8

5242B–SEEPR–01/09

AT34C02C

PERMANENT SOFTWARE WRITE PROTECTION: The software write protection is enabled by

sending a command, similar to a normal write command, to the device which programs the per-

manent write protect register. This must be done with the WP pin low. The write protect register

is programmed by sending a write command with the device address of 0110 instead of 1010

with the address and data bit being don’t cares (see Figure 7 on page 8). Once the software

write protection has been enabled, the device will no longer acknowledge the 0110 control byte.

The software write protection cannot be reversed even if the device is powered down. The write

cycle time must be observed.

REVERSIBLE SOFTWARE WRITE PROTECTION: The reversible software write protection is

enabled by sending a command, similar to a normal write command, to the device which pro-

grams the reversible write protect register. This must be done with the WP pin low. The write

protect register is programmed by sending a write command 01100010 with pins A2 and A1 tied

to ground or don't connect and pin A0 connected to VHV (see Figure 8). The reversible write

protection can be reversed by sending a command 01100110 with pin A2 tied to ground or no

connect, pin A1 tied to VCC and pin A0 tied to VHV (see Figure 9).

HARDWARE WRITE PROTECTION: The WP pin can be connected to V

ing. Connecting the WP pin to V

the software write protection has been enabled. The software write protection register cannot be

programmed when the WP pin is connected to V

floating, the write protection mode is determined by the status of the software write protect

register.

Figure 7. Setting Permanent Write Protect Register (PSWP)

Figure 8. Setting Reversible Write Protect Register (RSWP)

Figure 9. Clearing Reversible Write Protect Register (RSWP)

S

T

A

R

T

S

T

O

P

SDA LINE

WORD

ADDRESS

DATA

CONTROL

BYTE

A

C

K

0 1 1 0 A2 A1 A0 0

A

C

K

A

C

K

= Don't Care

S

T

A

R

T

S

T

O

P

SDA LINE

WORD

ADDRESS

DATA

CONTROL

BYTE

A

C

K

01 1 0

0

A

C

K

A

C

K

1

00

= Don't Care

S

T

A

R

T

S

T

O

P

SDA LINE

WORD

ADDRESS

DATA

CONTROL

BYTE

A

C

K

01 1 0

0

A

C

K

A

C

K

1

01

= Don't Care