Real-time clock reduces board space

A new real-time clock with a CPU supervisor and non-volatile SRAM offers designers a device that requires less than 50% of the board space of a traditional through-hole device.

A new real-time clock with a CPU supervisor and non-volatile SRAM control from Texas Instruments offers designers a device that requires less than 50% of the board space of a traditional through-hole device and 45% less space than surface mount solutions.

The new bq4802 device integrates a time-of-day clock and a century-based calendar and is offered in a variety of packages with a two-piece SNAPHAT module, making it ideal for tele- and data-communications applications, such as routers, hubs, ISP servers, cell phone base stations and network controllers.

With the use of conditioned chip-enable output and battery voltage output pins, the bq4802 can write-protect and create nonvolatile external SRAMs of any density. The device contains a backup cell to power the real-time clock while maintaining valid SRAM information without the use of a system supply voltage.

The bq4802 also provides direct connection for a 32.768kHz quartz crystal and a 3V backup battery, which are placed in the SNAPHAT package on top. Additional features of the device include a built-in watchdog timer that monitors the processor operation and can generate a system reset if an error occurs as well as further system interrupts based on a clock alarm or periodic alarm settings.

The bq4802 is available now from TI and its authorised distributors and can be ordered in a 5.0V or 3.3V version and in a 28-pin SOIC or 28-pin TSSOP package.

The variety of packages will be extended with the SNAPHAT version, which is planned to be available in 1Q 2002. To complete the SNAPHAT module, the bq48SH-28×6, which houses the backup battery and RTC crystal, is required.

Suggested resale pricing for the bq4802 IC starts at $2.35 in quantities of 1,000. The two-piece SNAPHAT module will be available starting from $7.00 in quantities of 1,000.

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