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AN401 - Charging Methods for the F-RAM RTC Backup Capacitor | Cypress Semiconductor

AN401 - Charging Methods for the F-RAM RTC Backup Capacitor

Last Updated: 
Jun 07, 2021

AN401 describes the charging methods for the F-RAM RTC (FM31xxx/FM33xxx Processor Companion family) backup capacitor. A backup capacitor is used for backing up the real-time clock and event counters


The F-RAM real-time clock (RTC), which includes the FM31xxx/FM33xxx Processor Companion family devices, provide an option to backup RTC and event counters in the absence of system power through a backup power source (VBAK). VBAK can be either a battery or a capacitor. However, often a capacitor is preferred.

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