
STK16C88-3
March 2006
7
Document Control # ML0019 rev 0.2
The 
AutoStorePlus
 STK16C88-3 is a fast 32K x 8 
SRAM that does not lose its data on power-down. 
The data is preserved in integral 
QuantumTrap
Nonvolatile Elements while power is unavailable. 
The nonvolatility of the STK16C88-3 does not 
require any system intervention or support: 
AutoStorePlus
 on power-down and automatic 
RECALL on power-up guarantee data integrity with-
out the use of batteries.
NOISE CONSIDERATIONS
Note that the STK16C88-3 is a high-speed memory 
and so must have a high-frequency bypass capaci-
tor of approximately 0.1
μ
F connected between V
CC
and V
SS
, using leads and traces that are as short as 
possible. As with all high-speed 
CMOS
 ICs, normal 
careful routing of power, ground and signals will 
help prevent noise problems.
SRAM READ
The STK16C88-3 performs a 
READ
 cycle whenever 
E and G are low and W is high. The address speci-
fied on pins A
0-14
determines which of the 32,768
data bytes will be accessed. When the 
READ
 is initi-
ated by an address transition, the outputs will be 
valid after a delay of t
AVQV
 (
READ
 cycle #1). If the 
READ
 is initiated by E or G, the outputs will be valid 
at t
ELQV
 or at t
GLQV
, whichever is later (
READ 
cycle #2). 
The data outputs will repeatedly respond to address 
changes within the t
AVQV
 access time without the need 
for transitions on any control input pins, and will 
remain valid until another address change or until E
or G is brought high.
SRAM WRITE
A 
WRITE
 cycle is performed whenever E and W are 
low. The address inputs must be stable prior to 
entering the 
WRITE
 cycle and must remain stable 
until either E or W goes high at the end of the cycle. 
The data on the common I/O pins DQ
0-7
 will be writ-
ten into the memory if it is valid t
DVWH
before the end 
of a W controlled 
WRITE
 or t
DVEH
before the end of an 
E controlled 
WRITE
. 
It is recommended that G be kept high during the 
entire 
WRITE
 cycle to avoid data bus contention on 
the common I/O lines. If G is left low, internal circuitry 
will turn off the output buffers t
WLQZ
 after W goes low.
AutoStorePlus
OPERATION 
The STK16C88-3’s automatic 
STORE
 on power-
down is completely transparent to the system. The 
AutoStore
 initiation takes less than 500ns when 
power is lost (V
CC
 < V
SWITCH
) at which point the part 
depends only on its internal capacitor for 
STORE
completion. If the power supply drops faster than 
20
μ
s/volt before Vccx reaches Vswitch, then a 2.2 
ohm resistor should be inserted between Vccx and 
the system supply to avoid a momentary excess of 
current between Vccx and Vcap.
In order to prevent unneeded 
STORE
 operations, 
automatic 
STORE
s 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
CC
 < V
RESET
), an internal 
RECALL
 request will be 
latched. When V
CC
 once again exceeds the sense 
voltage of V
SWITCH
, a 
RECALL
 cycle will automatically 
be initiated and will take t
RESTORE
 to complete.
If the STK16C88-3 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
Ω
 resistor should 
be connected either between W and system V
CC
 or 
between E and system V
CC
.
SOFTWARE NONVOLATILE 
STORE
The STK16C88-3 software 
STORE
 cycle is initiated 
by executing sequential 
READ
 cycles from six spe-
cific address locations. During the 
STORE
 cycle an 
erase of the previous nonvolatile data is first per-
formed, followed by a program of the nonvolatile 
elements. The program operation copies the 
SRAM
data into nonvolatile memory. Once a 
STORE
 cycle 
is initiated, further input and output are disabled until 
the cycle is completed.
Because a sequence of 
READ
s 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.
DEVICE OPERATION