CAT24C44

7

Doc. No. MD-1083, Rev. T

© 2008 SCILLC. All rights reserved.

Characteristics subject to change without notice

RCL/

RECALL

RECALL

RECALL

RECALL

RECALL

Data is transferred from the EEPROM data memory to

RAM by either sending the RCL instruction or by pulling

the

RECALL input pin low. A recall operation must be

performed before the EEPROM store, or RAM write

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 EEPROM data to the RAM. After Power-

STO/

STORE

STORE

STORE

STORE

STORE

Data in the RAM memory area is stored in the EEPROM

memory either by sending the STO instruction or by

pulling the

STORE input pin low. As security against any

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

software or hardware recall operation).

• The “write enable” latch must be set (WREN

instruction issued).

• 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

operation is disabled and the “write enable” latch is

reset.

Figure 6. Hardware Store Cycle Timing

Figure 5. Recall Cycle Timing

RECALL

tRCZ

tORC

tRCC

tRCP

tARC

VALID DATA

UNDEFINED DATA

DO

HIGH-Z

STORE

tST

tSTP

DO

tSTZ

HIGH-Z