STK11C88-S25 Cypress Semiconductor Corp, STK11C88-S25 Datasheet - Page 5

• Manufacturer Part Number: STK11C88-S25
• Manufacturer: Cypress Semiconductor Corp
• Type: NVSRAMr

Specifications of STK11C88-S25

• Word Size: 8b
• Organization: 32Kx8
• Density: 256Kb
• Interface Type: Parallel
• Access Time (max): 25ns
• Operating Supply Voltage (typ): 5V
• Package Type: SOIC
• Operating Temperature Classification: Commercial
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 4.5V
• Operating Temp Range: 0C to 70C
• Pin Count: 28
• Mounting: Surface Mount
• Supply Current: 97mA
• Lead Free Status / RoHS Status: Not Compliant

Hardware Protect
The STK11C88 offers hardware protection against inadvertent
STORE operation and SRAM WRITEs during low voltage condi-
tions. When V
tions and SRAM WRITEs are inhibited.
Noise Considerations
The STK11C88 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 help prevent noise problems.
Low Average Active Power
CMOS technology provides the STK11C88 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 percent duty
cycle on chip enable). Only standby current is drawn when the
chip is disabled. The overall average current drawn by the
STK11C88 depends on the following items:
Figure 2. Icc (max) Reads
Document Number: 001-50591 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
CC
and V
<V
SWITCH
SS,
and
using leads and traces that are as short
Figure 3
, all externally initiated STORE opera-
show the relationship between
Figure 3. Icc (max) Writes
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,
the experience gained working with hundreds of applications has
resulted in the following suggestions as best practices:
■
■
The nonvolatile cells in a 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.
The end product’s firmware should not assume that 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, a complex 4-byte pattern of 46 E6 49 53
hex or more random bytes) as part of the final system manufac-
turing 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 or incoming inspection
routines).
STK11C88
Page 5 of 16
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