Quartz MEMS usher smallest real-time clock

Epson Toyocom is claiming the smallest real-time clock chip fashioned by combining a quartz MEMS resonator with an ASIC. The chip was wire-bonded in the same 3.4mm x 1.7mm x 1mm package.

The RX-4571BD model uses a three-wire serial interface; the RX-8571BD uses NXP Semiconductor's I?C bus interface.

"These are the smallest footprint real-time clocks available today," claimed Michael Semos, product marketing engineer at Epson. The RX-4571BD consumes 43 percent less cubic volume while the RX-8571BD uses 52 percent less volume than previous real-time clocks.

Epson Toyocom's clock chip resonators are made by processing quartz wafers using photolithography, etching, metallization and sacrificial-layer removal—the same steps used to make silicon MEMS chips. Quartz is a piezoelectric material that naturally oscillates at a steady rate when activated with an electric current. Silicon MEMS chips require more signal conditioning to achieve equal performance.

Epson Toyocom's new platform oscillators combine a tiny, hermetically-sealed quartz crystal in the same package with the time-based ASIC.

The new clocks could be used in portable devices ranging from digital cameras and handheld medical devices to office and factory automation equipment. Their ultra-low standby power—as little as 0.22?A—allows the chips to keep time without using up battery power in portable devices.

- R. Colin Johnson
EE Times