(1 PC) DS12885 DALLAS SEMI Real Time Clock, Volatile, 1 Timer(s), CMOS, PDIP24

Description

DS12885/DS12885Q/DS12885T
Real-Time Clock
The  internal  oscillator  circuitry  is  designed  for  operation  with  a  crystal  having  a  specified
load  capacitance  (CL)  of  6pF
VBAT–Battery  input  for  any  standard  3V  lithium  cell  or  other  energy  source.  Battery  voltage  must  be  held  between  2.5V  and  4V  for  proper  operation.  A  maximum  load  of  0.5μA at +25°C in the absence of power   should   be   used   to   size   the   external   energy   source.   Maximum   load   is   measured   using   a recommended crystal type connected to X1 and X2.
FEATURES
Drop-in replacement for IBM AT computer clock/calendar
Pin configuration closely matches MC146818B and DS1285
Counts seconds, minutes, hours, days, day of the week, date, month, and year with leap-year compensation valid up to 2100
Binary or BCD representation of time, calendar, and alarm
12-hour or 24-hour clock with AM and PM in 12-hour  mode
Daylight Savings Time option
Selectable between Motorola and Intel bus timing
Multiplex bus for pin efficiency
Interfaced with software as 128 RAM locations
14 bytes of clock and control registers
114 bytes of general purpose RAM
Programmable square-wave output signal bus-compatible interrupt signals (IRQ)
Three interrupts are separately software-maskable and testable
Time-of-day alarm once/second to once/day
Periodic rates from 122μs to 500ms
End-of-clock update cycle
Optional 28-pin PLCC surface mount package or 32-pin  TQFP
Optional industrial temperature range available
Underwriters Laboratory (UL) recognized
X1,  X2  –Connections  for  a  standard
32.768kHz  quartz  crystal.
The  internal  oscillator  circuitry  is  designed  for  operation  with  a  crystal  having  a  specified
load  capacitance  (CL)  of  6pF.
The  crystal  is  connected  directly  to  the  X1  and  X2  pins.  There  is  no  need  for  external  capacitors or resistors. Note: X1 and X2 are very high-impedance nodes. It is recommended that they and the crystal be guard-ringed with ground  and  that  high-frequency  signals  be  kept  away  from  the  crystal  area.  For  more  information  about  crystal  selection  and  crystal  layout  considerations,  refer  to  Application Note 58 “Crystal Considerations with Dallas Real Time Clocks.”