AN402 - F-RAM™ RTC Oscillator Design Guide

AN402 describes the real-time clock (RTC) oscillator and provides design considerations for using the RTC in the F-RAM™ processor companions.

Overview

The FM31xxx and FM33xxx are integrated processor companion devices that feature a real-time clock or RTC. The RTC provides the date and time information for the system. The RTC operates on VDD power and switches to a backup supply when the VDD power is removed. Under backup power, the RTC draws very little current, which allows a long operating time. The accuracy of the RTC is dependent mainly on the accuracy of the crystal oscillator. The crystal frequency is affected by the capacitive rating of the crystal and the operating temperature. This application note focuses on the RTC oscillator and provides design considerations for a system designer using these devices.