High Voltage Block Protection
M29DW128F
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
Address Inputs
Data Inputs/Outputs
DQ15A–1, DQ14-DQ0
Operation
E
G
W
A0-A22
A9 = VID, A12-A22 Block Address
Others = X
Block (Group) Protect(1) VIL
VID VIL Pulse
X
X
A6 = VIH, A9 = VID, A12 = VIH,
A15 = VIH Others = X
Chip Unprotect
VID VID VIL Pulse
A0 = VIL, A1 = VIH, A2-A7 = VIL,
A9 = VID, A12-A22 Block Address
Pass = xx01h
Retry = xx00h.
Block (Group) Protect
Verify
VIL
VIL
VIH
Others = X
A0 = VIL, A1 = VIH, A2 -A5 = VIL,
A6 = VIH, A7 = VIL,
Pass = xx00h
Block (Group) Unprotect
Verify
VIL
VIL
VIH
A9 = VID, A12-A22 Block Address
Others = X
Retry = xx01h.
1. Block Protection Groups are shown inAppendix A, Table 34.
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NUMONYX [ NUMONYX B.V ]
