26VF064B-ISLASHTD datasheet(71/76 Pages) MICROCHIP

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Advance Information

DS25119C-page 71

SST26VF064B / SST26VF064BA

Classifying these sector/block sizes via the Sector

Type derived from JEDEC Flash Parameter Table:

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

lows:

• 8KByte Blocks are classified as Sector Type 1

(@4CH of SFDP)

• 32KByte Blocks are classified as Sector Type 2

(@4EH of SFDP)

• 64KByte Blocks are classified as Sector Type 3

(@50H 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 1) is calculated by 2n. n is a

byte.

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

byte.

• 64KByte Block (Type 3) 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 64Kbyte 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 11-4 for an example of this formula.

TABLE 11-3:

MEMORY BLOCK DIAGRAM REPRESENTATION

8 KByte Bottom Block

(from 000000H)

Section 1: Sector Type 1

Section 1: Number of Sectors

Section 1: Block-Protection Register Bit Start Location

Section 1: Block-Protection Register Bit End Location

32 KByte

Section 2: Sector Type Number

Section 2: Number of Sectors

Section 2: Block-Protection Register Bit Start Location

Section 2: Block-Protection Register Bit End Location

64 KByte

Section 3: Sector Type Number

Section 3: Number of Sectors

Section 3: Block-Protection Register Bit Start Location

Section 3: Block-Protection Register Bit End Location

32 KByte

Section 4: Sector Type Number

Section 4: Number of Sectors

Section 4: Block-Protection Register Bit Start Location

Section 4: Block-Protection Register Bit End Location

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

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