Cypress AN20639 Installation and operating instructions

November 11, 2008 Document No. 001-20639 Rev. *C 1
Comparison between CY14B256L
and STK14C88-3 nvSRAM
Application Note Abstract
This application note compares the CY14B256L (0.25 μm) and the STK14C88-3 (0.8 μm) devices and presents the results.
Introduction
CY14B256L and STK14C88-3 are both 256K (32K x 8), 3V
nvSRAMs in two different technologies, 0.25 μm and 0.8 μm
respectively. These parts are functionally similar and can be
used in the same applications. However there are differences
in parameters, which should be considered when replacing
one part with the other.
The specifications in the data sheets of CY14B256L (0.25
μm) and STK14C88-3 (0.8 μm) are compared. Table 1 lists
the differences between these two devices. This comparison
is not intended to be comprehensive, because there are sub-
tle differences that are not relevant in most applications.
Most applications use autostore and autorecall features of
nvSRAM. To simplify the comparison, all electrical parame-
ters which may affect the application performance directly or
indirectly are considered. Designers must consider these dif-
ferences, and if necessary do appropriate changes in their
design.
Only those specifications that differ between CY14B256L
(0.25 μm) and STK14C88-3 (0.8 μm) nvSRAM are listed in
Table 1. These specifications may cause functional issues
when replacing one part with the other.
AN20639
Author: Shivendra Singh
Associated Project: No
Associated Part Family: CY14B256L and STK14C88-3
Associated Application Notes: None
Table 1. Comparison Table
Specification CY14B256L (35 nsec) STK14C88-3 (35 nsec)
Endurance 200,000 cycles 1,000,000 cycles
Retention 20 year 100 year
DC Electrical Characteristics
Vcc 2.7V min 3.6V max 3.0V min 3.6V max
Icc1 55 mA max 52 mA max
Icc3 10 mA max 9 mA max
Icc4 3 mA max 2 mA max
V
IH
2.0V min Vcc + 0.3V max 2.2V min Vcc + 0.5V max
Vcap
[1]
17 µF min 120 µF max 68 µF min 220 µF max
C
in
7 pF max 5 pF max
AC Switching Characteristics
t
OHA
3 ns min 5 ns min
t
LZCE
3 ns min 5 ns min
t
LZWE
3 ns min 5 ns min
Note
1. STK14C88-3 applications usually specify the use of 68 µF or 100 µF capacitors, which fall within the range of the CY14B256L device.
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November 11, 2008 Document No. 001-20639 Rev. *C 2
AN20639
Summary
In most applications you can directly substitute the CY14B256L for the STK14C88-3 nvSRAM.
Auto Store/Power Up Recall
tHRECALL [2]
20 ms max 550 µs max
tSTORE [3]
12.5 ms max 10 ms max
VSWITCH [4]
No minimum 2.65V max 2.7V min 2.95V max
Table 1. Comparison Table (continued)
Specification CY14B256L (35 nsec) STK14C88-3 (35 nsec)
Notes
2. The power up recall specification is the most dramatic difference between the two devices. To accommodate the much slower specification of the CY14B256L
device, system timing modifications may be required.
3. Store timing differences are not an issue because it occurs as a background operation when the system is powering down.
4. Even though there are small differences here they are unlikely to cause system level problems.
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AN20639
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November 11, 2008 Document No. 001-20639 Rev. *C 3
Document History Page
All trademarks or registered trademarks referenced herein are the property of their respective owners
Document Title: Comparison between CY14B256L and STK14C88-3 nvSRAM
Document Number: 001-20639
Revision ECN No. Orig. of Change Submission Date Description of Change
** 1410463 ZSK 08/23/07 New application note
*A 1639723 ZSK 10/16/07 Changed title
*B 1758963 ZSK 11/19/07 Minor change
*C 2610582 NXR 11/20/08 Changed title. Updated content to reflect change in part number
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