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 EWENinstruction is executed, program-
ming remains enabled until an EWDS instruction is
executed or VCC is removed from the device.
To protect against accidental data disturbance, the
EWDSinstruction 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 EWENand EWDSinstructions.
FIGURE 3-5:
EWDS TIMING
TCSL
CS
CLK
•••
1
0
0
0
0
x
x
DI
FIGURE 3-6:
EWEN TIMING
TCSL
CS
CLK
•••
1
0
0
1
1
x
x
DI
© 2007 Microchip Technology Inc.
DS21929D-page 13
MICROCHIP [ MICROCHIP ]
