93AA56CT-ESLASHMS datasheet(9/28 Pages) MICROCHIP

9 / 28 page

DS21794E-page 9

93AA56A/B/C, 93LC56A/B/C, 93C56A/B/C

2.6

Erase/Write Disable and Enable

(EWDS/EWEN)

The 93XX56A/B/C 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 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 opera-

tions. Execution of a READ instruction is independent of

both the EWEN and EWDS instructions.

FIGURE 2-5:

EWDS TIMING

FIGURE 2-6:

EWEN TIMING

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. The output data bits will toggle on

the rising edge of the CLK and are stable after the spec-

ified 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.

FIGURE 2-7:

READ TIMING

CLK

•••

TCSL

CLK

TCSL

•••

CLK

•••

High-Z

•••

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