93XX46X/56X/66X/76X/86X
3.6
ERASE/WRITE DISABLE And
ENABLE (EWDS/EWEN)
The 93XX series devices power-up in the Erase/Write
Disable (EWDS) state. All programming modes must
be preceded by an Erase/Write Enable (EWEN) instruc-
tion. Once the
EWEN
instruction is executed, program-
ming remains enabled until an
EWDS
instruction is
executed or V
CC
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
operations. Execution of a
READ
instruction is
independent of both the
EWEN
and
EWDS
instructions.
FIGURE 3-5:
EWDS TIMING
T
CSL
CS
CLK
DI
1
0
0
0
0
x
•••
x
FIGURE 3-6:
EWEN TIMING
T
CSL
CS
CLK
DI
1
0
0
1
1
x
•••
x
©
2007 Microchip Technology Inc.
DS21929D-page 13
MICROCHIP [ MICROCHIP TECHNOLOGY ]
