CAT93C46 Datasheet, PDF (6/9 Pages) Catalyst Semiconductor – 1K/2K/2K/4K/16K-Bit Microwire Serial E2PROM

93C46/56/57/66/86
The format for all instructions sent to the device is a
logical "1" start bit, a 2-bit (or 4-bit) opcode, 6-bit (93C46)/
/7-bit (93C57)/ 8-bit (93C56 or 93C66)/10-bit (93C86)
(an additional bit when organized X8) and for write
operations a 16-bit data field (8-bit for X8 organizations).
Note: This note is applicable only to 93C86. The Write,
Erase, Write all and Erase all instructions require PE=1.
If PE is left floating, 93C86 is in Program Enabled mode.
For Write Enable and Write Disable instruction PE=don’t
care.
Read
Upon receiving a READ command and an address
(clocked into the DI pin), the DO pin of the CAT93C46/
56/57/66/86 will come out of the high impedance state
and, after sending an initial dummy zero bit, will begin
shifting out the data addressed (MSB first). The output
data bits will toggle on the rising edge of the SK clock and
are stable after the specified time delay (t_PD0 or t_PD1)
For the 93C56/57/66/86, after the initial data word has
been shifted out and CS remains asserted with the SK
clock continuing to toggle, the device will automatically
increment to the next address and shift out the next data
word in a sequential READ mode. As long as CS is
continuously asserted and SK continues to toggle, the
device will keep incrementing to the next address auto-
matically until it reaches to the end of the address space,
then loops back to address 0. In the sequential READ
mode, only the initial data word is preceeded by a
dummy zero bit. All subsequent data words will follow
without a dummy zero bit.
Write
After receiving a WRITE command, address and the
data, the CS (Chip Select) pin must be deselected for a
minimum of tCSMIN. The falling edge of CS will start the
self clocking clear and data store cycle of the memory
location specified in the instruction. The clocking of the
SK pin is not necessary after the device has entered the
self clocking mode. The ready/busy status of the
CAT93C46/56/57/66/86 can be determined by selecting
the device and polling the DO pin. Since this device
features Auto-Clear before write, it is NOT necessary to
erase a memory location before it is written into.
Figure 2b. Read Instruction Timing (93C56/57/66/86)
SK
1
11
1
111
11
1
1
1
1
1
1
CS
AN AN–1
A0
DI
11
0
Don't Care
HIGH-Z
DO
Dummy 0
D15 _{. . .} D0
or
D7 _{. . .} D0
Address + 1
D15 _{. . .} D0
or
D7 _{. . .} D0
Address + 2
D15 _{. . .} D0
or
D7 _{. . .} D0
Address + n
D15 _{. . .}
or
D7 _{. . .}
Figure 3. Write Instruction Timing
SK
CS
AN AN-1
DI
101
A0 DN
HIGH-Z
DO
Doc. No. 25056-00 2/98 M-1
6
tCS
STATUS
VERIFY
D0
STANDBY
tSV
BUSY
READY
tEW
tHZ
HIGH-Z
93C46/56/57/66/86 F05