w942508bh Winbond Electronics Corp America, w942508bh Datasheet - Page 19

• Manufacturer Part Number: w942508bh
• Manufacturer: Winbond Electronics Corp America

16. FUNCTIONAL DESCRIPTION
Power Up Sequence
Command Function
1. Bank Activate Command
2. Bank Precharge Command
3. Precharge All Command
4. Write Command
( RAS = "L", CAS = "H", WE = "H", BS0, BS1 = Bank, A0 to A12 = Row Address)
The Bank Activate command activates the bank designated by the BS (Bank address) signal. Row
addresses are latched on A0 to A12 when this command is issued and the cell data is read out of
the sense amplifiers. The maximum time that each bank can be held in the active state is specified
as t
( RAS = "L", CAS = "H", WE = "L", BS0, BS1 = Bank, A10 = "L", A0 to A9, A11, A12 = Don’ t
care)
The Bank Precharge command percharges the bank designated by BS. The precharged bank is
switched from the active state to the idle state.
( RAS = "L", CAS = "H", WE = "L", BS0, BS1 = Don’t care, A10 = "H", A0 to A9, A11, A12 =
Don’t care)
The Precharge All command precharges all banks simultaneously. Then all banks are switched to
the idle state.
( RAS = "H", CAS = "L", WE = "L", BS0, BS1 = Bank, A10 = "L", A0 to A9, A11 = Column
Address)
(2)
(1)
(3)
(4)
(5)
(6)
(7)
(8)
RAS (max)
1) Apply V
2) Apply V
Apply power and attempt to CKE at a low state ( 0.2V), all other inputs may be undefined
Start Clock and maintain stable condition for 200 S (min.).
After stable power and clock, apply NOP and take CKE high.
Issue EMRS (Extended Mode Register Set) to enable DLL and establish Output Driver Type.
Issue MRS (Mode Register Set) to reset DLL and set device to idle with bit A8.
(an additional 200 cycles(min) of clock are required for DLL Lock)
Issue precharge command for all banks of the device.
Issue two or more Auto Refresh commands.
Issue MRS-Initialize device operation.
(If device operation mode is set at sequence 5, sequence 8 can be skipped.)
. After this command is issued, Read or Write operation can be executed.
DD
DDQ
before or at the same time as V
before or at the same time as V
- 19 -
DDQ
TT
.
and V
Publication Release Date: March 19, 2002
REF
.
W942508BH
Revision A1