Clock chip takes on supervisory functions

Xicor has added two new members to its integrated real time clock (RTC) product family.

Xicor has added two new members to its integrated real time clock (RTC) product family.

The X1288 combines real time clock/calendar functions and high-density (32K x 8bit) embedded EEPROM with advanced system management building blocks.

The X1286 offers the same advanced clock/calendar functions and embedded EEPROM, but without the supervisory functions.

Operating from 1.8-5.5V, these functions make these parts ideal for a wide range of embedded timekeeping applications.

In addition, the devices 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 the most commonly measured environmental parameter in embedded systems.

Accurate time and date monitoring is required in almost all systems.

For example, set top boxes need to monitor pay-per-view events for billing, and to monitor loss-of-signal events for maintenance.

Similarly, time and date stamping functions are needed within industrial utility meters to time stamp meter readings for billing, in medical equipment to time and date stamp critical readings to insure accurate diagnosis, in routers to time and date stamp message packets to meet quality of service levels, and in all-in-one printers and fax machines to time and date stamp fax transmissions and receptions.

The X1288 and X1286 feature a flexible alarm architecture that allows designers to preset time or calendar driven alarms.

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

The devices 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.

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

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

The output offers designers the choice of 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 by 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 stand-alone memory and reduce overall component count and system cost.

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 new members of Xicor's RTC family provide clock and calendar functions, memory and advanced supervisory functions in one device.

Samples and production quantities are now available.

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