The DS1557 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) with an RTC alarm, watchdog timer, power-on reset, battery monitor, and 512k x 8 nonvolatile static RAM. User access to all registers within the DS1557 is accomplished with a byte-wide interface as shown in Figure1. The RTC registers 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 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 is continuously updated; this occurs regardless of external registers settings to guarantee that accurate RTCinformation is always maintained.The DS1557 has interrupt (active-low IRQ/FT) and reset (active-low RST) outputs which can be used to control CPU activity.The (active-low IRQ/FT) interrupt output can be used to generate an external interrupt when the RTC register values match user programmed alarm values. The interrupt is always available while the device is powered from the system supply and can be programmed to occur when in the battery-backed state to serve as a system wakeup. Either the active-low IRQ/FT or active-low RST outputs can also be used as a CPU watchdog timer, CPU activity ismonitored and an interrupt or reset output will be activated if the correct activity is not detected within programmed limits. The DS1557 power-on reset can be used to detect a system power down or failure and hold the CPU in a safe reset state until normal power returns and stabilizes; the active-low RST output is used for this function.The DS1557 also contains its own power-fail circuitry, which automatically deselects the device when the VCC supply enters an out-of-tolerance condition. This feature provides a high degree of data securityduring unpredictable system operation brought on by low VCC levels.

The DS1558 is a full function, year 2000-compliant (Y2KC), real-time clock/calendar with an RTC alarm, watchdog timer, power-on reset, battery monitor, and NV SRAM controller. User access to all registers within the DS1558 is accomplished with a byte-wide interface as shown in Figure 1. The RTC registers 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 DS1558 maps the RTC registers into the SRAM address space and constantly monitors A0-A18. When any of the upper 16 address locations are accessed, the DS1558 inhibits active-low CER and active-low OER to the SRAM, and redirects reads and writes to the RTC registers within the DS1558. The DS1558 can be used with SRAMs up to 524,272 addresses. Smaller SRAMs can be used, provided that the unused upper address lines on the DS1558 are connected to VCC.The RTC registers 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 is continuously updated; this occurs regardless of external register settings to guarantee that accurate RTC information is always maintained.The DS1558 has interrupt (active-low IRQ/FT) and reset (active-low RST) outputs that can be used to control CPU activity. The active-low IRQ/FT interrupt output can generate an external interrupt when the RTC register values match user-programmed alarm values. The interrupt is always available while the device is powered from the system supply, and it can be programmed to occur when in the battery-backed state to serve as a system wake-up. The active-low IRQ/FT output can also be used as a CPU watchdog timer. CPU activity is monitored and an interrupt or reset output is activated if the correct activity is not detected within programmed limits. The DS1558 power-on reset can be used to detect a system power-down or failure and hold the CPU in a safe reset state until normal power returns and stabilizes; the active-low RST output is used for this function.The DS1558 also contains its own power-fail circuitry, which automatically protects the data in the clock and SRAM against out-of-tolerance VCCI conditions by inhibiting the active-low CE input when the VCC supply enters an out-of-tolerance condition. When VCCI goes below the level of VBAT, the external battery is switched on to supply energy to the clock and the external SRAM. This feature provides a high degree of data security during unpredictable system operation brought on by low VCC levels.

The DS1685/DS1687 are real-time clocks (RTCs) designed as successors to the industry-standard DS1285,DS1385, DS1485, and DS1585 PC RTCs. These devices provide the industry-standard DS1285 clock function with either +3.0V or +5.0V operation. The DS1685 also incorporates a number of enhanced features including a silicon serial number, power-on/off control circuitry, 242 bytes of user NV SRAM, and 32.768kHz output for sustaining power management activities.The DS1685/DS1687 power-control circuitry allows the system to be powered on by an external stimulus such as a keyboard or by a time and date (wake-up) alarm. The PWR output pin can be triggered by one or either of these events, and can be used to turn on an external power supply. The PWR pin is under software control, so that when a task is complete, the system power can then be shut down.The DS1685 is a clock/calendar chip with the features described above. An external crystal and battery are the only components required to maintain time-of-day and memory status in the absence of power. The DS1687 incorporates the DS1685 chip, a 32.768kHz crystal, and a lithium battery in a complete, self-contained timekeeping EDIP. The entire unit is fully tested at Dallas Semiconductor such that a minimum of 10 years of timekeeping and data retention in the absence of VCC is guaranteed.ApplicationsEmbedded SystemsNetwork Hubs, Switches, RoutersSecurity SystemsUtility Meters

The DS1685/DS1687 are real-time clocks (RTCs) designed as successors to the industry-standard DS1285,DS1385, DS1485, and DS1585 PC RTCs. These devices provide the industry-standard DS1285 clock function with either +3.0V or +5.0V operation. The DS1685 also incorporates a number of enhanced features including a silicon serial number, power-on/off control circuitry, 242 bytes of user NV SRAM, and 32.768kHz output for sustaining power management activities.The DS1685/DS1687 power-control circuitry allows the system to be powered on by an external stimulus such as a keyboard or by a time and date (wake-up) alarm. The PWR output pin can be triggered by one or either of these events, and can be used to turn on an external power supply. The PWR pin is under software control, so that when a task is complete, the system power can then be shut down.The DS1685 is a clock/calendar chip with the features described above. An external crystal and battery are the only components required to maintain time-of-day and memory status in the absence of power. The DS1687 incorporates the DS1685 chip, a 32.768kHz crystal, and a lithium battery in a complete, self-contained timekeeping EDIP. The entire unit is fully tested at Dallas Semiconductor such that a minimum of 10 years of timekeeping and data retention in the absence of VCC is guaranteed.ApplicationsEmbedded SystemsNetwork Hubs, Switches, RoutersSecurity SystemsUtility Meters

The DS1685/DS1687 are real-time clocks (RTCs) designed as successors to the industry-standard DS1285,DS1385, DS1485, and DS1585 PC RTCs. These devices provide the industry-standard DS1285 clock function with either +3.0V or +5.0V operation. The DS1685 also incorporates a number of enhanced features including a silicon serial number, power-on/off control circuitry, 242 bytes of user NV SRAM, and 32.768kHz output for sustaining power management activities.The DS1685/DS1687 power-control circuitry allows the system to be powered on by an external stimulus such as a keyboard or by a time and date (wake-up) alarm. The PWR output pin can be triggered by one or either of these events, and can be used to turn on an external power supply. The PWR pin is under software control, so that when a task is complete, the system power can then be shut down.The DS1685 is a clock/calendar chip with the features described above. An external crystal and battery are the only components required to maintain time-of-day and memory status in the absence of power. The DS1687 incorporates the DS1685 chip, a 32.768kHz crystal, and a lithium battery in a complete, self-contained timekeeping EDIP. The entire unit is fully tested at Dallas Semiconductor such that a minimum of 10 years of timekeeping and data retention in the absence of VCC is guaranteed.ApplicationsEmbedded SystemsNetwork Hubs, Switches, RoutersSecurity SystemsUtility Meters

The DS17285, DS17485, DS17885, DS17287, DS17487, and DS17887 real-time clocks (RTCs) are designed to be successors to the industry-standard DS12885 and DS12887. The DS17285, DS17485, and DS17885 (hereafter referred to as the DS17x85) provide a real-time clock/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programmable square wave, and 114 bytes of battery-backed NV SRAM. The DS17x85 also incorporates a number of enhanced functions including a silicon serial number, power-on/off control circuitry, and 2K, 4K, or 8Kbytes of battery-backed NV SRAM. The DS17287, DS17487, and DS17887 (hereafter referred to as the DS17x87) integrate a quartz crystal and lithium energy source into a 24-pin encapsulated DIP package. The DS17x85 and DS17x87 power-control circuitry allows the system to be poweredon by an external stimulus such as a keyboard or by a time-and-date (wake-up) alarm. The active-low PWR output pin is triggered by one or either of these events, and is used to turn on an external power supply. The active-low PWR pin is under software control, so that when a task is complete, the system power can then be shut down.For all devices, the date at the end of the month is automatically adjusted for months with fewer than 31 days, including correction for leap years. It also operates in either 24-hour or 12-hour format with an AM/PM indicator. A precision temperature-compensated circuit monitors the status of VCC. If a primary power failure is detected, the device automatically switches to a backup supply. A lithium coin cell battery can be connected to the VBAT input pin on the DS17x85 to maintain time and date operation when primary power is absent. The DS17x85 and DS17x87 include a VBAUX input used to power auxiliary functions such as active-low PWR control. The device is accessed through a multiplexed byte-wide interface.ApplicationsEmbedded SystemsNetwork Hubs, Bridges, and RoutersSecurity SystemsUtility Meters

The DS1746 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 128k x 8 nonvolatile static RAM. User access to all registers within the DS1746 is accomplished with a byte-wide interface as shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations. The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour binary-coded decimal (BCD) format. Corrections for the date of each month and leap year are made automatically. The RTC clock registers are double buffered to avoid access of incorrect data that can occur during clock update cycles. The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by access to time register data. The DS1746 also contains its own power-fail circuitry, which deselects the device when the VCC supply is in an out of tolerance condition. This feature prevents loss of data from unpredictable system operation brought on by low VCC as errant access and update cycles are avoided.

The DS1315 Phantom Time Chip is a combination of a CMOS timekeeper and a nonvolatile memory controller. In the absence of power, an external battery maintains the timekeeping operation and provides power for a CMOS static RAM. The watch keeps track of hundredths of seconds, seconds, minutes, hours, day, date, month, and year information. The last day of the month is automatically adjusted for months with less than 31 days, including leap year correction. The watch operates in one of two formats: a 12-hour mode with an AM/PM indicator or a 24-hour mode. The nonvolatile controller supplies all the necessary support circuitry to convert a CMOS RAM to a nonvolatile memory. The DS1315 can be interfaced with either RAM or ROM without leaving gaps in memory.

The DS3232 is a low-cost temperature-compensated crystal oscillator (TCXO) with a very accurate, temperature-compensated, integrated real-time clock (RTC) and236 bytes of battery-backed SRAM. Additionally, the DS3232 incorporates a battery input and maintains accurate timekeeping when main power to the device is interrupted. The integration of the crystal resonator enhances the long-term accuracy of the device as well as reduces the piece-part count in a manufacturing line. The DS3232 is available in commercial and industrial temperature ranges, and is offered in an industry-standard 20-pin, 300-mil SO package.The RTC maintains seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. Theclock operates in either the 24-hour or 12-hour format with an active-low AM/PM indicator. Two programmable time-of-day alarms and a programmable square-wave output are provided. Address and data are transferred serially through an I²C bidirectional bus.A precision temperature-compensated voltage reference and comparator circuit monitors the status of VCC to detect power failures, to provide a reset output, and to automatically switch to the backup supply when necessary.Additionally, the active-low RST pin is monitored as a pushbutton input for generating a µP reset.ApplicationsGPSServersTelematicsUtility Power Meters

Delay Lines/Timing Elements Programmable 8-Bit 1ns Delay Line