STK14D88
NOISE CONSIDERATIONS
DATA PROTECTION
The STK14D88 is a high-speed memory and so
must have a high-frequency bypass capacitor of
The STK14D88 protects data from corruption during
low-voltage conditions by inhibiting all externally
initiated STORE and WRITE operations. The low-
approximately 0.1 μF connected between V
and
CC
V
, using leads and traces that are a short as pos-
volage condition is detected when V <V
.
SS
CC
SWITCH
sible. As with all high-speed CMOS ICs, careful rout-
ing of power, ground, and signals will reduce circuit
noise.
If the STK14D88 is in a WRITE mode (both E and W
low) at power-up, after a RECALL, or after a
STORE, the WRITE will be inhibited until a negative
transition on E or W is detected. This protects
against inadvertent writes during power up or brown
out conditions.
PREVENTING AUTOSTORE
The AutoStore function can be disabled by initiating
an AutoStore Disable sequence. A sequence of
READ operations is performed in a manner similar
to the software STORE initiation. To initiate the
AutoStore Disable sequence, the following
sequence of E controlled or G controlled READ
operations must be performed:
LOW AVERAGE ACTIVE POWER
CMOS technology provides the STK14D88 with the
benefit of power supply current that scales with
cycle time. Less current will be drawn as the mem-
ory cycle time becomes longer than 50 ns. Figure 4
1 Read Address 0x0E38 Valid READ
2 Read Address 0x31C7 Valid READ
3 Read Address 0x03E0 Valid READ
4 Read Address 0x3C1F Valid READ
5 Read Address 0x303F Valid READ
6 Read Address 0x03F8 AutoStore Disable
shows the relationship between I
WRITE cycle time. Worst-case current consumption
is shown for commercial temperature range,
and READ/
CC
V
=3.6V, and chip enable at maximum frequency.
CC
Only standby current is drawn when the chip is dis-
abled. The overall average current drawn by the
STK14D88 depends on the following items:
The AutoStore can be re-enabled by initiating an
AutoStore Enable sequence. A sequence of READ
operations is performed in a manner similar to the
software RECALL initiation. To initiate the AutoStore
Enable sequence, the following sequence of E con-
trolled or G controlled READ operations must be
performed:
1
2
3
4
5
6
The duty cycle of chip enable
The overall cycle rate for operations
The ratio of READs to WRITEs
The operating temperature
The VCC Level
I/O Loading
1 Read Address 0x0E38 Valid READ
2 Read Address 0x31C7 Valid READ
3 Read Address 0x03E0 Valid READ
4 Read Address 0x3C1F Valid READ
5 Read Address 0x303F Valid READ
6 Read Address 0x07F0 AutoStore Enable
50
40
30
20
10
0
Writes
Reads
If the AutoStore function is disabled or re-enabled, a
manual STORE operation (Hardware or Software)
needs to be issued to save the AutoStore state
through subsequent power down cycles. The part
comes from the factory with AutoStore enabled.
50 100 150 200 300
Cycle Time (ns)
Figure 4 - Current vs. Cycle Time
Rev 1.7
Document Control #ML0033
February 2007
13
SIMTEK [ SIMTEK CORPORATION ]
