AN92577 Migrating from FM25H20 to FM25V20A Author: Girija V Chougala Associated Part Family: FM25H20, FM25V20A Related Application Notes: For a complete list, click here. AN92577 compares the key features of the FM25H20 and FM25V20A devices. FM25H20 is now obsolete. This application note explains how FM25V20A is a replacement for FM25H20. 1 Introduction The FM25V20A, a 2-Mb Serial (SPI) F-RAM™, is a replacement device for FM25H20, which is now obsolete. For most designs, the FM25V20A device can be considered a superset of the FM25H20. The two devices are identical in terms of pinout, package composition and dimensions, and read/write functionality. This application note compares the key features of the two devices and shows how FM25V20A is a replacement for FM25H20. 2 Device Compatibility From a software point of view, the two devices are identical. From a hardware point of view, they are identical for the SOIC package, but the DFN package requires a change in the PCB assembly process. In both the FM25H20 and FM25V20A, the EXPOSED PAD of the DFN package is not connected to the die and must be left floating (in other words, no connect in the schematic design). Also, in FM25V20A, the EXPOSED PAD must not be soldered on the PCB. FM25H20 does not share this restriction. Refer to Critical Considerations for more details on the DFN package assembly requirement. The FM25V20A provides a lower active current and standby current and adds features such as operation down to 2.0 V and Device ID. Table 1 shows a compatibility chart for FM25H20 and FM25V20A. For a detailed comparison, see Table 3. Table 1. Compatibility Chart FM25H20 Feature or Spec Is FM25V20A compatible? Package Yes Pinout Yes Package Footprint 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 * Packages are footprint compatible but DFN package requires change in the PCB assembly process. Refer to Critical Considerations for more details. www.cypress.com Document No. 001-92577 Rev. *A 1 Migrating from FM25H20 to FM25V20A 3 Ordering Part Numbers Table 2 gives the recommended FM25V20A ordering part numbers that correspond to the FM25H20 ordering part numbers. Table 2. Recommended Ordering Part Numbers for Migration FM25H20 Ordering Part Number FM25V20A Status Ordering Part Number FM25H20-G FM25V20A-G FM25H20-GTR FM25H20-DG FM25V20A-GTR Obsolete FM25H20-DGTR 4 Production FM25V20A-DG Comments Status FM25V20A-DGTR Hardware change not required. System firmware update is required if you wish to use the additional Device ID feature supported in FM25V20A. Hardware change is required in the PCB assembly process. System firmware update is required if you wish to use the additional Device ID feature supported in FM25V20A. Detailed Comparison of FM25H20 and FM25V20A Table 3 gives a detailed comparison of the two devices. Table 3. Detailed Comparison Features or Specs Package Types Pinout/Package Outlines Package Footprint Temperature Range Operating Voltage Range Active Supply Current Standby Current Sleep Mode Current Output LOW Voltage (VOL) Read/Write Function Clock Frequency Data Retention FM25H20 FM25V20A Comments -G, -DG -G, -DG SOIC-8, DFN-8 SOIC-8, DFN-8 SOIC-8 SOIC-8 Identical DFN-8 DFN-8 The EXPOSED PAD in FM25V20A must not be soldered on the PCB. Refer to DFN Package Assembly Requirement for more details. –40 ºC to +85 ºC –40 ºC to +85 ºC 2.7 V to 3.6 V 2.0 V to 3.6 V Identical “Green” (RoHS) packages Identical DFN and wide SOIC (208 mils) packages Identical FM25V20A has a low-voltage operation. 1.0 mA @ 1 MHz 300 µA @ 1 MHz 10.0 mA @ 40 MHz 3.0 mA @ 40 MHz 270 µA @ 85 ºC 250 µA @ 85 ºC 8 µA 8 µA 0.4 V @ IOL = 1.6 mA 0.4 V @ IOL = 2 mA FM25V20 has better output LOW specification. – – Identical 2-byte addressing, identical opcodes 40 MHz 40 MHz 10 years (+85 ºC) 10 years (+85 ºC) FM25V20A offers lower active current. FM25V20A has lower standby current. Identical Identical 38 years (+75 ºC) 38 years (+75 ºC) 151 years (+65 ºC) 151 years (+65 ºC) Endurance (Write/Read Cycles) 1E+14 1E+14 Identical VDD Power-Up Ramp Rate (tVR) 50 µs/V 50 µs/V Identical VDD Power-Down Ramp Rate (tVF) 100 µs/V 100 µs/V Identical 1 ms 1 ms Identical – Yes Additional feature in FM25V20A Power Up to First Access (tPU) Device ID Feature www.cypress.com Document No. 001-92577 Rev. *A Identical 2 Migrating from FM25H20 to FM25V20A 4.1 Device ID Feature The FM25V20A supports an additional feature. It incorporates a 9-byte read-only Device ID (7F7F7F7F7F7FC22508h) to identify the product uniquely. The Device ID allows the host to determine the manufacturer, product density, and product revision. A system firmware update is required to use this feature in FM25V20A. For more details, review the FM25V20A datasheet. 5 Critical Considerations You should consider all the parameter differences specified in Table 3 during the migration to FM25V20A. This section discusses the critical differences. Also review the datasheet when migrating to the new part. 5.1 DFN Package Assembly Requirement The EXPOSED PAD in FM25V20A shown in the Figure 1 must not be soldered on the PCB. Soldering the EXPOSED PAD will cause the die to be exposed to excessive heat, which can result in bit failures and margin loss. Therefore, ensure that the EXPOSED PAD of the DFN package is masked on the PCB during the soldering process of the FM25V20A device. There are two ways of masking the EXPOSED PAD, which is explained below: 1. Mask the Stencil opening for the EXPOSED PAD during stencil creation which can be done without updating the existing board layout design. 2. Mask the EXPOSED PAD in the solder paste film of the PCB design layout if you are designing a new board layout. Figure 1. 8-Pin DFN Package Outline EXPOSED PAD www.cypress.com Document No. 001-92577 Rev. *A 3 Migrating from FM25H20 to FM25V20A 6 Summary This application note compared the key features of the FM25H20 and FM25V20A in detail and explained how FM25V20A is a replacement for FM25H20. 7 Related Documents 7.1 Datasheets 7.2 FM25H20: 2-Mbit (256 K × 8) Serial (SPI) F-RAM datasheet FM25V20A: 2-Mbit (256 K × 8) Serial (SPI) F-RAM datasheet Application Note AN304 – SPI Guide for F-RAM www.cypress.com Document No. 001-92577 Rev. *A 4 Migrating from FM25H20 to FM25V20A Document History Document Title: AN92577 - Migrating from FM25H20 to FM25V20A Document Number: 001-92577 Revision ** ECN 4481550 Orig. of Change GVCH Submission Date 08/22/2014 Description of Change New Application Note FM25H20 part status changed from “Not Recommended For New Designs” to “Obsolete”. *A 4812765 GVCH 06/26/2015 FM25V20A part status changed from “Sample” to “In-Production”. Updated Device Compatibility. Updated Table 1 through Table 3 for DFN package compatibility. Added Critical Considerations. www.cypress.com Document No. 001-92577 Rev. *A 5 Migrating from FM25H20 to FM25V20A 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. 001-92577 Rev. *A 6