AN319 Migrating from FM25CL64 to FM25CL64B Author: Girija Chougala Associated Project: No Associated Part Family: FM25CL64, FM25CL64B Software Version: None Related Documents: For a complete list, click here AN319 discusses the key differences that need to be considered when migrating from FM25CL64 to FM25CL64B. FM25CL64 is now obsolete and this application note explains how FM25CL64B is a replacement for FM25CL64. Table 1 shows the compatibility chart of FM25CL64 and FM25CL64B. For a detailed comparison, see Table 3. Introduction FM25CL64B, a 64-Kbit SPI F-RAM™, is a replacement device for FM25CL64, which is now obsolete. The two devices are identical in terms of pinout, packages, and read/write functionality. In terms of speed, both operate up to 20 MHz and have the same timing specifications. This application note discusses the key differences between the two devices that need to be considered when migrating from FM25CL64 to FM25CL64B. Table 1. Compatibility Chart FM25CL64 Feature or Spec Is FM25CL64B compatible? Package Yes Pinout Yes Temperature Range Yes Drop-In Replacement or Not? Operating Voltage Yes From a software point of view, the two devices are identical. The two devices are read/write compatible. Both devices use the same two-byte address. From a hardware point of view the key difference is the higher standby current of the FM25CL64B. Additionally, the FM25CL64B datasheet adds a power-up and power-down ramp rate specification of 30 µs / V and a power-up to first-access specification of 1 ms. Operating Current Yes Standby Current No Read / Write Function Yes Timing / Frequency Yes Data Retention Refer to Table 3 Endurance Yes Ordering Part Numbers Table 2 gives the recommended FM25CL64B ordering part numbers that correspond to the now obsolete FM25CL64 ordering part numbers. Table 2. Recommended Ordering Part Numbers for Migration FM25CL64 Ordering Part Number FM25CL64 -G FM25CL64B Status Obsolete Ordering Part Number FM25CL64B -G FM25CL64-GTR FM25CL64B -GTR FM25CL64-DG FM25CL64B -DG FM25CL64-DGTR FM25CL64B -DGTR www.cypress.com Comments Status In production Document No. 001-86842 Rev. *B No hardware or software change is required 1 Migrating from FM25CL64 to FM25CL64B Comparison of FM25CL64 and FM25CL64B 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 Standby Current Read / Write Function Clock Frequency FM25CL64 FM25CL64B Comments -G, -DG -G, -DG Identical “green” SOIC and TDFN packages SOIC-8, TDFN-8 SOIC-8, TDFN-8 - - Identical –40 ºC to +85 ºC –40 ºC to +85 ºC Identical 2.7 V to 3.65 V 2.7 V to 3.65 V Identical 350 µA @ 1 MHz 200 µA @ 1 MHz 7.0 mA @ 20 MHz 3.0 mA @ 20 MHz 1 µA 6 µA (max) 3 µA (typical) - - 20 MHz 20 MHz Identical outlines and board footprints FM25CL64B offers lower active current FM25CL64B has higher standby current Identical 2-byte addressing, Identical opcodes Identical 10 years (+85 ºC) Data Retention 45 years (+85 ºC) 38 years (+75 ºC) Data retention is lower 151 years (+65 ºC) Unlimited 1E+14 FM25CL64B’s endurance is large enough to be considered as unlimited for all practical applications. For a 64-byte loop, at 20 MHz, FM25CL64B’s endurance is 85 years. VDD Power-Up Ramp Rate (tVR) - 30 µs / V Power-up ramp rate should be slower than 30 µs / V for FM25CL64B VDD Power-Down Ramp Rate (tVF) - 30 µs / V Power-down ramp rate should be slower than 30 µs / V for FM25CL64B Power-Up to First Access (tPU) - 1 ms Endurance (Write/Read Cycles) After power-up, the first access FM25CL64B should be after 1 ms of Critical Considerations You should consider all the parameter differences mentioned in Table 3 during the migration to FM25CL64B. 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 FM25CL64B device. Ensure that the power-up and power-down ramp rates are slower than 30 µs / V in your system for proper operation of the device. Power-Up to First Access Power-up to first access specification is added in FM25CL64B device. Ensure that the FM25CL64B device is accessed only after 1 ms from power-up. Summary AN319 discussed the differences between FM25CL64 and FM25CL64B that need to be considered during migration to the FM25CL64B. www.cypress.com Document No. 001-86842 Rev. *B 2 Migrating from FM25CL64 to FM25CL64B Related Documents Datasheet FM25CL64B: 64-Kbit (8 K × 8) Serial (SPI) F-RAM datasheet Application Note AN304 – SPI GUIDE FOR F-RAM www.cypress.com Document No. 001-86842 Rev. *B 3 Migrating from FM25CL64 to FM25CL64B Document History Document Title: Migrating from FM25CL64 to FM25CL64B - AN319 Document Number: 001-86842 Revision ECN Orig. of Change Submission Date Description of Change ** 3944550 GVCH 03/26/2013 New Spec. *A 4279018 MEDU 03/05/2014 Updated to Cypress Template. Updated “VDD Power-Down Ramp Rate” for FM25CL64B from 100 µs / V to 30 µs / V. Updated “Power-Up to First Access” for FM25CL64B from 10 ms to 1 ms. *B 4498653 GVCH 09/22/2014 Changed title from “Differences between FM25CL64 and FM25CL64B” to “Migrating from FM25CL64 to FM25CL64B.” Updated abstract. Added “Ordering Part Numbers” section. Added title for Table 3. Added “Related Documents” section. www.cypress.com Document No. 001-86842 Rev. *B 4 Migrating from FM25CL64 to FM25CL64B 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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