W641GG2JB Datasheet, PDF (45/109 Pages) Winbond – 1-Gbit GDDR3 Graphics SDRAM

W641GG2JB
1-Gbit GDDR3 Graphics SDRAM
6.6.6 DLL Reset
The normal operating mode is selected by issuing a MODE REGISTER SET command with bit A8 set to zero, and bits A0-A7 and
A9-A11 set to the desired values. A DLL reset is initiated by issuing a MODE REGISTER SET command with bit A8 set to one, and
bits A0-A7 and A9-A12 set to the desired values. The register bit is self clearing meaning that it returns back to the value ‗0‘ after
the DLL reset function has been issued.
6.6.7 Test mode
The normal operating mode is selected by issuing a MODE REGISTER SET command with bit A7 set to ‗0‘, and bitsA0-A6 and A8-
A11 set to the desired values. Programming bit A7 to ‗1‘ places the device into a test mode that isonly to be used by the DRAM
manufacturer. No functional operation is specified with test mode enabled.
6.7 Extended Mode Register Set Command (EMRS1)
The Extended Mode Register is used to control multiple operation modes of the device. The most important one is the
organization as a 1-CS or a 2-CS device. Furthermore, it is used to set the output driver impedance value, the
termination impedance value, the Write Recovery time value for Write with Autoprecharge. It is used as well to
enable/disable the DLL, to issue the Vendor ID. There is no default value for the Extended Mode Register. Therefore it
must be written after power up to operate the GDDR3 Graphics RAM. The Extended Mode Register can be
programmed by performing a normal Mode Register Set operation and setting the BA0 bit to HIGH. All other bits of the
EMR register are reserved and should be set to LOW. The Extended Mode Register must be loaded when all banks
are idle and no burst are in progress. The controller must wait the specified time tMRD before initiating any subsequent
operation (Figure : Extended Mode Register 1).
The timing of the EMRS command operation is equivalent to the timing of the MRS command operation.To apply an
EMRS command, CS0 has to be used.
- 45 -
Publication Release Date: Apr, 22, 2011
Revision A01-002