the absence of power 
Precision power-on reset 
Programmable watchdog timer and RTC alarm 
BCD coded year, month, date, day, hours,minutes, and seconds with automatic leap year compensation valid up to the year 2100 
Battery voltage level indicator flag 
Power-fail write protection allows for ±10% V_CC power supply tolerance 
Lithium energy source is electrically disconnected to retain freshness until power is applied for the first time


Pinout




Specifications

Voltage on Any Pin Relative to Ground                                       -5.0V to +6.0V
Operating Temperature                                                                0°C to 70°C
Storage Temperature                                                            -55°C to +125°C
Soldering Temperature                                260°C for 10 seconds (See Note 8)


Description

The DS1554 is a full function, year 2000-compliant (Y2KC), real-time clock/calendar (RTC) with a RTC alarm, watchdog timer, power-on reset, battery monitor, and 32k x 8 non-volatile static RAM. User access to all registers within the DS1554 is accomplished with a bytewide interface as shown in Figure 1.

The RTC Registers DS1554 contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour BCD format. Corrections for day of month and leap year are made automatically. The RTC Registers DS1554 are double-buffered into an internal and external set. The user has direct access to the external set. Clock/calendar updates to the external set of registers can be disabled and enabled to allow the user to access static data. Assuming the internal oscillator is turned on, the internal set of registers are continuously updated; this occurs regardless of external registers settings to guarantee that accurate RTC information is always maintained.