The DS1673 portable system controller is a circuit that incorporates many of the functions necessary for low-power portable products integrated into one chip. The device provides a real-time clock (RTC), NV RAM controller, microprocessor monitor, and a 3-channel, 8-bit analog-to-digital converter (ADC). Communication with the DS1673 is established through a simple 3-wire interface.The RTC provides seconds, minutes, hours, day, date, month, and year information with leap year compensation. The RTC also provides an alarm interrupt. This interrupt works when the DS1673 is powered by the system power supply or when in battery-backup operation, so the alarm can be used to wake up a system that is powered down.Automatic backup and write protection of an external SRAM is provided through the VCCO, active-low CEOL, and active-low CEOH pins. The backup energy source used to power the RTC is also used to retain RAM data in the absence of VCC through the VCCO pin. The chip-enable outputs to RAM (active-low CEOL and active-low CEOH) are controlled during power transients to prevent data corruption.

The DS1135L series is a low-power, 3V high-speed version of the popular DS1013, DS1033, and DS1035 series.The DS1135L series of delay lines have three independent logic buffered delays in a single package. The device is our fastest 3-in-1 delay line. It is available in a 150-mil 8-pin SO.The device features precise leading and trailing edge accuracy. It has the inherent reliability of an all-silicon delay line solution.Standard delay values are indicated in Table 1 in the full data sheet.

The DS1251 4096K NV SRAM with Phantom Clock is a fully static nonvolatile RAM (organized as 512K words by 8 bits) with a built-in real-time clock. The DS1251Y has a self-contained lithium energy source and control circuitry which constantly monitors VCC for an out-of-tolerance condition. When such a condition occurs, the lithium energy source is automatically switched on and write protection is unconditionally enabled to prevent garbled data in both the memory and real-time clock.The Phantom Clock provides timekeeping information including hundredths of seconds, seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with less than 31 days, including correction for leap years. The Phantom Clock operates in either 24-hour or 12-hour format with an AM/PM indicator.

The DS12885, DS12887, and DS12C887 real-time clocks (RTCs) are designed to be direct replacements for the DS1285 and DS1287. The devices 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 static RAM (113 bytes in the DS12C887 and DS12C887A). The DS12887 integrates a quartz crystal and lithium energy source into a 24-pin encapsulated DIP package. The DS12C887 adds a century byte at address 32h. 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. The devices also operate 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 DS12885 to maintain time and date operation when primary power is absent. The device is accessed through a multiplexed byte-wide interface, which supports both Intel and Motorola modes.ApplicationsEmbedded SystemsNetwork Hubs, Bridges, and RoutersSecurity SystemsUtility Meters

The DS12885, DS12887, and DS12C887 real-time clocks (RTCs) are designed to be direct replacements for the DS1285 and DS1287. The devices 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 static RAM (113 bytes in the DS12C887 and DS12C887A). The DS12887 integrates a quartz crystal and lithium energy source into a 24-pin encapsulated DIP package. The DS12C887 adds a century byte at address 32h. 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. The devices also operate 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 DS12885 to maintain time and date operation when primary power is absent. The device is accessed through a multiplexed byte-wide interface, which supports both Intel and Motorola modes.ApplicationsEmbedded SystemsNetwork Hubs, Bridges, and RoutersSecurity SystemsUtility Meters

The DS1306 serial alarm real-time clock (RTC) provides a full binary coded decimal (BCD) clock calendar that is accessed by a simple serial interface. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. In addition, 96 bytes of NV RAM are provided for data storage.An interface logic-power supply input pin (VCCIF) allows the DS1306 to drive SDO and 32kHz pins to a level that is compatible with the interface logic. This allows an easy interface to 3V logic in mixed supply systems. The DS1306 offers dual-power supplies as well as a battery-input pin. The dual-power supplies support a programmable trickle charge circuit that allows a rechargeable energy source (such as a super cap or rechargeable battery) to be used for a backup supply. The VBAT pin allows the device to be backed up by a non-rechargeable battery. The DS1306 is fully operational from 2.0V to 5.5V.Two programmable time-of-day alarms are provided by the DS1306. Each alarm can generate an interrupt on a programmable combination of seconds, minutes, hours, and day. 'Don't care' states can be inserted into one or more fields if it is desired for them to be ignored for the alarm condition. A 1Hz and a 32kHz clock output are also available.The DS1306 supports a direct interface to SPI™ serial data ports or standard 3-wire interface. An easy-to use address and data format is implemented in which data transfers can occur 1-byte at a time or in multiple-byte Burst Mode®.

The DS1339 serial real-time clock (RTC) is a low-power clock/date device with two programmable time-of-day alarms and a programmable square-wave output. Address and data are transferred serially through an I²C bus. The clock/date provides 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. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The DS1339 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply, maintaining time, date, and alarm operation.ApplicationsConsumer Electronics (Set-Top Box, Digital Recording, Network Appliance)Handhelds (GPS, POS Terminal)Medical (Glucometer, Medicine Dispenser)Office Equipment (Fax/Printer, Copier)Other (Utility Meter, Vending Machine, Thermostat, Modem)Telecommunications (Router, Switcher, Server)

The DS1556 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 128k x 8 nonvolatile static RAM. User access to all registers within the DS1556 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 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, which occurs regardless of external registers settings to guarantee that accurate RTC information is always maintained.The DS1556 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 wake-up. Either the active-low IRQ/FT or active-low RST outputs can also be used as a CPU watchdog timer, CPU activity is monitored and an interrupt or reset output will be activated if the correct activity is not detected within programmed limits. The DS1556 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 DS1556 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 security during unpredictable system operation brought on by low VCC levels.

The DS1556 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 128k x 8 nonvolatile static RAM. User access to all registers within the DS1556 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 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, which occurs regardless of external registers settings to guarantee that accurate RTC information is always maintained.The DS1556 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 wake-up. Either the active-low IRQ/FT or active-low RST outputs can also be used as a CPU watchdog timer, CPU activity is monitored and an interrupt or reset output will be activated if the correct activity is not detected within programmed limits. The DS1556 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 DS1556 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 security during 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.