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93LC56AB Datasheet, PDF (6/12 Pages) Microchip Technology – 2K 2.5V Microwave Serial EEPROM | |||
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93LC56A/B
3.6 ERASE/WRITE Disable and Enable
(EWDS/EWEN)
The 93LC56A/B powers up in the ERASE/WRITE
Disable (EWDS) state. All programming modes must
be preceded by an ERASE/WRITE Enable (EWEN)
instruction. Once the EWEN instruction is executed,
programming remains enabled until an EWDS instruc-
tion is executed or VCC is removed from the device. To
protect against accidental data disturbance, the EWDS
instruction can be used to disable all ERASE/WRITE
functions and should follow all programming opera-
tions. Execution of a READ instruction is independent
of both the EWDS and EWEN instructions.
FIGURE 3-4: EWDS TIMING
CS
CLK
3.7 READ
The READ instruction outputs the serial data of the
addressed memory location on the DO pin. A dummy
zero bit precedes the 8-bit (93LC56A) or 16-bit
(93LC56B) output string. The output data bits will toggle
on the rising edge of the CLK and are stable after the
speciï¬ed time delay (TPD). Sequential read is possible
when CS is held high. The memory data will automati-
cally cycle to the next register and output sequentially.
TCSL
DI
1
0
0
0
0
X
â¢â¢â¢
X
FIGURE 3-5: EWEN TIMING
TCSL
CS
CLK
DI
1
0
0
1
1
X
â¢â¢â¢
X
FIGURE 3-6: READ TIMING
CS
CLK
DI
DO
1
1 0 An â¢â¢â¢ A0
HIGH-Z
0 Dx â¢â¢â¢ D0 Dx â¢â¢â¢ D0 Dx â¢â¢â¢ D0
DS21208A-page 6
Preliminary
© 1997 Microchip Technology Inc.
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