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AN408 - A Design Guide to SPI F-RAM™ Processor Companion - FM33256B | Cypress Semiconductor

AN408 - A Design Guide to SPI F-RAM™ Processor Companion - FM33256B

Last Updated: 
Mar 02, 2021

AN408 provides an overview and design guidelines for the SPI F-RAM real-time clock (RTC) Processor Companion part - FM33256B. This document also includes a typical application, an example code, and a PSoC 3-based user module.


The FM33256B is a 256-Kbit serial (SPI) F-RAM memory product, which offers an integrated processor companion and an RTC. The processor companion section includes a power-on system reset, low-voltage detect, a watchdog timer, an early power-fail warning, an event counter, automatic switchover to backup power, and a lockable 64-bit serial number. It employs an industry-standard SPI, which is used to access the memory, the processor companion, and the RTC. The FM33256B operates over a 2.7 V-to-3.6 V power supply range with the maximum SPI frequency of 16 MHz. It is available in an SOIC-14 package.

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