FM33xx SPI Companion Design Guide

FM33xx SPI Companion Design Guide
AN408

FM33xx SPI Companion Design Guide
Applies to FM3316 and FM33256 Devices


OVERVIEW
The FM33256 and FM3316 products offer integrated Processor Companion, Real Time Clock (RTC),
and FRAM memory. The FM33xx family includes devices that have 256Kb and 16Kb of nonvolatile
FRAM memory. Both devices employ an industry standard SPI interface. This interface is used to
access the memory, the processor companion, and the RTC. The FM33xx operates over a 2.7V to
3.6V power supply range. Table 1 summarizes the product family and their key features.

Table 1. Summary of Part Types & Features
SPI
Part # Memory Companion RTC Voltage Freq Pack