CAT35C704 Datasheet, PDF (8/14 Pages) Catalyst Semiconductor – 4K-Bit Secure Access Serial E2PROM

CAT35C704
Preliminary
DEVICE OPERATION
INSTRUCTIONS
The CAT35C704 instruction set includes 19 instruc-
tions.
Six instructions are related to security or write protec-
tion:
DISAC
ENAC
MACC
OVMPR
RMPR
WMPR
Disable Access
Enable Access
Modify Access Code
Override Memory Pointer Register
Read Memory Pointer Register
Write Memory Pointer Register
Six instructions are READ/WRITE/ERASE instructions:
ERAL
ERASE
READ
RSEQ
WRAL
WRITE
Clear All Locations
Clear Memory Locations
Read Memory
Read Sequentially
Write All
Write memory
Note: All write instructions will automatically perform a clear before
writing data.
Figure 9. EWEN/EWDS Timing
CS
Seven instructions are used as control and status func-
tions:
DISBSY
ENBSY
EWEN
EWDS
NOP
ORG
RSR
Disable Busy
Enable Busy
Program/Erase Enable
Program/Erase Disable
No Operations
Select Memory Organization
Read Status Register
UNPROTECTED MODE
As shipped from the factory, the CAT35C704 is in the
unprotected mode. The access code length is set to 0,
and the memory pointer is at address 00 hex. While in
this mode, any portion of the E²PROM array can be read
or written to without an access code. A portion of the
memory may be protected from any write or clear
operation by setting the memory pointer to the appropri-
ate address via the WMPR (Write Memory Pointer
Register) instruction:
WMPR [address]
CLK
DI
OP7
OP CODE
HIGH-Z
DO
Figure 10. Erase Timing
CS
CLK
DI
OP7
DO
OP CODE
HIGH-Z
Doc. No. 25045-00 2/98
OP0
5074 FHD F12
DON’T CARE
OP0
AN
A0
ADDRESS
tEW
tSV
READY
BUSY
8
5074 FHD F13