STK15C88-NF25TR Cypress Semiconductor Corp, STK15C88-NF25TR Datasheet - Page 5

• Manufacturer Part Number: STK15C88-NF25TR
• Description: STK15C88-NF25TR
• Manufacturer: Cypress Semiconductor Corp

Specifications of STK15C88-NF25TR

• Format - Memory: RAM
• Memory Type: NVSRAM (Non-Volatile SRAM)
• Memory Size: 256K (32K x 8)
• Speed: 25ns
• Interface: Parallel
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-SOIC (7.5mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Hardware Protect
The STK15C88 offers hardware protection against inadvertent
STORE operation and SRAM WRITEs during low voltage condi-
tions. When V
operations and SRAM WRITEs are inhibited.
Noise Considerations
The STK15C88 is a high speed memory. It must have a high
frequency bypass capacitor of approximately 0.1 µF connected
between V
as possible. As with all high speed CMOS ICs, careful routing of
power, ground, and signals reduce circuit noise.
Low Average Active Power
CMOS technology provides the STK15C88 the benefit of
drawing significantly less current when it is cycled at times longer
than 50 ns.
I
consumption is shown for both CMOS and TTL input levels
(commercial temperature range, VCC = 5.5V, 100% duty cycle
on chip enable). Only standby current is drawn when the chip is
disabled. The overall average current drawn by the STK15C88
depends on the following items:
Figure 2. Current Versus Cycle Time (WRITE)
Document Number: 001-50593 Rev. *B
1. The duty cycle of chip enable
2. The overall cycle rate for accesses
3. The ratio of READs to WRITEs
4. CMOS versus TTL input levels
5. The operating temperature
6. The V
7. I/O loading
CC
and READ or WRITE cycle time. Worst case current
CC
CC
Figure 2
level
and V
CAP
<V
SS,
and
SWITCH
using leads and traces that are as short
Figure 3
, all externally initiated STORE
show the relationship between
Figure 3. Current Versus Cycle Time (READ)
Best Practices
nvSRAM products have been used effectively for over 15 years.
While ease-of-use is one of the product’s main system values,
experience gained working with hundreds of applications has
resulted in the following suggestions as best practices:
■
■
The nonvolatile cells in an nvSRAM are programmed on the
test floor during final test and quality assurance. Incoming
inspection routines at customer or contract manufacturer’s
sites, sometimes, reprogram these values. Final NV patterns
are typically repeating patterns of AA, 55, 00, FF, A5, or 5A.
End product’s firmware should not assume a NV array is in a
set programmed state. Routines that check memory content
values to determine first time system configuration and cold or
warm boot status should always program a unique NV pattern
(for example, complex 4-byte pattern of 46 E6 49 53 hex or
more random bytes) as part of the final system manufacturing
test to ensure these system routines work consistently.
Power up boot firmware routines should rewrite the nvSRAM
into the desired state. While the nvSRAM is shipped in a preset
state, best practice is to again rewrite the nvSRAM into the
desired state as a safeguard against events that might flip the
bit inadvertently (program bugs and incoming inspection
routines).
STK15C88
Page 5 of 16
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