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2Gb: x4, x8, x16 DDR3 SDRAM - Micron

2Gb: x4, x8, x16 DDR3 SDRAM - Micron

2Gb: x4, x8, x16 DDR3 SDRAM - Micron

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ZQ CALIBRATION Operation<br />

The ZQ CALIBRATION command is used to calibrate the DRAM output drivers (RON) and ODT values (RTT) over process, voltage, and temperature, provided a dedicated<br />

240��(±1%) external resistor is connected from the DRAM’s ZQ ball to VSSQ. <strong>DDR3</strong> <strong>SDRAM</strong> require a longer time to calibrate RON and ODT at power-up initialization<br />

and self refresh exit, and a relatively shorter time to perform periodic calibrations.<br />

<strong>DDR3</strong> <strong>SDRAM</strong> defines two ZQ CALIBRATION commands: ZQCL and ZQCS. An example<br />

of ZQ calibration timing is shown below.<br />

All banks must be precharged and tRP must be met before ZQCL or ZQCS commands<br />

can be issued to the DRAM. No other activities (other than issuing another ZQCL or<br />

ZQCS command) can be performed on the DRAM channel by the controller for the duration<br />

of tZQinit or tZQoper. The quiet time on the DRAM channel helps accurately calibrate<br />

RON and ODT. After DRAM calibration is achieved, the DRAM should disable the<br />

ZQ ball’s current consumption path to reduce power.<br />

ZQ CALIBRATION commands can be issued in parallel to DLL RESET and locking time.<br />

Upon self refresh exit, an explicit ZQCL is required if ZQ calibration is desired.<br />

In dual-rank systems that share the ZQ resistor between devices, the controller must not<br />

enable overlap of tZQinit, tZQoper, or tZQCS between ranks.<br />

Figure 63: ZQ CALIBRATION Timing (ZQCL and ZQCS)<br />

CK#<br />

CK<br />

Command<br />

T0 T1 Ta0 Ta1 Ta2 Ta3 Tb0 Tb1 Tc0 Tc1 Tc2<br />

ZQCL NOP NOP NOP Valid Valid ZQCS NOP NOP NOP Valid<br />

Address Valid Valid<br />

Valid<br />

A10 Valid Valid<br />

Valid<br />

CKE 1 Valid Valid 1<br />

Valid<br />

ODT 2 Valid Valid 2 Valid<br />

DQ 3 High-Z Activities 3<br />

High-Z<br />

t ZQinit or t ZQoper<br />

<strong>2Gb</strong>: <strong>x4</strong>, <strong>x8</strong>, <strong>x16</strong> <strong>DDR3</strong> <strong>SDRAM</strong><br />

ZQ CALIBRATION Operation<br />

t ZQCS<br />

Indicates break<br />

in time scale<br />

Activities<br />

Don’t Care<br />

Notes: 1. CKE must be continuously registered HIGH during the calibration procedure.<br />

2. ODT must be disabled via the ODT signal or the MRS during the calibration procedure.<br />

3. All devices connected to the DQ bus should be High-Z during calibration.<br />

PDF: 09005aef826aaadc<br />

<strong>2Gb</strong>_<strong>DDR3</strong>_<strong>SDRAM</strong>.pdf – Rev. P 2/12 EN 154 <strong>Micron</strong> Technology, Inc. reserves the right to change products or specifications without notice.<br />

� 2006 <strong>Micron</strong> Technology, Inc. All rights reserved.

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