MCP98243 datasheet(39/62 Pages) MICROCHIP

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DS22153C-page 39

MCP9843/98243

5.3.3.3

PWP (Permanent Write Protect)

Once the PWP register is written, the lower half of the

memory will be permanent protected and the device

will not acknowledge any command. The protected

area of the memory can not be cleared, reversed, or re-

written. If a write is attempted to the protected area, the

device will acknowledge the address byte and word

address but not the data byte. (See Table 5-4 and

Table 5-5).

Unlike SWP and CWP, a VHV is not applied on the A0

pin to execute PWP. The state of A2, A1, and A0 is user

selectable. However, the address pin states need to

match the slave address bits, as shown in Table 5-3.

FIGURE 5-17:

Timing Diagram for Setting Permanent Write Protect (See Section 4.0 “Serial

Communication”).

Note:

Once the Permanent Write-Protect is

executed, it cannot be reversed, even if the

device power is cycled. See Figure 2-13

for VHV voltage levels.

SDA

345

SCL

Address Byte

MCP98243

567

Data

Word Address

MCP98243

Note:

Unlike SWP and CWP, VHV must be within the range of GND to VDD + 1V to execute PWP.

See Figure 2-13 and Section 5.3.3 “Write Protection”.

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