CAT24C44 Catalyst Semiconductor, CAT24C44 Datasheet - Page 7

• Manufacturer Part Number: CAT24C44
• Description: 256-Bit Serial Nonvolatile CMOS Static RAM
• Manufacturer: Catalyst Semiconductor

RCL/RECALL
Data is transferred from the E
RAM by either sending the RCL instruction or by pulling
the RECALL input pin low. A recall operation must be
performed before the E
operations can be executed. Either a hardware or soft-
ware recall operation will set the “previous recall” latch
internal to the CAT24C44.
POWER-ON RECALL
The CAT24C44 has a power-on recall function that
transfers the E
all functions are inhibited for at least 200ns (T
stable V
STO/STORE
Data in the RAM memory area is stored in the E
memory either by sending the STO instruction or by
pulling the STORE input pin low. As security against any
Figure 5. Recall Cycle Timing
Figure 6. Hardware Store Cycle Timing
RECALL
RECALL
RECALL
RECALL
STORE
STORE
STORE
STORE
cc
RECALL
.
STORE
DO
2
PROM data to the RAM. After Power-up,
DO
2
PROM store, or RAM write
2
PROM data memory to
t RCZ
pur
2
PROM
) from
t STZ
t RCP
7
HIGH-Z
inadvertent store operations, the following conditions
must each be met before data can be transferred into
nonvolatile storage:
• The “previous recall” latch must be set (either a
• The “write enable” latch must be set (WREN
• STO instruction issued or STORE input low.
During the store operation, all other CAT24C44 func-
tions are inhibited. Upon completion of the store opera-
tion, the “write enable” latch is reset. The device also
provides false store protection whenever V
a 3.5V level. If V
operation is disabled and the “write enable” latch is
reset.
t STP
software or hardware recall operation).
instruction issued).
t RCC
HIGH-Z
t ST
t ORC
CC
falls below this level, the store
t ARC
UNDEFINED DATA
VALID DATA
Doc. No. 25019-0A 2/98 N-1
CC
falls below
5157 FHD F06
5157 FHD F07