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STK15C88-3P35 参数 Datasheet PDF下载

STK15C88-3P35图片预览
型号: STK15C88-3P35
PDF下载: 下载PDF文件 查看货源
内容描述: [Non-Volatile SRAM, 32KX8, 35ns, CMOS, PDIP28, 0.300 INCH, PLASTIC, DIP-28]
分类和应用: 静态存储器光电二极管内存集成电路
文件页数/大小: 10 页 / 291 K
品牌: SIMTEK [ SIMTEK CORPORATION ]
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STK15C88-3  
Internally, RECALL is a two-step procedure. First,  
the SRAM data is cleared, and second, the nonvola-  
tile information is transferred into the SRAM cells.  
After the tRECALL cycle time the SRAM will once again  
be ready for READ and WRITE operations. The  
RECALL operation in no way alters the data in the  
EEPROM cells. The nonvolatile data can be recalled  
an unlimited number of times.  
If the STK15C88-3 is in a WRITE state at the end of  
power-up RECALL, the SRAM data will be corrupted.  
To help avoid this situation, a 10K Ohm resistor  
should be connected either between W and system  
VCC or between E and system VCC.  
HARDWARE PROTECT  
The STK15C88-3 offers hardware protection  
against inadvertent STORE operation and SRAM  
AutoStoreTM OPERATION  
WRITEs during low-voltage conditions. When VCC  
<
The STK15C88-3 uses the intrinsic system capaci-  
tance to perform an automatic STORE on power  
down. As long as the system power supply takes at  
least tSTORE to decay from VSWITCH down to 2.6V, the  
STK15C88-3 will safely and automatically store the  
SRAM data in EEPROM on power down.  
VSWITCH, all software STORE operations and SRAM  
WRITEs are inhibited.  
LOW AVERAGE ACTIVE POWER  
The STK15C88-3 draws significantly less current  
when it is cycled at times longer than 50ns. Figure 2  
shows the relationship between ICC and READ cycle  
time. Worst-case current consumption is shown for  
both CMOS and TTL input levels (commercial tem-  
perature range, VCC = 3.6V, 100% duty cycle on chip  
enable). Figure 3 shows the same relationship for  
WRITE cycles. If the chip enable duty cycle is less  
than 100%, only standby current is drawn when the  
chip is disabled. The overall average current drawn  
by the STK15C88-3 depends on the following  
items: 1) CMOS vs. TTL input levels; 2) the duty  
cycle of chip enable; 3) the overall cycle rate for  
accesses; 4) the ratio of READs to WRITEs; 5) the  
operating temperature; 6) the VCC level; and 7) I/O  
loading.  
In order to prevent unneeded STORE operations,  
automatic STOREs will be ignored unless at least  
one WRITE operation has taken place since the  
most recent STORE or RECALL cycle. Software-  
initiated STORE cycles are performed regardless of  
whether a WRITE operation has taken place.  
POWER-UP RECALL  
During power up, or after any low-power condition  
(VCC < VRESET), an internal RECALL request will be  
latched. When VCC once again exceeds the sense  
voltage of VSWITCH, a RECALL cycle will automatically  
be initiated and will take tRESTORE to complete.  
50  
40  
30  
20  
50  
40  
30  
TTL  
CMOS  
20  
TTL  
10  
10  
CMOS  
0
0
50  
100  
150  
200  
50  
100  
150  
200  
Cycle Time (ns)  
Cycle Time (ns)  
Figure 2: ICC (max) Reads  
Figure 3: ICC (max) Writes  
September 2002  
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