DP8572A

Features:

 Full function real time clock/calendar
    - 12/24 hour mode timekeeping
    - Day of week and day of years counters
    - Four selectable oscillator frequencies
   - Parallel resonant oscillator
 Power fail features
  - Internal power supply switch to external battery
  - Power Supply Bus glitch protection
  - Automatic log of time into RAM at power failure
 On-chip interrupt structure
  - Periodic, alarm, and power fail interrupts
 Up to 44 bytes of CMOS RAM
 MIL-STD-883C compliant
 SMD Ý5962-91641-01MJX (future)


Pinout




Specifications

Supply Voltage (V_CC) .............................................-0.5V to a7.0V
DC Input Voltage (V_IN) ...................................-0.5V to VCC a0.5V
DC Output Voltage (V_OUT)............................. -0.5V to VCC a 0.5V
Storage Temperature Range............................... -65 to +150
Power Dissipation (P_D) ......................................................500 mW
Lead Temperature (Soldering, 10 sec.) .................................260

Description

The DP8572A (8572AMÐmilitarized version) is intended for use in microprocessor based systems where information is required for multi-tasking, data logging or general time of day/date information. DP8572A is implemented in low voltage silicon gate microCMOS technology to provide low standby power in battery back-up environments. The circuit's architecture is such that it looks like a contiguous block of memory or I/O ports. The address space is organized as 2 software selectable pages of 32 bytes. This includes the Control Registers, the Clock Counters, the Alarm Compare RAM, and the Time Save RAM. Any of the RAM locations that are not being used for their intended purpose may be used as general purpose CMOS RAM.

Time and date are maintained from 1/100 of a second to year and leap year in a BCD format, 12 or 24 hour modes. Day of week, day of month and day of year counters are provided. Time is controlled by an on-chip crystal oscillator requiring only the addition of the crystal and two capacitors. The choice of crystal frequency is program selectable.

Power failure logic and control functions of the DP8572A have been integrated on chip. This logic is used by the RTC to issue a power fail interrupt, and lock out the mp interface. The time power fails may be logged into RAM automatically when VBB >VCC. Additionally, two supply pins are provided. When VBB l VCC, internal circuitry will automatically switch from the main supply to the battery supply. Status bits are provided to indicate initial application of battery power, system
power, and low battery detect. (Continued)