Clocks take memory and more onboard

Xicor has a three-member family of real time clock products that combine advanced real time clock/calendar, high density embedded EEPROM and advanced system management building block functions.

Xicor has a three-member family of real time clock (RTC) products that combine advanced real time clock/calendar, high density embedded EEPROM and advanced system management building block functions, simplifying design and saving onboard space.

The X1205 is the basic member of the family with advanced clock/calendar functions.

The X1286 offers the same clock/calendar functions and combines 256Kbit of embedded EEPROM.

The X1288 is the premier member of the family combining advanced clock/calendar functions, 256Kbit of embedded EEPROM and CPU supervisory functions.

The RTCs operate from 1.8-5.5V, making them ideal for a wide range of embedded timekeeping applications.

In addition, they include a battery switchover function that supports automatic switching from the main power supply to a battery backup in the event of power failure.

Time is a commonly measured environmental parameter in embedded systems.

Accurate time and date monitoring is required in almost all systems; set top boxes need to monitor "pay per view" events for billing, and need to monitor Oloss of signal' events for maintenance.

Industrial utility meters need to time stamp meter readings for billing, and medical equipment needs to time and date stamp critical readings to insure accurate diagnosis.

Similarly, routers need to time and date stamp message packets to meet quality of service levels, and all-in-one printers and fax machines need to time and date stamp fax transmissions and receptions.

The X1205, X1286 and X1288 have a variety of advanced features that facilitate control of time-based events.

A flexible alarm architecture allows designers to preset time or calendar driven alarms.

Alarms can be set with resolutions of sub-second, second, minute, hour, day, or month, or can be programmed for a specific day of the week.

The devices have an "on-chip oscillator compensation" feature that eliminates the need for an external RC circuit, improves the accuracy of the RTC, and provides ease of use for design engineers.

Additionally, these products feature a user-selectable frequency output option.

The output provides designers the flexibility of obtaining a square wave of 32.768kHz, 100Hz or 1Hz out of the real time clock.

The integrated real time clock products support the industry standard two-wire interface for direct control and communications to the real time clock/calendar and memory from a microcontroller.

Both the X1288 and X1286 contain 32K x 8bit of EEPROM.

This memory array can be used for phone book functions, calibration parameters, serialisation, general user memory, or any other function requiring byte addressable nonvolatile storage.

The embedded EEPROM can replace standalone memory and reduce overall component count and system cost.

The X1288 products have a complete set of integrated CPU supervisory functions, including watchdog timer, programmable low voltage detection circuits, and power-on-reset circuits.

The watchdog timer supports several user-selectable timeout intervals, ranging from 250ms to 1.75s.

Real time clock functions are standard building blocks required in laptop computers, cellular telephones, fax machines, utility meters and many other applications requiring time and date stamping of random events.

These applications stand to benefit from system level integration and the flexibility the on-chip compensation feature offers to improve clock accuracy without additional external components, thereby saving board space and cost.

Samples and production quantities of all of Xicor's RTC parts are now available.

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