T25D40AFIPR datasheet(13/74 Pages) HMSEMI

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registers may be used by system manufacturers to store and permanently protect security or other important

information separate from the main memory array.

5.2.1 Security Register 0

Serial Flash Discoverable Parameters (SFDP — JEDEC JESD216B):

This document defines the Serial Flash Discoverable Parameters (SFDP) revision B data structure for

HM25Q128A

family.

The Read SFDP (RSFDP) command (5Ah) reads information from a separate flash memory address

space for device identification, feature, and configuration information, in accord with the JEDEC JESD216B

standard for Serial Flash Discoverable Parameters.

The SFDP data structure consists of a header table that identifies the revision of the JESD216 header

format that is supported and provides a revision number and pointer for each of the SFDP parameter tables

that are provided. The parameter tables follow the SFDP header. However, the parameter tables may be

placed in any physical location and order within the SFDP address space. The tables are not necessarily

adjacent nor in the same order as their header table entries.

The SFDP header points to the following parameter tables:



Basic Flash

– This is the original SFDP table.

The physical order of the tables in the SFDP address space is: SFDP Header, and Basic Flash. The

SFDP address space is programmed byFSRKand read-only for the host system.

5.2.2 Serial Flash Discoverable Parameters (SFDP) Address Map

The SFDP address space has a header starting at address zero that identifies the SFDP data structure

and provides a pointer to each parameter. One Basic Flash parameter is mandated by the JEDEC JESD216B

standard.

Table 5.2 SFDP Overview Map — Security Register 0

Byte Address

Description

0000h

Location zero within JEDEC JESD216B SFDP space – start of SFDP header

0010h

Undefined space reserved for future SFDP header

0030h

Start of SFDP parameter

...

Remainder of SFDP JEDEC parameter followed by undefined space

006Fh

End of SFDP space

0070h to 00FFh

Reserved space

HM25Q128A

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