2GB-DDR3L-AS4C256M8D3L Datasheet, PDF (10/86 Pages) Alliance Semiconductor Corporation – Bidirectional differential data strobe

2Gb DDR3L - AS4C256M8D3L
 Power-up and Initialization
The Following sequence is required for POWER UP and Initialization.
1. Apply power (RESET# is recommended to be maintained below 0.2 x VDD, all other inputs may be undefined).
RESET# needs to be maintained for minimum 200us with stable power. CKE is pulled “Low” anytime before
RESET# being de-asserted (min. time 10ns). The power voltage ramp time between 300mV to VDDmin must be
no greater than 200ms; and during the ramp, VDD>VDDQ and (VDD-VDDQ) <0.3 Volts.
- VDD and VDDQ are driven from a single power converter output, AND
- The voltage levels on all pins other than VDD, VDDQ, VSS, VSSQ must be less than or equal to VDDQ and VDD
on one side and must be larger than or equal to VSSQ and VSS on the other side. In addition, VTT is limited to
0.95V max once power ramp is finished, AND
- Vref tracks VDDQ/2.
OR
- Apply VDD without any slope reversal before or at the same time as VDDQ.
- Apply VDDQ without any slope reversal before or at the same time as VTT & Vref.
- The voltage levels on all pins other than VDD, VDDQ, VSS, VSSQ must be less than or equal to VDDQ and VDD
on one side and must be larger than or equal to VSSQ and VSS on the other side.
2. After RESET# is de-asserted, wait for another 500us until CKE become active. During this time, the DRAM will
start internal state initialization; this will be done independently of external clocks.
3. Clock (CK, CK#) need to be started and stabilized for at least 10ns or 5tCK (which is larger) before CKE goes
active. Since CKE is a synchronous signal, the corresponding set up time to clock (tIS) must be meeting. Also a
NOP or Deselect command must be registered (with tIS set up time to clock) before CKE goes active. Once the
CKE registered “High” after Reset, CKE needs to be continuously registered “High” until the initialization sequence
is finished, including expiration of tDLLK and tZQinit.
4. The DDR3L DRAM will keep its on-die termination in high impedance state as long as RESET# is asserted.
Further, the DRAM keeps its on-die termination in high impedance state after RESET# deassertion until CKE is
registered HIGH. The ODT input signal may be in undefined state until tIS before CKE is registered HIGH. When
CKE is registered HIGH, the ODT input signal may be statically held at either LOW or HIGH. If RTT_NOM is to be
enabled in MR1, the ODT input signal must be statically held LOW. In all cases, the ODT input signal remains
static until the power up initialization sequence is finished, including the expiration of tDLLK and tZQinit.
5. After CKE being registered high, wait minimum of Reset CKE Exit time, tXPR, before issuing the first MRS
command to load mode register.(tXPR=max (tXS, 5tCK))
6. Issue MRS command to load MR2 with all application settings. (To issue MRS command for MR2, provide “Low”
to BA0 and BA2, “High” to BA1)
7. Issue MRS Command to load MR3 with all application settings. (To issue MRS command for MR3, provide “Low”
to BA2, “High” to BA0 and BA1)
8. Issue MRS Command to load MR1 with all application settings and DLL enabled. (To issue “DLL Enable”
command, provide “Low” to A0, “High” to BA0 and “Low” to BA1 and BA2)
9. Issue MRS Command to load MR0 with all application settings and “DLL reset”. (To issue DLL reset command
provide “High” to A8 and “Low” to BA0-BA2)
10. Issue ZQCL command to starting ZQ calibration.
11. Wait for both tDLLK and tZQinit completed.
12. The DDR3L SDRAM is now ready for normal operation.
Confidential
10
Rev. 2.0
Aug. /2014