Vizio VX37L HDTV10A, Service Manual, Page: 71 / 147

CONFIDENTIAL
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DO NOT COPY Page
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40
File No. SG-0209
DLL Enable/Disable
The DLL must be enabled for normal operation. DLL enable is required during power up
initialization, and upon returning to normal operation after having disabled the DLL for the
purpose of debug or evaluation.
The DLL is automatically disabled when entering self refresh operation and is automatically
re-enabled upon exit of self refresh operation. Any time the DLL is enabled, 200 clock cycles
must occur to allow time for the internal clock to lock to the externally applied clock before a
Read command can be issued.
This is the reason for introducing timing parameter tXSRD for DDR SDRAM’s (Exit Self
Refresh to Read Command). Non- Read commands can be issued 2 clocks after the DLL is
enabled via the EMRS command (tMRD) or 10 clocks after the DLL is enabled via self
refresh exit command (tXSNR, Exit Self Refresh to Non-Read Command).