
8
CAT64LC10/20/40
Doc. No. 1021, Rev. A
WRITE cycle. The RDY/
BSY
 pin will output the 
BUSY
status (LOW) one t
SV
 after the rising edge of the 32nd
clock (the last data bit) and will stay LOW until the write
cycle is complete. Then it will output a logical “1” until the
next WRITE cycle. The RDY/
BSY
 output is not affected
by the input of 
CS
.
An alternative to get RDY/
BSY
 status is from the DO pin.
During a write cycle, asserting a LOW input to the 
CS
 pin
will cause the DO pin to output the RDY/
BSY
 status.
Bringing 
CS
 HIGH will bring the DO pin back to a high
impedance state again. After the device has completed
a WRITE cycle, the DO pin will output a logical “1” when
the device is deselected. The rising edge of the first “1”
input on the DI pin will reset DO back to the high
impedance state again.
The WRITE operation can be halted anywhere in the
operation by the RESET input. If a RESET pulse occurs
during a WRITE operation, the device will abort the
operation and output a READY status.
NOTE: Data may be corrupted if a RESET occurs while
the device is 
BUSY
. If the reset occurs before the 
BUSY
period, no writing will be initiated. However, if RESET
occurs after the 
BUSY
 period, new data will have been
written over the old data.
Figure 6.  RESET During 
BUSY
 Instruction Timing
Figure 7.  EWEN Instruction Timing
5064 FHD F09
* Please check instruction set table for address
SK
DI
CS
DO
RESET
1
0
1
0
0
1
0
0
ADDRESS*
D15
D0
tWR
RDY/
BUSY
SK
DI
CS
DO
RESET
1
0
1
0
0
0
1
1
HIGH-Z
HIGH
RDY/
BUSY