PC48F4400PLXB0 datasheet(85/102 Pages) NUMONYX

85 / 102 page

November 2007

Datasheet

Order Number: 290701-18

Numonyx™ Wireless Flash Memory (W18)

If RCR[3]=1 (no-wrap mode) and RCR[2:0] = 1h (4-word burst length), then possible

linear burst sequences are 0-1-2-3, 1-2-3-4, 2-3-4-5, and 3-4-5-6. RCR[3]=1 not only

enables limited non-aligned sequential bursts, but also reduces power by minimizing

the number of internal read operations.

Setting RCR[2:0] bits for continuous linear burst mode (7h) also achieves the above 4-

word burst sequences. However, significantly more power may be consumed. The 1-2-

3-4 sequence, for example, consumes power during the initial access, again during the

internal pipeline lookup as the processor reads word 2, and possibly again, depending

on system timing, near the end of the sequence as the device pipelines the next 4-word

sequence. RCR[3]=1 while in 4-word burst mode (no-wrap mode) reduces this excess

power consumption.

14.10

Burst Length (RCR[2:0])

The Burst Length bit (BL[2:0]) selects the number of words the device outputs in

synchronous read access of the flash memory array. The burst lengths are 4-word, 8-

word, 16-word, and continuous word.

Continuous-burst accesses are linear only, and do not wrap within any word length

boundaries (see Table 35, “Sequence and Burst Length” on page 84). When a burst

cycle begins, the device outputs synchronous burst data until it reaches the end of the

“burstable” address space.

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