AN325 Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B Author: Girija Chougala Associated Project: No Associated Part Family: FM25640-GA, FM25640B-GA Software Version: None Related Documents: For a complete list, click here AN325 discusses the key differences that need to be considered when migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B. FM25640 is now obsolete and this application note explains how FM25640B is a replacement for FM25640. Table 1. Compatibility Chart Introduction FM25640B-GA, a 64-Kbit SPI Grade 1 F-RAM™, is a replacement device for FM25640-GA, which is now obsolete. The two devices are identical in terms of package, pinout, DC / AC parameters, and read / write functionality. This application note discusses the key differences between the two devices that need to be considered when migrating from FM25640-GA to FM25640B-GA. FM25640-GA Feature or Spec Drop-In Replacement or Not? From a software point of view, the two devices are identical. Both the devices are read/write compatible and use the same two-byte address. From a hardware point of view, the key difference between the two devices is the FM25640B-GA’s lower operating current. Table 1 shows the compatibility chart of FM25640-GA and FM25640B-GA. For a detailed comparison, see Table 3. Is FM25640B-GA compatible? Package Yes Pinout Yes Temperature Range Yes Operating Voltage Yes Operating Current Yes Standby Current Yes Read / Write Function Yes Timing / Frequency Yes Data Retention Yes Endurance Yes Ordering Part Numbers Table 2 gives the recommended FM25640B-GA ordering part numbers that correspond to the now obsolete FM25640-GA ordering part numbers. Table 2. Recommended Ordering Part Numbers for Migration FM25640-GA Ordering Part Number FM25640-GA FM25640-GATR www.cypress.com FM25640B-GA Status Obsolete Ordering Part Number FM25640B-GA Comments Status In production FM25640B-GATR Document No. 001-86848 Rev. *B No hardware or software change is required 1 Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B Comparison of FM25640 and FM25640B Table 3 gives a detailed comparison of the two devices. Table 3. Detailed Comparison Package Types Package Outlines Pinout Temperature Range Operating Voltage Range Active Supply Current FM25640-GA FM25640B-GA Comments -GA -GA SOIC-8 SOIC-8 - - Identical –40 ºC to +125 ºC –40 ºC to +125 ºC Identical 4.5 V to 5.5 V 4.5 V to 5.5 V Identical 750 µA @ 1 MHz 300 µA @ 1 MHz 2.7 mA @ 4 MHz 1.2 mA @ 4 MHz Identical “green” SOIC package Identical outline and board footprint FM25640B-GA has lower operating current 10 µA (+85 ºC) 10 µA (+85 ºC) 30 µA (+125 ºC) 30 µA (+125 ºC) - - 4 MHz 4 MHz - - 9000 hours (+125 ºC) 11000 hours (+125 ºC) after 11 years (+105 ºC) 17 years (+55 ºC) 121 years (+85 ºC) 1E+12 1E+13 VDD Power-Up Ramp Rate (tVR) - 30 µs / V Power-up ramp rate should be slower than 30 µs / V for FM25640B-GA VDD Power-Down Ramp Rate (tVF) - 20 µs / V Power-down ramp rate should be slower than 20 µs / V for FM25640B-GA Power-Up to First Access (tPU) - 1 ms Standby Current Read / Write Function Clock Frequency AC Timing Parameters Data Retention Endurance (Write/Read Cycles) Identical Identical 2-byte addressing, Identical op-codes Identical All specification limits are the Identical FM25640B-GA offers better data retention FM25640B-GA offers improved endurance After power-up, the first access FM25640B-GA should be after 1 ms of Critical Considerations You should consider all the parameter differences mentioned in Table 3 during the migration to FM25640B-GA. This section discusses the critical differences. System designers should also review the datasheet when migrating to the new part. VDD Ramp Rate VDD power-up and power-down ramp rate specifications are added in FM25640B-GA device. Ensure that the power-up ramp rate is slower than 30 µs / V and power-down ramp rate is slower than 20 µs / V in your system. Power-Up to First Access Power-up to first access specification is added in FM25640B-GA device. Ensure that the FM25640B-GA device is accessed only after 1 ms from power-up. Summary AN325 discussed the differences between the Grade 1 versions of FM25640 and FM25640B that need to be considered during migration to the FM25640B. www.cypress.com Document No. 001-86848 Rev. *B 2 Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B Related Documents Datasheet FM25640B: 64-Kbit (8 K × 8) Serial (SPI) Automotive F-RAM datasheet Application Note AN304 – SPI GUIDE FOR F-RAM www.cypress.com Document No. 001-86848 Rev. *B 3 Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B Document History Document Title: Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B - AN325 Document Number: 001-86848 Revision ECN Orig. of Change Submission Date Description of Change ** 3944550 GVCH 03/26/2013 New Spec. *A 4279208 MEDU 03/05/2014 Updated to Cypress Template. Updated data retention for FM25640B-GA. Updated “VDD Power-Down Ramp Rate” for FM25640B-GA from 100 µs / V to 20 µs / V. Updated “Power-Up to First Access” for FM25640B-GA from 10 ms to 1 ms. *B 4498656 GVCH 09/23/2014 Changed title from “Differences between Grade 1 versions of FM25640 and FM25640B” to “Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B.” Updated abstract. Added “Ordering Part Numbers” section. Added title for Table 3. Added “Related Documents” section. www.cypress.com Document No. 001-86848 Rev. *B 4 Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B Worldwide Sales and Design Support Cypress maintains a worldwide network of offices, solution centers, manufacturer’s representatives, and distributors. To find the office closest to you, visit us at Cypress Locations. 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Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the right to make changes without further notice to the materials described herein. Cypress does not assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges. Use may be limited by and subject to the applicable Cypress software license agreement. www.cypress.com Document No. 001-86848 Rev. *B 5