CAT93C56LI-G Datasheet, PDF (7/17 Pages) ON Semiconductor – 2-Kb Microwire Serial CMOS EEPROM

CAT93C56, CAT93C57
Read
Upon receiving a READ command and an address
(clocked into the DI pin), the DO pin of the CAT93C56/57
will come out of the high impedance state and, after sending
an initial dummy zero bit, will begin shifting out the data
addressed (MSB first). The output data bits will toggle on
the rising edge of the SK clock and are stable after the
specified time delay (t_PD0 or t_PD1).
For the CAT93C56/57, after the initial data word has been
shifted out and CS remains asserted with the SK clock
continuing to toggle, the device will automatically
increment to the next address and shift out the next data word
in a sequential READ mode. As long as CS is continuously
asserted and SK continues to toggle, the device will keep
incrementing to the next address automatically until it
reaches to the end of the address space, then loops back to
address 0. In the sequential READ mode, only the initial
data word is preceeded by a dummy zero bit. All subsequent
data words will follow without a dummy zero bit. The
READ instruction timing is illustrated in Figure 3.
Erase/Write Enable and Disable
The CAT93C56/57 powers up in the write disable state.
Any writing after power−up or after an EWDS (erase/write
disable) instruction must first be preceded by the EWEN
(erase/write enable) instruction. Once the write instruction
is enabled, it will remain enabled until power to the device
is removed, or the EWDS instruction is sent. The EWDS
instruction can be used to disable all CAT93C56/57 write
and erase instructions, and will prevent any accidental
writing or clearing of the device. Data can be read normally
from the device regardless of the write enable/disable status.
The EWEN and EWDS instructions timing is shown in
Figure 4.
SK
CS
A_N A_N−1
A₀
DI
11
0
t_PD0
HIGH−Z
DO
Don’t Care
Dummy 0
D₁₅ . . . D₀
or
D₇ . . . D₀
Address + 1
D₁₅ . . . D₀
or
D₇ . . . D₀
Figure 3. READ Instruction Timing
Address + 2
D₁₅ . . . D₀
or
D₇ . . . D₀
Address + n
D₁₅ . . .
or
D₇ . . .
SK
CS
STANDBY
DI
1 00
*
* ENABLE = 11
DISABLE = 00
Figure 4. EWEN/EWDS Instruction Timing
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