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February, 2007

Document Control #ML0018 Rev 0.3

STK16C88

The AutoStore+ STK16C88 is a fast 32K x 8 SRAM

that does not lose its data on power-down. The data

is preserved in integral QuantumTrap non-volatile

storage elements when power is lost. Automatic

STORE on power-down and automatic RECALL on

power-up guarantee data integrity without the use of

batteries.

NOISE CONSIDERATIONS

Note that the STK16C88 is a high-speed memory

and so must have a high-frequency bypass capaci-

tor of approximately 0.1

μF connected between V

CC

and V

careful routing of power, ground and signals will help

prevent noise problems.

SRAM READ

and G are low and W is high. The address specified

on pins A

by an address transition, the outputs will be valid

after a delay of t

initiated by E or G, the outputs will be valid at t

at t

outputs will repeatedly respond to address changes

within the t

sitions on any control input pins, and will remain valid

until another address change or until E or G is

brought high.

SRAM WRITE

low. The address inputs must be stable prior to

until either E or W goes high at the end of the cycle.

The data on the common I/O pins DQ

ten into the memory if it is valid t

It is recommended that G be kept high during the

the common I/O lines. If G is left low, internal circuitry

will turn off the output buffers t

AutoStore+ OPERATION

The STK16C88’s automatic STORE on power-down

is completely transparent to the system. The

STORE initiation takes less than 500ns when power

is lost (V

only on its internal capacitor for STORE completion.

If the power supply drops faster than 20

μs/volt

before Vcc reaches Vswitch, then a 2.2 ohm resistor

should be inserted between Vcc and th system sup-

ply to avoid a momentary excess of current between

Vcc and internal capacitor.

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 or not a WRITE operation has taken place.

POWER-UP RECALL

During power up, or after any low-power condition

(V

latched. When V

voltage of V

be initiated and will take t

If the STK16C88 is in a WRITE state at the end of

power-up RECALL, the SRAM data will be cor-

rupted. To help avoid this situation, a 10k

Ω resistor

should be connected either between W and system

V

SOFTWARE NONVOLATILE STORE

The STK16C88 software STORE cycle is initiated

by executing sequential READ cycles from six spe-

cific address locations. During the STORE cycle,

previous non-volatile data is erased and then the

SRAM contents are written to the non-volatile stor-

age elements. Once a STORE cycle is initiated, fur-

ther inputs and outputs are disabled until the cycle is

completed.

Because a sequence of READs from specific

addresses is used for STORE initiation, it is impor-

tant that no other READ or WRITE accesses inter-

vene in the sequence or the sequence will be

aborted and no STORE or RECALL will take place.

To initiate the software STORE cycle, the following

READ

sequence must be performed:

nvSRAM OPERATION