93AA86A Datasheet, PDF (9/28 Pages) Microchip Technology – 16K Microwire Compatible Serial EEPROM

93AA86A/B/C, 93LC86A/B/C, 93C86A/B/C
2.6 Erase/Write Disable and Enable
(EWDS/EWEN)
The 93XX86A/B/C powers up in the Erase/Write
Disable (EWDS) state. All programming modes must be
preceded by an Erase/Write Enable (EWEN) instruction.
FIGURE 2-3:
CS
EWDS TIMING
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.
TCSL
CLK
DI
1
00
00
x
•••
x
FIGURE 2-4:
EWEN TIMING
TCSL
CS
CLK
DI
1
00
1
1x
2.7 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 (If ORG pin is low or A-Version
devices) or 16-bit (If ORG pin is high or B-version
devices) output string.
FIGURE 2-5:
READ TIMING
CS
•••
x
The output data bits will toggle on the rising edge of the
CLK and are stable after the specified time delay (TPD).
Sequential read is possible when CS is held high. The
memory data will automatically cycle to the next register
and output sequentially.
CLK
DI
DO
1
1 0 An ••• A0
High-Z
0 Dx ••• D0 Dx ••• D0 Dx ••• D0
© 2005 Microchip Technology Inc.
DS21797G-page 9