DDR2 Application Note

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Annabella Woods
6 years ago
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1 DDR2 ODT(On Die Termination) Control March 2006 Engineering Team MEMORY DIVISION SAMSUNG ELECTRONICS Co., LTD

2 DDR2 ODT (On Die Termination) On board termination resistance is integrated inside of Motherboard Termination(MBT) On Die Termination (ODT) Controller Slot Slot On Board termination Vtt Controller Slot Slot

3 On Die Termination On/Off Control ODT turn on/off is controlled by ODT pin One ODT control pin per : Turn-on or Turn-off control Two ODT control pin per DIMM to support rank by rank control But in most application, one ODT pin per slot is being used DDR2 Rtt ODT On/Off Control ODT high active ODT turn-on period SW Controller ODT pin CK ODT ODT On ODT Off Input buffer Input pin Source DQ, DQS, DQS#, RDQS, RDQS# tis setup time ODT turn on delay time taond = 2*tCK taofd = 2.5*tCK ODT turn off delay time

4 On Die Termination Value Selection should be determined during power-up by EMRS SW2 SW1 300 ohm 300 ohm 300 ohm VDD Address Field A9 A8 A7 A6 BA A5 BA A4 MRS Mode MRS EMRS(1) EMRS(2) EMRS(3) : Reserved A3 A2 A1 A0 SW1 SW2 300 ohm 300 ohm 300 ohm Control Circuit VSS DQ, DQS, DM Pin ODT Pin OCD program EMRS(1) Rtt A Additive latency Rtt D.S A2 Rtt (Nominal) 0 ODT Disabled DLL SW1 on ODT on SW2 on

5 Test Condition for ODT Verification Capacitance Specification for DDR2-667 & 800 Parameter DDR2-667/DDR2-800 MIN MAX UNIT Input capacitance CK, /CK pf Input capacitance Delta, CK, /CK pf Input capacitance C/A pf Input capacitance Delta, C/A pf Input capacitance DQ/DM/DQS pf Input capacitance Delta, DQ/DM/DQS pf

ODT Case Study @DDR2-667 Writes For two slot

6 ODT Case Writes For two slot population, 50ohm seems to be better than 75ohm in term of signal integrity For one slot population, even 150ohm seems O.K. 2R X X 2R 1R X X 1R

7 ODT Case Writes For two slot population, 50ohm seems to be better than 75ohm in term of signal integrity For one slot population, even 150ohm seems O.K. 2R X X 2R 1R X X 1R

8 Recommended ODT Control - Writes Termination Matrix for Writes to Configuration 2R Empty Empty 2R 1R Empty Empty 1R Write To Controller Target DQ ODT Resistance RTT Module in Module in Rank 1 Rank 2 Rank 1 Rank 2 75 or 75 or 75 or Unpopulated 75 or Unpopulated Unpopulated 75 or 75 or Unpopulated Unpopulated 75 or Unpopulated 75 or Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated ODT on a controller always turned-off Example : (write to ) R1 R2 R1 R2 Vtt Memory Controller 75 or Slot 1 Slot 2

ODT Case Study @DDR2-667 Reads For two slot

9 ODT Case Reads For two slot population, either 75ohm or 50ohm could be O.K. 50ohm does not help on reads that much For one slot population, even 150ohm seems O.K. 2R X X 2R 1R X X 1R

10 ODT Case Reads For two slot population, either 75ohm or 50ohm could be O.K. 50ohm does not help on reads that much For one slot population, even 150ohm seems O.K. 2R X X 2R 1R X X 1R

11 Recommended ODT Control - Reads Termination Matrix for Reads to Configuration 2R Empty Empty 2R 1R Empty Empty 1R Read from Controller Target DQ ODT Resistance RTT Module in Module in Rank 1 Rank 2 Rank 1 Rank 2 75 or 75 or 75 or Unpopulated 75 or Unpopulated Unpopulated 75 or 75 or Unpopulated Unpopulated 75 or Unpopulated 75 or Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated Unpopulated ODT on a controller always turned-on Example : (Read from ) R1 R2 R1 R2 Vtt Memory Controller 75 or Slot 1 Slot 2

12 Summary of ODT Control should be decided depending on channel environment and set during initialization sequence For one slot/channel implementation, 150ohm seems O.K. For two slots/channel implementation, need to be determined properly For DDR2-400/533, 75ohm seems O.K. For DDR2-667/800, 50ohm is better than 75ohm ODT trun-on/off is controlled by ODT pin There re more possible termination methods, but not covered in this material For example, 37.5ohm termination is possible with both ODTs turned-on on a dual rank DIMM, which may result better signal integrity, but relatively small voltage swing and more power consumption.

User s Guide DDR2 Compliance Test

User s Guide DDR2 Compliance Test Rev. 1, June 2010 1 Introduction...2 1.1 Probes Needed...4 2 All in Sequence...4 2.1 Single-Ended AC Input Tests, Address and Control...4 2.2 Single-Ended AC Tests, Data,