AM29PDL128G datasheet(31/71 Pages) AMD

31 / 71 page

Am29PDL128G

October 28, 2004

P R E L IM IN A R Y

pass functions are not available when programming

the SecSi Sector.

The SecSi Sector area can be protected using one of

the following procedures:

Write the three-cycle Enter SecSi Sector Region

command sequence, and then follow the in-system

sector protect algorithm as shown in Figure 1, ex-

cept that

RESET# may be at either VIH or VID. This

allows in-system protection of the SecSi Sector Re-

gion without raising any device pin to a high voltage.

Note: This method is only applicable to the SecSi

Sector.

To verify the protect/unprotect status of the SecSi

Sector, follow the algorithm shown in Figure 3.

Once the SecSi Sector is locked and verified, the sys-

tem must write the Exit SecSi Sector Region com-

mand sequence to return to reading and writing the

remainder of the array.

The SecSi Sector lock must be used with caution

since, once locked, there is no procedure available for

unlocking the SecSi Sector area and none of the bits

in the SecSi Sector memory space can be modified in

any way.

SecSi Sector Protection Bit

The SecSi Sector Protection Bit prevents program-

ming of the SecSi Sector memory area. Once set, the

SecSi Sector memory area contents are non-modifi-

able.

Utilizing Password and SecSi Sector Concurrently

The password must be stored in the first eight bytes of

the SecSi Sector. Once the device is permanently

locked into the Password Protection Mode, the erase,

program, and read operation no longer work on those

eight bytes of password in the SecSi Sector. Once the

SecSi Sector protection bit is programmed, no location

in the SecSi Sector may be programmed. To use both

Password Protection and the SecSi Sector concur-

rently, the user must always program the password

into the first eight bytes of the SecSi Sector

before ei-

ther the Password Protection Mode is selected or the

SecSi Sector protection bit is programmed.

Method 1

1. Enter the SecSi Sector by issuing the SecSi Sector

Entry command.

2. Program the 64-bit password by issuing the Pass-

word Program and Password Verify commands

3. Lock the password by issuing the Password Protec-

tion Mode Locking Bit Program command.

4. Program the SecSi Sector, excluding bytes 0–7.

5. Lock the SecSi Sector by issuing the SecSi Sector

Protection Bit Program command.

6. Exit the SecSi Sector by issuing the SecSi Sector

Exit or Reset command

Note: Step 4 may be performed prior to Step 2.

Method 2

1. Enter the SecSi Sector by issuing the SecSi Sector

Entry command.

2. Program the entire SecSi Sector, including the first

eight bytes contain the 64-bit password.

3. Lock the password by issuing the Password Protec-

tion Mode Locking Bit Program command.

4. Lock the SecSi Sector by issuing the SecSi Sector

Protection Bit Program command.

5. Exit the SecSi Sector by issuing the SecSi Sector

Exit or Reset command

Note: Step 4 may be performed prior to Step 3.

Figure 3.

SecSi Sector Protect Verify

Hardware Data Protection

The command sequence requirement of unlock cycles

for programming or erasing provides data protection

against inadvertent writes. In addition, the following

hardware data protection measures prevent accidental

erasure or programming, which might otherwise be

caused by spurious system level signals during V

power-up and power-down transitions, or from system

noise.

Write 60h to

any address

Write 40h to SecSi

Sector address

with A6 = 0,

A1 = 1, A0 = 0

START

RESET# =

VIH or VID

Wait 1

µs

Read from SecSi

Sector address

with A6 = 0,

A1 = 1, A0 = 0

If data = 00h,

SecSi Sector is

unprotected.

If data = 01h,

SecSi Sector is

protected.

Remove VIH or VID

from RESET#

Write reset

command

SecSi Sector

Protect Verify

complete

AM29PDL128G 数据表(PDF) 31 Page - Advanced Micro Devices

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