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| F-RAM and MCU Application Notes |
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| AN1XX = |
Parallel F-RAM Memories |
| AN2XX = |
Serial 2-Wire F-RAM Memories |
| AN3XX = |
Serial SPI F-RAM Memories |
| AN4XX = |
Processor Companions |
| AN5XX = |
Versa 8051 Microcontrollers |
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AN100 - Replacing SRAM with F-RAM
08/01/2000
 (45 KB)
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| When designing with F-RAM for the first time, users of SRAM will recognize a few minor differences. This document explains. |
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AN101 - A Single Memory for Code & Data Ruminations on design & applications
08/23/2000
(47 KB)
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| Applications for memory technologies generally are divided between executable code and data tasks. ROM-based technologies are nonvolatile and are oriented toward code applications. These include mask-ROM, OTP-EPROM, and Flash. EEPROM, another derivative of ROM technology, serves primarily as a nonvolatile data memory. |
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AN103 - 32 pin TSOP Pinouts
06/28/2007
(53 KB)
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| The FM18L08 (32Kx8) and FM20L08 (128Kx8) devices are offered in the 32-pin TSOP-I package. The package body size is a 8.0 x 13.4 mm and the pin pitch is 0.5 mm. The two devices are not pin compatible with each other, but they are compatible with the industry standard pinouts at their respective densities. This document explains further. |
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AN106 – Migrating from the FM20L08 to FM28V100
06/02/2009
(22 KB)
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| The FM20L08 (128Kx8) and FM28V100 (128Kx8) devices are offered in the 32-pin TSOP-I package. The two devices are not pin compatible with each other, but they are very similar. It is possible to design a pc board such that either device can populate the board. |
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AN108 – Differences between FM18L08 and FM28V020
09/21/2009
(28 KB)
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| This document points out the differences the FM18L08 and FM28V020 parallel F-RAM devices. For most designs, the FM28V020 device can be considered equivalent or better than the FM18L08. The application note explains further. (Updated Sept 2009) |
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AN109 – Differences between FM20L08 and FM28V100
06/01/2009
(27 KB)
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| This document points out the differences the FM20L08 and FM28V100 parallel F-RAM devices. For most designs, the FM28V100 device can be considered equivalent or better than the FM20L08. The application note explains further. |
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AN200 - Advantages of Using the FM24C16
01/21/1999
(33 KB)
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| The FM24C16 is a drop-in replacement for industry standard 24C16-type EEPROMs. Instead of using EEPROM as a storage mechanism, the FM24C16 uses F-RAM technology. This technology enables unique feature advantages. |
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AN201 - Interrupting a 2-Wire Read
03/22/1999
(43 KB)
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| The industry standard 2-wire bus is a robust protocol for a variety of applications. Unfortunately, it has one limitation that system developers may encounter. Interrupting a memory read in progress may be difficult. The 2-wire protocol does not offer a graceful method to accomplish this. This situation is not unique to the serial F-RAM devices, but this application note explains the method for clearing the condition. |
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AN202 - Microchip MCU to 2-Wire F-RAM
02/01/2003
(63 KB)
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| This application note provides source code to interface Microchip microcontrollers to Ramtron 2-wire F-RAM devices. Although the specific example uses a Microchip PIC16X7x and PIC16C8x with the FM24C04 memory, it is intended to be useful for other Microchip devices as well. |
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AN203 - Dual Footprint for the FM24C256
04/01/2003
(72 KB)
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| Ramtron manufactures 256K serial F-RAM products that are offered in both the 20-pin and 8-pin SOP. The FM24C256 was first introduced in a 20-pin SOP and is migrating to the 8 pin SOP package in order to reduce footprint size, provide compatibility with EEPROMs, and to lower cost. |
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AN204 - Differences in FM24Cxx and FM24CxxA
05/01/2004
(14 KB)
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| There are differences between “A” and “non-A” two-wire 4Kb and 16Kb F-RAM devices. The FM24C04 and FM24C16 memory devices operate up to 400kHz, whereas the FM24C04A and FM24C16A operate at speeds up to 1MHz. |
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AN206 – Differences between FM24L256 and FM24V02
06/01/2009
(74 KB)
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| This document points out the differences the FM24L256 and FM24V02 I2C F-RAM devices. For most designs, the FM24V02 device can be considered equivalent or better than the FM24L256. The application note explains further. |
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AN300 - SPI F-RAM SPI Bus Compatibility Note
01/06/1999
(64 KB)
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| The FM25160 uses an industry standard SPI interface. Users that intend the FM25160 as a drop-in replacement of an EEPROM may experience some difficulty in development. This application note summarizes the minor differences between the FM25160 and similar configuration EEPROM devices. It provides simple guidelines to modify the system design for proper operation. |
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AN301 - Difference in FM25160 and FM25C160
01/01/2005
(25 KB)
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| This application note describes the differences between the FM25160 and FM25C160 SPI 16Kb F-RAM devices. The FM25160 operates up to 1.8MHz and supports Mode 0 clocking, whereas the FM25C160 operates at speeds up to 20MHz and supports Modes 0 and 3. |
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AN302 - F-RAM SPI Reads & Writes and Data Protection During Power Cycles
06/01/2006
(81 KB)
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| This application note describes the internal operation of Ramtron’s high speed SPI devices and also offers some system design suggestions to avoid data corruption. |
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AN303 - Differences between FM25CL04 vs FM25L04
02/10/2006
(32 KB)
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| There are differences between the FM25CL04 and FM25L04 SPI 4Kb F-RAM devices. As of May 2005, the FM25CL04 was not recommended for new designs, and the replacement device is the FM25L04. |
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AN304 - Guide to SPI F-RAM
09/30/2009
(94 KB)
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| This application note provides a functional description of the SPI F-RAM Device, as well as practical information on timing specifications of the memory device and examples of pseudo code. Updated text and tables with new FM25V10/V05/V02 F-RAM devices. Added 3-byte addressing pseudo-code examples. |
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AN305 - Differences FM25256 vs FM25256B
06/09/2007
(19 KB)
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| This application note addresses the differences between FM25256 and FM25256B 5V SPI 256Kb F-RAM devices. The FM25256 is “not recommended for new designs” and has been replaced by the FM25256B. |
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AN306 - Differences in FM25L256 and FM25L256B
08/01/2007
(20 KB)
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| There are differences between the FM25L256 and FM25L256B 3V SPI 256Kb FRAM devices. As of March 2007, the FM25L256 was declared “not recommended for new designs”, and the alternative device is the FM25L256B device. |
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AN307 - Differences in FM25040 and FM25040A
09/06/2007
(34 KB)
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| This application note addresses the differences between FM25040 and FM25040A SPI 4Kb F-RAM devices. The FM25040 was obsoleted in December 2004 and has been replaced by the FM25040A. Functionally the two devices are the same, and system firmware should be compatible between the two devices. However the system designer should take note of the differences in the input ESD structures between the two. |
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AN308 – Differences between FM25L256B and FM25V02
06/01/2009
(27 KB)
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| This document points out the differences the FM25L256B and FM25V02 SPI F-RAM devices. For most designs, the FM25V02 device can be considered equivalent or better than the FM25L256B. The application note explains further. |
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AN309 – Differences between FM25L512 and FM25V05
06/01/2009
(27 KB)
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| This document points out the differences the FM25L512 and FM25V05 SPI F-RAM devices. For most designs, the FM25V05 device can be considered equivalent or better than the FM25L512. The application note explains further. |
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AN400 - Generating a Power-Fail Interrupt
09/01/2003
(42 KB)
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| The FM31xx Integrated Processor Companion family features a general purpose comparator that can be used to generate an early power-fail warning. This application note how to generate a power-fail inturrupt. |
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AN401 - Capacitor Backup
09/01/2003
(23 KB)
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| Using a capacitor to backup a real-time clock in the absence of system power is often preferable to a battery. This application note illustrates three simple methods of charging the capacitor. |
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AN402 - RTC Oscillator Guide
11/01/2003
(34 KB)
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| A real time clock (RTC) is incorporated on the FM31xx, FM3808, and FM30C256 F-RAM devices. This guide describes the crystal oscillator, how to measure its frequency, and also covers crystal selection and board layout issues. |
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AN403 - RTC Crystals - 6pF vs 12pF
01/28/2006
(80 KB)
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| This application note focuses on the use of 6pF vs. 12.5pF crystals for the RTC oscillator found in the FM31xx, FM4005, FM30C256, and FM3808. |
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AN404 - RTC Backup & UL Compliance
08/11/2007
(35 KB)
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| The FM31xx and FM4005 are Processor Companion devices that feature a real-time clock (RTC). This application note discusses the backup power sources, the internal charging circuit, and associated issues. |
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AN405 - Comparing FM31xx and FM3127x
12/01/2007
(39 KB)
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| This documents compares the FM31xx and FM3127x/FM31L27x I2C Processor Companion with F-RAM devices. |
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AN406 - Comparing FM32xx and FM3227x
03/20/2008
(28 KB)
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| This documents compares the FM32xx and FM3227x/FM32L27x I2C Processor Companion with F-RAM devices. |
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AN407 - FM3127x Design Guide
10/27/2008
(115 KB)
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| This application note provides a typical application system hookup, practical considerations of the RTC's backup power, selecting external components, and examples of I2C pseudo code. |
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AN408 - FM33xx Design Guide
09/22/2009
(118 KB)
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| This application note provides a typical application system hookup, practical considerations of the RTC's backup power, selecting external components, and examples of SPI pseudo code. |
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AN500 - System Design Notes for the VRS51L2070
10/28/2006
(501 KB)
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| This application note provides practical information for system designers developing hardware products based on the VRS51L2070. |
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AN501 - VRS51L2070/3074: Benefits of an Arithmetic Unit in FIR Filtering
10/25/2006
(84 KB)
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| This application note offers a performance comparison between Ramtron’s advanced Versa 8051 microcontrollers and industry standard 8051 MCUs when executing digital signal processing (DSP) operations. |
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AN502 - How to Run a 5V Character LCD Interface with a VRS51L2070
10/25/2006
(140 KB)
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| This application note explains how to operate a standard 5-volt character LCD module in a 3.3 volt system based on Ramtron’s VRS51L2070 microcontroller. |
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| F-RAM Automotive Information |
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F-RAM in Automotive Applications
05/01/2005
(80 KB)
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| This paper covers the use of F-RAM in many automotive applications, including airbag, telematics, entertainment, and control systems. |
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