128Mb DDR SDRAM
3.2 Basic Functionality
3.2.1 Power-Up and Initialization Sequence
The following sequence is required for POWER UP and Initialization.
1. Apply power and attempt to maintain CKE at a low state(all other inputs may be undefined.)
- Apply VDD before or at the same time as VDDQ.
- Apply VDDQ before or at the same time as VTT & Vref.
2. Start clock and maintain stable condition for a minimum of 200us.
3. The minimum of 200us after stable power and clock(CK, CK), apply NOP & take CKE high.
4. Issue precharge commands for all banks of the device.
*1 5. Issue EMRS to enable DLL.(To issue "DLL Enable" command, provide "Low" to A0, "High" to BA0 and "Low"
to all of the rest address pins, A1~A11 and BA1)
*1 6. Issue a mode register set command for "DLL reset". The additional 200 cycles of clock input is required to
lock the DLL.
(To issue DLL reset command, provide "High" to A8 and "Low" to BA0)
*2 7. Issue precharge commands for all banks of the device.
8. Issue 2 or more auto-refresh commands.
9. Issue a mode register set command with low to A8 to initialize device operation.
*1 Every "DLL enable" command resets DLL. Therefore sequence 6 can be skipped during power up.
Instead of it, the additional 200 cycles of clock input is required to lock the DLL after enabling DLL.
*2 Sequence of 6 & 7 is regardless of the order.
Power up & Initialization Sequence
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
2 Clock min. 2 Clock min.
2 Clock min.
Figure 4. Power up and initialization sequence
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REV. 1.0 November. 2. 2000