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 DS1744 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 32k x 8 NV SRAM. User access to all registers within the DS1744 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 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 DS1744 also contains its own power-fail circuitry that 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 DS1747 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 512k x 8 nonvolatile static RAM. User access to all registers within the DS1747 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 DS1747 also contains its own power-fail circuitry that 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 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 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 DS1388 I²C real-time clock (RTC), supervisor, and EEPROM is a multifunction device that provides a clock/calendar, programmable watchdog timer, power-supply monitor with reset, and 512 bytes of EEPROM. The clock provides hundredths of seconds, seconds, minutes, and hours, and operates in 24-hour or 12-hour format with an AM/PM indicator. The calendar provides 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. A watchdog timer provides a reset for an unresponsive microprocessor. It is programmable in 10ms intervals from 0.01 to 99.99 seconds. A temperature-compensated voltage reference and comparator circuit monitors the status of VCC. If a primary power failure is detected, the device automatically switches to the backup supply and drives the reset output to the active state. The backup supply maintains time and date operation in the absence of VCC. When VCC returns to nominal levels, the reset is held low for a period to allow the power supply and processor to stabilize. The device also has a pushbutton reset controller, which debounces a reset input signal. The device is accessed through an I²C serial interface.ApplicationsNetwork-Interface CardsPoint-of-Sale EquipmentPortable InstrumentationWireless Equipment

The low-voltage serial-peripheral interface (SPI™) DS1390/DS1391/DS1394 and the low-voltage 3-wire DS1392/DS1393 real-time clocks (RTCs) are clocks/calendars that provide hundredths of a second, 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 an AM/PM indicator. One programmable time-of-day alarm is provided. A temperature-compensated voltage reference monitors the status of VCC and automatically disables the bus interface and switches to the backup supply if a power failure is detected. On the DS1390, a single open drain output provides a CPU interrupt or a square wave at one of four selectable frequencies. The DS1391 replaces the SQW/active-low INT pin with an active-low RST output/debounced input.The DS1390, DS1391, and DS1394 are programmed serially through an SPI-compatible, bidirectional bus. The DS1392 and DS1393 communicate over a 3-wire serial bus, and the extra pin is used for either a separate interrupt pin or an active-low RST output/debounced input.All five devices are available in a 10-pin µSOP package, and are rated over the industrial temperature range.ApplicationsEmbedded Time StampingGPS/Telematics DevicesHandheld DevicesMedical Devices

The low-voltage serial-peripheral interface (SPI™) DS1390/DS1391/DS1394 and the low-voltage 3-wire DS1392/DS1393 real-time clocks (RTCs) are clocks/calendars that provide hundredths of a second, 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 an AM/PM indicator. One programmable time-of-day alarm is provided. A temperature-compensated voltage reference monitors the status of VCC and automatically disables the bus interface and switches to the backup supply if a power failure is detected. On the DS1390, a single open drain output provides a CPU interrupt or a square wave at one of four selectable frequencies. The DS1391 replaces the SQW/active-low INT pin with an active-low RST output/debounced input.The DS1390, DS1391, and DS1394 are programmed serially through an SPI-compatible, bidirectional bus. The DS1392 and DS1393 communicate over a 3-wire serial bus, and the extra pin is used for either a separate interrupt pin or an active-low RST output/debounced input.All five devices are available in a 10-pin µSOP package, and are rated over the industrial temperature range.ApplicationsEmbedded Time StampingGPS/Telematics DevicesHandheld DevicesMedical Devices

The low-voltage serial-peripheral interface (SPI™) DS1390/DS1391/DS1394 and the low-voltage 3-wire DS1392/DS1393 real-time clocks (RTCs) are clocks/calendars that provide hundredths of a second, 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 an AM/PM indicator. One programmable time-of-day alarm is provided. A temperature-compensated voltage reference monitors the status of VCC and automatically disables the bus interface and switches to the backup supply if a power failure is detected. On the DS1390, a single open drain output provides a CPU interrupt or a square wave at one of four selectable frequencies. The DS1391 replaces the SQW/active-low INT pin with an active-low RST output/debounced input.The DS1390, DS1391, and DS1394 are programmed serially through an SPI-compatible, bidirectional bus. The DS1392 and DS1393 communicate over a 3-wire serial bus, and the extra pin is used for either a separate interrupt pin or an active-low RST output/debounced input.All five devices are available in a 10-pin µSOP package, and are rated over the industrial temperature range.ApplicationsEmbedded Time StampingGPS/Telematics DevicesHandheld DevicesMedical Devices

The low-voltage serial-peripheral interface (SPI™) DS1390/DS1391/DS1394 and the low-voltage 3-wire DS1392/DS1393 real-time clocks (RTCs) are clocks/calendars that provide hundredths of a second, 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 an AM/PM indicator. One programmable time-of-day alarm is provided. A temperature-compensated voltage reference monitors the status of VCC and automatically disables the bus interface and switches to the backup supply if a power failure is detected. On the DS1390, a single open drain output provides a CPU interrupt or a square wave at one of four selectable frequencies. The DS1391 replaces the SQW/active-low INT pin with an active-low RST output/debounced input.The DS1390, DS1391, and DS1394 are programmed serially through an SPI-compatible, bidirectional bus. The DS1392 and DS1393 communicate over a 3-wire serial bus, and the extra pin is used for either a separate interrupt pin or an active-low RST output/debounced input.All five devices are available in a 10-pin µSOP package, and are rated over the industrial temperature range.ApplicationsEmbedded Time StampingGPS/Telematics DevicesHandheld DevicesMedical Devices