MCP98244 datasheet(34/52 Pages) MICROCHIP

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MCP98244

DS22327C-page 34

 2012-2013 Microchip Technology Inc.

5.3.4

WRITE PROTECTION

The MCP98244 has a Software Write-Protect (SWP)

feature that allows a 128-byte block to be write-pro-

tected. There are four 128-byte blocks. Each block is

write protected individually. The write-protected area

can be cleared by sending Clear Write Protect (CWP)

commands for each block.

To access write protection, the device address code of

the Address Byte is set to ‘0110’ instead of ‘1010’. In

this mode, the Slave Address pins are ignored. Once

the device is write protected it will not acknowledge any

write commands to the protected block. Table 5-5

shows the corresponding Address Bytes for the write-

protect feature.

5.3.4.1

SWP/RPS

The SWP (Software Write Protect) feature is invoked

by writing a command byte as shown on Table 5-5. It

can be cleared using the CWP command. In this mode,

the Slave Address pins are ignored. A high voltage VHV

needs to be applied to the A0 pin. RPS (Read Protec-

tion Status) can be executed to read protection status.

5.3.4.2

CWP (Clear Write Protect)

The CWP feature is invoked by writing clear write-pro-

tect command. A high voltage VHV needs to be applied

to the A0 pin and once the command is executed bank/

Page 0 and bank/Page 1 are cleared. Table 5-5 shows

the bit configuration.

TABLE 5-5:

DEVICE SLAVE ADDRESS DURING WRITE PROTECTION (SWP/CWP)

FIGURE 5-13:

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

Communication”).

EEPROM Function

Operation

Address Byte 23

A0 PIN Voltage

Address

Code 2

Slave Address 1, 2

R/W

SWP0/RPS0 — Bank/Page 0, Block 0

00h to 7Fh

SWP0  WRITE

0110

VHV

RPS0  READ 4

VDD, VSS, VHV

SWP1/RPS1 — Bank/Page 0, Block 1

80h to FFh

SWP1  WRITE

0110

VHV

RPS1  READ 4

VDD, VSS, VHV

SWP2/RPS2 — Bank/Page 1, Block 2

00h to 7Fh

SWP2  WRITE

0110

VHV

RPS2  READ 4

VDD, VSS, VHV

SWP3/RPS3 — Bank/Page 1, Block 3

80h to FFh

SWP3  WRITE

0110

VHV

RPS3  READ 4

VDD, VSS, VHV

CWP (Clear all Pages)

WRITE

0110

VHV

Note 1:

The slave address bits for each block are not binary increments for compatibility.

For Address Code <0110> the A0, A1, A2 states are ignored.

All address bytes, other than those indicated below, are ignored by the device.

The device will NAK if protected and ACK if it is unprotected.

SDA

567

SCL

Address Byte

MCP98244

Data

Word Address

MCP98244

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