Cypress Perform STK14D88 - Manual (Page 13)

STK14D88
Document Number: 001-52037 Rev. ** Page 13 of 17
Figure 13. Current versus Cycle Time
Noise Considerations
The STK14D88 is a high-speed memory and so must have a
high-frequency bypass capacitor of 0.1 µF connected between
both V
CC
pins and V
SS
ground plane with no plane break to chip
V
SS
. Use leads and traces that are as short as possible. As with
all high-speed CMOS ICs, careful routing of power, ground, and
signals will reduce circuit noise.
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 initi-
ation. To initiate the AutoStore Disable sequence, the following
sequence of E controlled or G controlled READ operations must
be performed:
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
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
controlled or G controlled READ operations must be performed:
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
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.
In all cases, make sure the READ sequence is uninterrupted. For
example, an interrupt that occurs in the sequence that reads the
nvSRAM would abort this sequence, resulting in an error.
A
v
er
age
Act
iv
e
C
u
rrent
(mA)
100 150 200 300
0
10
20
30
40
50
Writes
Reads
Cycle Time (ns)
50
[+] Feedback