SST26WF040BA datasheet(93/96 Pages) MICROCHIP

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DS20005283C-page 93

SST26WF040B/040BA SST26WF080B/080BA

Classifying these sector/block sizes via the Sector

Type derived from JEDEC Flash Parameter Table:

SFDP address locations 4EH, 50H, and 52H is as fol-

lows:

• 8 KByte Blocks are classified as Sector Type 2

(@4EH of SFDP)

• 32 KByte Blocks are classified as Sector Type 3

(@50H of SFDP)

• 64 KByte Blocks are classified as Sector Type 4

(@52H of SFDP)

For the Number of Sectors associated with the contig-

uous sectors/blocks, a formula is used to determine the

number of sectors/blocks of these Sector Types:

• 8KByte Block (Type 2) is calculated by 2n. n is a

byte.

• 32KByte Block (Type 3) is calculated by 2n. n is a

byte.

• 64KByte Block (Type 4) is calculated by (2m - 2).

m can either be a 4, 5, 6, 7 or 8 depending on the

memory size. This m field is going to be used for

the 64KByte Block Section and will also be used

for the Block Protection Register Bit Location for-

mula.

m will have a constant value for specific densities and

is defined as:

• 8Mbit = 4

• 16Mbit = 5

• 32Mbit = 6

• 64Mbit = 7

• 128Mbit = 8

Block Protect Register Start/End Bits are mapped in the

SFDP by using the formula (2m + 1) + (c). “m” is a con-

stant value that represents the different densities from

8Mbit to 128Mbit (used also in the formula calculating

number of 64 KByte Blocks above). The values that are

going to be placed in the Block Protection Bit Start/End

field table are the constant value adder (c) in the for-

mula and are represented in two’s compliment except

when the value is 00H. If the value is 00H, this location

is the 0 bit location. If the value is other than 0, then this

is a constant value adder (c) that will be used in the for-

mula. The most significant (left most) bit indicates the

sign of the integer; it is sometimes called the sign bit.

If the sign bit is zero, then the number is greater than or

equal to zero, or positive. If the sign bit is one, then the

number is less than zero, or negative.

See Table 11-5 for an example of this formula.

8 KByte (Top Block)

Section 5: Sector Type Number

Section 5: Number of Sectors

Section 5: Block-Protection Register Bit Start Location

Section 5: Block-Protection Register Bit End Location

TABLE 11-4:

MEMORY BLOCK DIAGRAM REPRESENTATION

TABLE 11-5:

BPSL/BPEL EQUATION WITH ACTUAL CONSTANT ADDER DERIVED FROM THE

FORMULA (2M + 1) + (C)

Block Size

8 Mbit to 128 Mbit

Comments

8 KByte (Type 2) Bottom

BPSL = (2m + 1) + FFH

BPEL = (2m + 1) + 04H

0FFH = -1; 06H = 6

Odd address bits are Read-Lock bit

locations and even address bits are

Write-Lock bit locations.

32 KByte (Type3)

BPSL = BPEL= (2m + 1) + 0FDH

0FDH= -3

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