The DS1390/91/92/93 three- and four-wire serial-peripheral-interface bus real-time clocks feature automatic power switching, a trickle-charge output, an alarm, a microprocessor reset, a square-wave output, and a periodic interrupt signal all within a 10-pin small-outline package. The first two family members are designed for the four-wire bus, while the next two target the three-wire bus. Each clock monitors VCC and switches to backup power by write-protecting internal registers when power fails. The oscillators maintain timekeeping down to 1.3 V and consume 1 µA. All of the clocks operate from 40°C to 85°C. In quantities of 1000 units, they cost $1.25 each.
Maxim Integrated Products