SE97BTP datasheet(17/53 Pages) NXP

17 / 53 page

SE97B_1

Product data sheet

Rev. 01 — 27 January 2010

17 of 53

NXP Semiconductors

SE97B

DDR memory module temp sensor with integrated SPD

7.10.1.3

Acknowledge polling

Acknowledge polling can be used to determine if the SE97B is busy writing or is ready to

accept commands. Polling is implemented by sending a ‘Selective Read’ command

(described in Section 7.10.3 “Read operations”) to the device. The SE97B will not

acknowledge the slave address as long as internal write is in progress.

7.10.2 Memory Protection

The lower half (the first 128 bytes) of the memory can be write protected by special

EEPROM commands without an external control pin. The SE97B features three types of

memory write protection instructions, and three respective read Protection instructions.

The level of write-protection (set or clear) that has been defined using these instructions

remained defined even after power cycle.

The memory protection commands are:

• Permanent Write Protection (PWP)

• Reversible Write Protection (RWP)

• Clear Write Protection (CWP)

• Read Permanent Write Protection (RPWP)

• Read Reversible Write Protection (RRWP)

• Read Clear Write Protection (RCWP)

Table 6 is the summary for normal and memory protection instructions.

[1]

The most significant bit, bit 7, is sent first.

[2]

VI(ov) ranges from 7.0 V to 10 V.

[3]

A0, A1, and A2 are compared against the respective external pins on the SE97B. Do not apply VI(ov) to the A0 pin during

Normal EEPROM read/write, Permanent Write Protection (PWP) and Read PWP.

This special EEPROM command consists of a unique 4-bit fixed address (0110b) and the

voltage level applied on the 3-bit hardware address. Normally, to address the memory

array, the 4-bit fixed address is ‘1010b’. To access the memory protection settings, the

4-bit fixed address is ‘0110b’. Figure 13 and Figure 14 show the write and read protection

sequence, respectively.

Table 6.

EEPROM commands summary

Command

Fixed address

Hardware selectable

address

R/W

Bit 7[1]

Bit 6

Bit 5

Bit 4

Bit 3

Bit 2

Bit 1

Bit 0

Normal EEPROM read/write

1010A2

R/W

Reversible Write Protection (RWP)

0110VSS

VSS

VI(ov)[2]

Clear Reversible Write Protection (CRWP)

0110VSS

VDD

VI(ov)[2]

Permanent Write Protection (PWP)[3]

0110A2

Read RWP

0110VSS

VSS

VI(ov)[2]

Read CRWP

0110VSS

VDD

VI(ov)[2]

Read PWP

0110A2

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