93c46b-st Microchip Technology Inc., 93c46b-st Datasheet - Page 9

• Manufacturer Part Number: 93c46b-st
• Description: 1k Microwire Compatible Serial Eeprom
• Manufacturer: Microchip Technology Inc.

2.6
The 93XX46A/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.
FIGURE 2-5:
FIGURE 2-6:
2.7
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 2-7:
© 2005 Microchip Technology Inc.
CLK
CLK
CS
DO
CS
DI
CLK
DI
CS
DI
Erase/Write Disable and Enable
(EWDS/EWEN)
Read
93AA46A/B/C, 93LC46A/B/C, 93C46A/B/C
High-Z
1
1
1
EWDS TIMING
EWEN TIMING
READ TIMING
1
0
0
0
0
0
An
0
1
•••
0
A0
1
0
Dx
x
x
•••
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.
The output data bits will toggle on the rising edge of the
CLK and are stable after the specified time delay (T
Sequential read is possible when CS is held high. The
memory data will automatically cycle to the next register
and output sequentially.
•••
•••
D0
Dx
x
x
•••
T
T
CSL
CSL
D0
Dx
•••
DS21749F-page 9
D0
PD
).