AS4C128M16D2 datasheet(21/75 Pages) ALSC

21 / 75 page

AS4C128M16D2

Confidential

Version

2.0 – Oct/2014

Burst Mode Operation

Burst mode operation is used to provide a constant flow of data to memory locations (write cycle), or from memory

locations (read cycle). The parameters that define how the burst mode will operate are burst sequence and burst

length.

The DDR2 SDRAM supports 4 bit and 8 bit burst modes only. For 8 bit burst mode, full interleave address ordering is

supported, however, sequential address ordering is nibble based for ease of implementation. The burst length is

programmable and defined by the addresses A0 ~ A2 of the MRS. The burst type, either sequential or interleaved, is

programmable and defined by the address bit 3 (A3) of the MRS. Seamless burst read or write operations are

supported.

Interruption of a burst read or write operation is prohibited, when burst length = 4 is programmed. For burst

interruption of a read or write burst when burst length = 8 is used, see the “Burst Interruption” section of this

datasheet. A Burst Stop command is not supported on DDR2 SDRAM devices.

Burst Length and Sequence

Burst Length

Starting Address (

A2 A1 A0 )

Sequential Addressing (decimal)

Interleave Addressing (decimal)

x 0 0

0, 1, 2, 3

x 0 1

1, 2, 3, 0

1, 0, 3, 2

x 1 0

2, 3, 0, 1

x 1 1

3, 0, 1, 2

3, 2, 1, 0

0 0 0

0, 1, 2, 3, 4, 5, 6, 7

0 0 1

1, 2, 3, 0, 5, 6, 7, 4

1, 0, 3, 2, 5, 4, 7, 6

0 1 0

2, 3, 0, 1, 6, 7, 4, 5

0 1 1

3, 0, 1, 2, 7, 4, 5, 6

3, 2, 1, 0, 7, 6, 5, 4

1 0 0

4, 5, 6, 7, 0, 1, 2, 3

1 0 1

5, 6, 7, 4, 1, 2, 3, 0

5, 4, 7, 6, 1, 0, 3, 2

1 1 0

6, 7, 4, 5, 2, 3, 0, 1

1 1 1

7, 4, 5, 6, 3, 0, 1, 2

7, 6, 5, 4, 3, 2, 1, 0

Note: 1) Page length is a function of I/O organization and column addressing.

2) Order of burst access for sequential addressing is “nibble-based” and therefore different from SDR or DDR

components.

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