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2005 Microchip Technology Inc.
DS21929A-page 13
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) instruction.
Once the EWEN instruction is executed, programming
remains enabled until an EWDS instruction 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
operations.
Execution
of
a
READ
instruction
is
independent of both the EWEN and EWDS instructions.
FIGURE 3-5:
EWDS TIMING
FIGURE 3-6:
EWEN TIMING
CS
CLK
DI
10
00
0
X
X
TCSL
1
X
CS
CLK
DI
00
1
X
TCSL