M29DW128F datasheet(86/94 Pages) STMICROELECTRONICS

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High Voltage Block Protection

M29DW128F

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D.2

In-System technique

The In-System technique requires a high voltage level on the Reset/Blocks Temporary Unprotect pin, RP

(1). This can be achieved without violating the maximum ratings of the components on the

microprocessor bus, therefore this technique is suitable for use after the memory has been fitted to the

system.

To protect a group of blocks follow the flowchart in Figure 25: In-System equipment Group Protect

flowchart. To unprotect the whole chip it is necessary to protect all of the groups first, then all the groups

can be unprotected at the same time. To unprotect the chip follow Figure 26: In-System equipment Chip

Unprotect flowchart.

The timing on these flowcharts is critical. Care should be taken to ensure that, where a pause is

specified, it is followed as closely as possible. Do not allow the microprocessor to service interrupts that

will upset the timing and do not abort the procedure before reaching the end. Chip Unprotect can take

several seconds and a user message should be provided to show that the operation is progressing.

Note:

RP can be either at VIH or at VID when using the In-System Technique to protect the

Extended Block.

Table 42.

Programmer technique Bus operations, 8-bit or 16-bit mode

Operation

Address Inputs

A0-A22

Data Inputs/Outputs

DQ15A–1, DQ14-DQ0

Block (Group) Protect(1)

VIL

VID VIL Pulse

A9 = VID, A12-A22 Block Address

Others = X

Chip Unprotect

VID

VID VIL Pulse

A6 = VIH, A9 = VID, A12 = VIH,

A15 = VIH Others = X

Block (Group) Protect

Verify

VIL

VIH

A0 = VIL, A1 = VIH, A2-A7 = VIL,

A9 = VID, A12-A22 Block Address

Others = X

Pass = xx01h

Retry = xx00h.

Block (Group) Unprotect

Verify

VIL

VIH

A0 = VIL, A1 = VIH, A2 -A5 = VIL,

A6 = VIH, A7 = VIL,

A9 = VID, A12-A22 Block Address

Others = X

Pass = xx00h

Retry = xx01h.

Block Protection Groups are shown inAppendix A, Table 34.

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