MX25L12835F
9-11. Read Data Bytes at Higher Speed (FAST_READ)
The FAST_READ instruction is for quickly reading data out. The address is latched on rising edge of SCLK, and
data of each bit shifts out on the falling edge of SCLK at a maximum frequency fC. 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 FAST_READ instruction. The address counter rolls over to 0 when
the highest address has been reached.
Read on SPI Mode The sequence of issuing FAST_READ instruction is: CS# goes low→ sending FAST_READ
instruction code→ 3-byte address on SI→ 8 dummy cycles (default)→ data out on SO→ to end FAST_READ opera-
tion can use CS# to high at any time during data out.
In the performance-enhancing mode, 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]; like-
wise P[7:0]=FFh,00h,AAh or 55h and afterwards CS# is raised and then lowered, the system then will escape from
performance enhance mode and return to normal operation.
While Program/Erase/Write Status Register cycle is in progress, FAST_READ instruction is rejected without any im-
pact on the Program/Erase/Write Status Register current cycle.
Figure 27. Read at Higher Speed (FAST_READ) Sequence (SPI Mode)
CS#
0
1
2
3
4
5
6
7
8
9
10
28 29 30 31
Mode 3
Mode 0
SCLK
Command
0Bh
24-Bit Address
SI
23 22 21
3
2
1
0
High-Z
SO
CS#
47
32 33 34 35 36 37 38 39 40 41 42 43 44 45 46
SCLK
Configurable
Dummy Cycle
7
6
5
4
3
2
0
1
SI
DATA OUT 2
DATA OUT 1
7
6
5
4
3
2
1
0
7
7
6
5
4
3
2
0
1
SO
MSB
MSB
MSB
P/N: PM1795
REV. 1.0, OCT. 23, 2012
39
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