W988D6FB_13 Datasheet, PDF (22/66 Pages) Winbond – 256Mb Mobile LPSDR

W988D6FB / W988D2FB
8.1.12 Mode Register Set Command
256Mb Mobile LPSDR
( RAS = L, CAS = L, WE = L, BA0, BA1, A0~An = Register Data)
The Mode Register Set command is used to program the values of CAS latency, Addressing Mode and Burst Length in the
Mode Register. The default values in the Mode Register after power-up are undefined; therefore this command must be issued
during the power-up sequence and re-issued after the Deep Power Down Exit Command. Also, this command can be issued
while all banks are in the idle state.
8.1.13 No-Operation Command
( RAS = H, CAS = H, WE = H)
The No-Operation command is used in cases such as preventing the device from registering unintended commands. The device
performs no operation when this command is registered. This command is functionally equivalent to the Device Deselect
command.
8.1.14 Burst Stop Command
( RAS = H, CAS = H, WE = L)
The Burst stop command is used to stop the already activated burst operation. The activated page is left unclosed and future
commands can be issued to access the same page of the active bank. If this command is issued during a burst read operation,
the read data will go to a Hi-Z state after a delay equal to the CAS latency. If a burst stop command is issued during a burst
write operation, then the burst data is terminated and data bus goes to Hi-Z at the same clock that the burst command is
activated. Any remaining data from the burst write cycle is ignored.
8.1.15 Device Deselect Command
( CS = H)
The Device Deselect command disables the command decoder so that the RAS , CAS , WE and Address inputs are
ignored. This command is similar to the No-Operation command.
8.1.16 Auto Refresh Command
( RAS = L, CAS = L, WE = H, CKE = H, BA0, BA1, A0~An = Don’t care)
The Auto Refresh command is used to refresh the row address provided by the internal refresh counter. The Refresh operation
must be performed 8192 times within 64 ms. The next command can be issued after tRC from the end of the Auto Refresh
command. When the Auto Refresh command is issued, All banks must be in the idle state. The Auto Refresh operation is
equivalent to the CAS -before- RAS operation in a conventional DRAM.
8.1.17 Self Refresh Entry Command
( RAS = L, CAS = L, WE = H, CKE = L, BA0, BA1, A0~An = Don’t care)
When the Self Refresh Entry command is issued, the device enters the Self Refresh mode. While the device is in Self Refresh
mode, the device automatically refreshes memory cells, and all input and I/O buffers (except the CKE buffer) are disabled. By
asserting the CKE signal “high” (and by issuing the Self Refresh Exit command), the device exits the Self Refresh mode.
8.1.18 Self Refresh Exit Command
(CKE = H, CS = H or CKE = H, RAS = H, CAS = H)
This command is issued to exit out of the Self Refresh mode. One tRC delay is required prior to issuing any subsequent
command from the end of the Self Refresh Exit command.
8.1.19 Clock Suspend Mode Entry/Power Down Mode Entry Command
(CKE = L)
The internal CLK is suspended for one cycle when this command is issued (when CKE is asserted “low”). The device state is
held intact while the CLK is suspended. On the other hand, when the device is not operating the Burst cycle, this command
performs entry into Power Down mode. All input and output buffers (except the CKE buffer) are turned off in Power Down
mode.
8.1.20 Clock Suspend Mode Exit/Power Down Mode Exit Command
(CKE = H)
When the internal CLK has been suspended, operation of the internal CLK is resumed by providing this command (asserting
CKE “high”). When the device is in Power Down mode, the device exits this mode and all disabled buffers are turned on to the
active state. Any subsequent commands can be issued after one clock cycle from the end of this command.
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Publication Release Date : August 15, 2013
Revision A01-004