mx25l12845e Macronix International Co., mx25l12845e Datasheet - Page 20

• Manufacturer Part Number: mx25l12845e
• Description: Mx25l12845e High Performance Serial Flash Specification Preliminary
• Manufacturer: Macronix International Co.

MX25L12845E
(9) 4 x I/O Read Mode (4READ)
The 4READ instruction enables quad throughput of Serial Flash in read mode. A Quad Enable (QE) bit of status
Register must be set to "1" before seding the 4READ instruction.The address is latched on rising edge of SCLK,
and data of every four bits(interleave on 4 I/O pins) shift out on the falling edge of SCLK at a maximum frequency
fQ. The first address byte can be at any location. The address is automatically increased to the next higher address
after each byte data is shifted out, so the whole memory can be read out at a single 4READ instruction. The ad-
dress counter rolls over to 0 when the highest address has been reached. Once writing 4READ instruction, the fol-
lowing address/dummy/data out will perform as 4-bit instead of previous 1-bit.
The sequence of issuing 4READ instruction is: CS# goes low→ sending 4READ instruction→ 24-bit address in-
terleave on SIO3, SIO2, SIO1 & SIO0→ 6 dummy cycles → data out interleave on SIO3, SIO2, SIO1 & SIO0→ to
end 4READ operation can use CS# to high at any time during data out (see Figure 22 for 4 x I/O Read Mode Tim-
ing Waveform).
Another sequence of issuing 4 READ instruction especially useful in random access is : CS# goes low→ sending
4 READ instruction→ 3-bytes address interleave on SIO3, SIO2, SIO1 & SIO0 →performance enhance toggling bit
P[7:0]→ 4 dummy cycles → data out still CS# goes high → CS# goes low (reduce 4 Read instruction) → 24-bit ran-
dom access address (see Figure 23 for 4x I/O Read Enhance Performance Mode timing waveform).
In the performance-enhancing mode (Note of Figure. 23), P[7:4] must be toggling with P[3:0] ; likewise
P[7:0]=A5h,5Ah,F0h or 0Fh can make this mode continue and reduce the next 4READ instruction. Once P[7:4] is
no longer toggling with P[3:0]; likewise P[7:0]=FFh,00h,AAh or 55h. These commands will reset the performance
enhance mode. And afterwards CS# is raised and then lowered, the system then will return to normal operation.
While Program/Erase/Write Status Register cycle is in progress, 4READ instruction is rejected without any impact
on the Program/Erase/Write Status Register current cycle.
(10) Fast Double Transfer Rate Read (FASTDTRD)
The FASTDTRD instruction is for doubling reading data out, signals are triggered on both rising and falling edge of
clock. The address is latched on both rising and falling edge of SCLK, and data of each bit shifts out on both rising
and falling edge of SCLK at a maximum frequency fC2. The 2-bit address can be latched-in at one clock, and 2-bit
data can be read out at one clock, which means one bit at rising edge of clock, the other bit at falling edge of clock.
The first address byte can be at any location.
The address is automatically increased to the next higher address after each byte data is shifted out, so the whole
memory can be read out at a single FASTDTRD instruction. The address counter rolls over to 0 when the highest
address has been reached.
The sequence of issuing FASTDTRD instruction is: CS# goes low → sending FASTDTRD instruction code (1bit
per clock) → 3-byte address on SI (2-bit per clock) → 6-dummy clocks (default) on SI → data out on SO (2-bit per
clock) → to end FASTDTRD operation can use CS# to high at any time during data out. (see Figure 19)
While Program/Erase/Write Status Register cycle is in progress, FASTDTRD instruction is rejected without any im-
pact on the Program/Erase/Write Status Register current cycle.
P/N: PM1428
REV. 0.06, MAR. 05, 2009
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