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OneNAND512/OneNAND1GDDP
FLASH MEMORY
50
Read Operation
The device has two read configurations ; Asynchronous read and Synchronous burst read.
The initial state machine makes the device to be automatically entered into asynchronous read mode to prevent the memory content
from spurious altering upon device power up or after a hardware reset. No commands are required to retrieve data in asynchronous
mode. The synchronous mode will be enabled by setting RM bit of System configuration1 register to Synchronous read mode.
Asynchronous Read Mode (RM = 0)
For the asynchronous read mode a valid address should be asserted on ADD0-ADD15, while driving AVD and CE to V
IL
. WE
should remain at V
IH
. The data will appear on ADD15-ADD0. Address access time (t
AA
) is equal to the delay from valid addresses to
valid output data. The chip enable access time(t
CE
) is the delay from the falling edge of CE to valid data at the outputs. The output
enable access time(t
OE
) is the delay from the falling edge of OE to valid data at the output.
Synchronous (Burst) Read Mode
(RM = 1)
The device is capable of continuous linear burst operation and linear burst operation of a preset length. For the burst mode, the host
should determine how many clock cycles are desired for the initial word(t
IAA
) of each burst access using BRL bit of System configura-
tion 1 register. The registers also can be read during burst read mode by using AVD signal with a address. To initiate the synchro-
nous read again, a new address during CE low toggle is needed after the host has completed status reads or the device has
completed the program or erase operation.
Continuous Linear Burst Read
The initial word is output t
IAA
after the rising edge of the first CLK cycle. Subsequent words are output t
BA
after the rising edge of each
successive clock cycle, which automatically increments the internal address counter. The RDY output indicates this condition to the
system by pulsing low. The device will continue to output sequential burst data, wrapping around after it reaches the designated loca-
tion(See Figure 12 for address map information) until the system asserts CE high, RP low or AVD low in conjunction with a new
address. The cold/warm/hot reset or asserting CE high or WE low pulse terminate the burst read operation.
If the device is accessed synchronously while it is set to asynchronous read mode, it is possible to read out the first data
without problems.
Division
Add.map(word order)
BootM(0.5Kw)
0000h~01FFh
Buffer0
BufM 0(1Kw)
0200h~05FFh
BufM 1(1Kw)
0600h~09FFh
Buffer1
Reserved Main
0A00h~7FFFh
N/A Reg.
BootS(16w)
8000H~800Fh
Buffer0
BufS 0(32w)
8010h~802Fh
BufS 1(32w)
8030h~804Fh
Buffer1
Reserved Spare
8050h~8FFFh
N/A Reg.
Reserved Reg.
9000h~EFFFh
Register(4Kw)
F000h~FFFFh
Reg.
Not Support
Not Support
Not Support
Figure 12. The boundary of synchronous read
* Reserved area is not available on Synchronous read