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DS1500YEN
Y2K Watchdog RTC with Nonvolatile Control
GENERAL DESCRIPTION The DS1500 is a full-function, year 2000-compliant
real-time clock/calendar (RTC) with an alarm, watchdog timer, power-on reset, battery monitors,
256 bytes of on-board nonvolatile (NV) SRAM, NV control for backing up an external SRAM, and a
32.768kHz output. User access to all registers within the DS1500 is accomplished with a byte-wide
interface, as shown in Figure 7. The RTC registers contain century, year, month, date, day, hours,
minutes, and seconds data in 24-hour binary-coded decimal (BCD) format. Corrections for day of month
and leap year are made automatically.
APPLICATIONS Remote Systems
Battery-Backed Systems Telecom Switches
Office Equipment Consumer Electronics
ORDERING INFORMATION
Selector Guide appears at end of data sheet. Typical Operating Circuit appears at end of data sheet.
FEATURES BCD-Coded Century, Year, Month, Date, Day,
Hours, Minutes, and Seconds with Automatic Leap-Year Compensation Valid Up to the Year
2100 Programmable Watchdog Timer and RTC Alarm Century Register; Y2K-Compliant RTC Automatic Battery Backup and Write Protection
to External SRAM +5V Operation Precision Power-On Reset Power-Control Circuitry Supports System Power-
On from Date/Day/Time Alarm or Key Closure 256 Bytes User NV RAM Auxiliary Battery Input Accuracy Better than ±1 Minute/Month at +25°C Day-of-Week/Date Alarm Register Battery Voltage-Level Indicator Flags Industrial Temperature Range: -40°C to +85°C
PIN CONFIGURATION
DS1500
Y2K Watchdog RTC with
Nonvolatile Control
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
ABSOLUTE MAXIMUM RATINGS Voltage Range on Any Pin Relative to Ground -0.5V to +6.0V
Operating Temperature Range -40°C to +85°C (Note 1)
Storage Temperature Range -55°C to +125°CSoldering Temperature See IPC/JEDEC J-STD-020A Specification
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only,
and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is
not implied. Exposure to the absolute maximum rating conditions for extended periods may affect device.
RECOMMENDED DC OPERATING CONDITIONS (TA = -40°C to +85°C)
DC ELECTRICAL CHARACTERISTICS (VCCMIN < VCCI < VCCMAX, TA = -40°C to +85°C.)
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
DC ELECTRICAL CHARACTERISTICS (VCC = 0V, TA = -40°C to +85°C.)
CRYSTAL SPECIFICATIONS* *The crystal, traces, and crystal input pins should be isolated from RF generating signals. Refer to Application Note 58: Crystal Considerations
for Dallas Real-Time Clocks for additional specifications.
AC OPERATING CHARACTERISTICS (VCCI = 5.0V �10%, TA = -40°C to +85°C.)
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
AC OPERATING CHARACTERISTICS (continued) (VCCI = 3.3V �10%, TA = -40°C to +85°C.)
Figure 1. Read Cycle Timing
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
Figure 2. Write Cycle Timing, Write-Enable-Controlled
Figure 3. Write Cycle Timing, Chip-Select-Controlled
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
Figure 4. Burst Mode Timing Waveform POWER-UP/DOWN CHARACTERISTICS (Figure 5)
CAPACITANCE
(TA = +25°C)
AC TEST CONDITIONS
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
Figure 5. 5V Power-Up/Down Waveform Timing
Warning: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery-backup mode.
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
WAKEUP/KICKSTART TIMING
(TA = +25°C) (Figure 6) Note: Time intervals shown above are referenced in Wakeup/Kickstart. Figure 6. Wakeup/Kickstart Timing Diagram
Note 1: Limits at -40°C are not production tested and are guaranteed by design.
Note 2: Voltage referenced to ground.
Note 3: Outputs are open.
Note 4: The IRQ, PWR, and RST outputs are open drain.
Note 5: Value for voltage and currents is from the VCCI input pin to the VCCO pin.
Note 6: If VPF is less than VBAT and VBAUX, the device power is switched from VCC to the greater of VBAT or VBAUX when VCC drops below VPF. If VPF
is greater than VBAT and VBAUX, the device power is switched from VCC to the greater of VBAT or VBAUX when VCC drops below the greater
of VBAT or VBAUX.
Note 7: Value for voltage and currents is from the VBAT or VBAUX input pin to the VCCO pin.
Note 8: IBAT1 and IBAT2 are specified with VCCO floating and do not include any RAM current.
Note 9: VBAT or VBAUX current. Using a 32,768Hz crystal connected to X1 and X2.
Note 10: These parameters are sampled with a 5pF load and are not 100% tested.
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
PIN DESCRIPTION
*See “Conditions of Acceptability” at /TechSupport/QA/ntrl.htm.
DS1500 Y2KC Watchdog RTC with Nonvolatile Control
Figure 7. Block Diagram Figure 8. Typical Crystal Layout
