AN325 Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B.pdf

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
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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
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Migrating from Grade 1 version of FM25640 to Grade 1 version of FM25640B
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