5

CAT25C01/02/04/08/16

Doc. No. 25067-00 5/00

Advanced Information

Status Register Bits

Array Address

Protection

BP1

BP0

Protected

0

0

None

No Protection

0

1

25C01: 60-7F

Quarter Array Protection

25C02: C0-FF

25C04: 180-1FF

25C08: 0300-03FF

25C16: 0600-07FF

1

0

25C01: 40-7F

Half Array Protection

25C02: 80-FF

25C04: 100-1FF

25C08: 0200-03FF

25C16: 0400-07FF

1

1

25C01: 00-7F

Full Array Protection

25C02: 00-FF

25C04: 000-1FF

25C08: 0000-03FF

25C16: 0000-07FF

BLOCK PROTECTION BITS

76543210

WPEN

PR_MODE

SPI_MODE

X

BP1

BP0

WEL

RDY

STATUS REGISTER

HOLD

HOLD

HOLD

HOLD

HOLD: Hold

HOLD is the HOLD pin. The HOLD pin is used to pause

transmission to the CAT25C01/02/04/08/16 while in the

middle of a serial sequence without having to re-transmit

entire sequence at a later time. To pause,

HOLD must be

brought low while SCK is low. The SO pin is in a high

impedance state during the time the part is paused, and

transitions on the SI pins will be ignored. To resume

communication,

HOLD is brought high, while SCK is low.

(

HOLD should be held high any time this function is not

being used.)

timing sequence.

STATUS REGISTER

The Status Register indicates the status of the device.

The

RDY (Ready) bit indicates whether the CAT25C01/

02/04/08/16 is busy with a write operation. When set to

1 a write cycle is in progress and when set to 0 the device

indicates it is ready. This bit is read onlyThe WEL (Write

Enable) bit indicates the status of the write enable latch.

When set to 1, the device is in a Write Enable state and

when set to 0 the device is in a Write Disable state. The

WEL bit can only be set by the WREN instruction and can

be reset by the WRDI instruction.

Protected

Unprotected

Status

WPEN

WP

WP

WP

WP

WP

WEL

Blocks

Blocks

Register

0

X

0

Protected

Protected

Protected

0

X

1

Protected

Writable

Writable

1

Low

0

Protected

Protected

Protected

1

Low

1

Protected

Writable

Protected

X

High

0

Protected

Protected

Protected

X

High

1

Protected

Writable

Writable

WRITE PROTECT ENABLE OPERATION