DS1500 Maxim, DS1500 Datasheet
DS1500
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DS1500 Summary of contents
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... 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 ...
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... Soldering Temperature (reflow) 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 ...
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... PARAMETER Nominal Frequency Series Resistance Load Capacitance Note: The crystal, traces, and crystal input pins should be isolated from RF generating signals. Refer to Application Note 58: Crystal Considerations for Maxim Real-Time Clocks (RTCs) for additional specifications. AC OPERATING CHARACTERISTICS (V = 5.0V ±10 Over the Operating Range.) CCI ...
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AC OPERATING CHARACTERISTICS (continued 3.3V ±10 Over the Operating Range.) CCI A PARAMETER Read Cycle Time Address Access Time Low-Z CS Access Time CS Data Off Time Low-Z (0°C to ...
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Figure 2. Write Cycle Timing, Write-Enable-Controlled A0- DQ0-DQ7 Figure 3. Write Cycle Timing, Chip-Select-Controlled A0- DQ0-DQ7 t WC VALID WEW t WEZ DATA OUTPUT DATA INPUT t WC VALID t t ...
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Figure 4. Burst Mode Timing Waveform A0–A4 OE, WE DQ0–DQ7 POWER-UP/DOWN CHARACTERISTICS PARAMETER CS, CEI Before Power-Fail IH V Fall Time CCI PF(MAX) PF(MIN) V Fall Time CCI ...
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Figure 5. 5V Power-Up/Down Waveform Timing V CCI V PF(MAX) V PF(MIN RST INPUTS RECOGNIZED OUTPUTS VALID Warning: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery-backup mode. ...
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WAKEUP/KICKSTART TIMING (T = +25°C) (Figure 6) A PARAMETER Kickstart-Input Pulse Width Wakeup/Kickstart Power-On Timeout 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 ...
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... X1 and X2 pins. There is no need for external capacitors or resistors. An 12, 13 X1, X2 external 32.768kHz oscillator can also drive the DS1500. In this configuration, the X1 pin is connected to the external oscillator signal and the X2 pin is left unconnected. For more information about crystal selection and crystal layout considerations, refer to Application Note 58: Crystal Considerations with Maxim Real-Time Clocks (RTCs) ...
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... Figure 8. Typical Crystal Layout LOCAL GROUND PLANE (LAYER 2) CRYSTAL CLOCK ALARM AND WATCHDOG COUNTDOWN AND POWER-ON RESET X1 X2 GND IRQ SQW CLOCK AND CONTROL REGISTERS A0–A4 DQ0–DQ7 CS WE 256 SRAM Maxim DS1500 V CCO RST PWR CEO ...
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... DATA WRITE MODE The DS1500 is in write mode whenever CS and WE are in their active state. The start of a write is referenced to the latter occurring transition WE. The addresses must be held valid throughout the cycle must ...
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... All control, data, and address signals must be no more than 0.3V above V . CCI AUXILIARY BATTERY The V input is provided to supply power from an auxiliary battery for the DS1500 kickstart and square-wave BAUX output features in the absence applied to the device. CCI This auxiliary battery can be used as the primary backup power source for maintaining the clock/calendar and external SRAM ...
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... POWER-UP DEFAULT STATES These bits are set upon power-up: EOSC = 0, E32K = 0, TIE = 0, KIE = 0, WDE = 0, and WDS = 0. Note: Unless otherwise specified, the state of the control/RTC/SRAM bits in the DS1500 is not defined upon initial power application; the DS1500 should be properly configured/defined during initial configuration. ...
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... The alarm can be programmed to activate on a specific day of the month, day of the week, or repeat every day, hour, minute, or second. It can also be programmed to go off while the DS1500 is in the battery-backed state of operation to serve as a system wakeup. Alarm mask bits AM1 to AM4 control the alarm mode. Table 3 shows the possible settings ...
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... RAM memory or clock functions. These bits are read only. PRS, Reset Select Bit (0Eh Bit 5) When set to 0, the PWR pin is set high-Z when the DS1500 goes into power-fail. When set to 1, the PWR pin remains active upon entering power-fail. ...
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... TE bit is written to 0, any update transfer is inhibited and the program can initialize the time and calendar bytes without an update occurring in the midst of initializing. Read cycles can be executed in a similar manner read/write bit that is not modified by internal functions of the DS1500. CS, Crystal Select Bit (0Fh Bit 6) When CS is set to 0, the oscillator is configured for operation with a crystal that has a 6pF specified load capacitance ...
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... WDE = 1 and WDS = 1: WDF is set, the RST pin pulses low, and WDE resets to 0. WAKEUP/KICKSTART The DS1500 incorporates a wakeup feature, which powers predetermined date by activating the PWR output pin. In addition, the kickstart feature allows the system to be powered up in response to a low-going transition on the KS pin, without operating voltage applied to the V upon such events as key closure modem-ring-detects signal ...
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... At the beginning of Interval 3, the system processor has begun code execution and clears the interrupt condition of TDF and/or KSF by writing 0s to both of these control bits. As long as no other interrupt within the DS1500 is pending, the IRQ line is taken inactive once these bits are reset, and execution of the application software can proceed ...
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... RoHS status. PACKAGE TYPE 32 TSOP CRYSTAL RPU CCI PWR V CCO CEO RST IRQ SQW V BAUX CEI Maxim V A0–A4 BAT DS1500 CE GND GND PACKAGE CODE OUTLINE NO. Z32 SRAM LAND PATTERN NO. 21-0274 90-0320 ...
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... © 2011 Maxim Integrated Products DS1500 Y2K Watchdog RTC with Nonvolatile Control DESCRIPTION Maxim is a registered trademark of Maxim Integrated Products, Inc ...