ACE25AA320GFMLTH datasheet(26/67 Pages) ACE

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ACE25AA320G

Serial NOR Flash Memory

3.0V Multi I/O with 4KB, 32KB & 64KB Sector/Block Erase

VER 1.2

Quad I/O Fast Read with ““8/16/32/64-Byte Wrap Around” in Standard SPI mod

The Quad I/O Fast Read command can be used to access a specific portion within a page by issuing “Set

Burst with Wrap” (77H) commands prior to EBH. The “Set Burst with Wrap” (77H) command can either

enable or disable the “Wrap Around” feature for the following EBH commands. When “Wrap Around” is

enabled, the data being accessed can be limited to either an 8/16/32/64-byte section of a 256-byte page.

The output data starts at the initial address specified in the command, once it reaches the ending

boundary of the 8/16/32/64-byte section, the output will wrap around the beginning boundary

automatically until CS# is pulled high to terminate the command.

The Burst with Wrap feature allows applications that use cache to quickly fetch a critical address and then

fill the cache afterwards within a fixed length (8/16/32/64-byte) of data without issuing multiple read

commands. The “Set Burst with Wrap” command allows three “Wrap Bits” W6-W4 to be set. The W4 bit is

used to enable or disable the “Wrap Around” operation while W6-W5 is used to specify the length of the

wrap around section within a page.

Quad I/O Fast Read (EBH) in QPI mode

The Quad I/O Fast Read command is also supported in QPI mode. See Figure12b. In QPI mode, the

number of dummy clocks is configured by the “Set Read Parameters (C0H)” command to accommodate a

wide range application with different needs for either maximum Fast Read frequency or minimum data

access latency.

Depending on the Read Parameter Bits P [5:4] setting, the number of dummy clocks can be configured as

either 4/6/8. When the dummy cycle is configured to 4, addr [0] input must be 0. In QPI mode, the

“Continuous Read Mode” bits M7-M0 are also considered as dummy clocks. “Continuous Read Mode”

feature is also available in QPI mode for Quad I/O Fast Read command. “Wrap Around” feature is not

available in QPI mode for Quad I/O Fast Read command. To perform a read operation with fixed data

length wrap around in QPI mode, a dedicated “Burst Read with Wrap” (0CH) command must be used.

Figure11b.Quad I/O Fast Read Sequence Diagram (M5-4=(1, 0))

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