GS4901B Datasheet, PDF (20/95 Pages) Gennum Corporation – SD Clock and Timing Generator with GENLOCK

GS4901B/GS4900B Preliminary Data Sheet
1.4 Pre-Programmed Recognized Video Standards
Table 1-2 describes the video standards recognized by the GS4901B/GS4900B.
The device will automatically recognize VID_STD[5:0] = 1 to 10. In order to enable
the device to recognize and lock to any of the HD reference formats defined by
VID_STD[5:0] = 11 to 38, the user must set the corresponding bit LOW in the
Reference_Standard_Disable register, located at address 11h-13h of the host
interface. In addition, the user must set the HD_Reference_Enable bit of register
82h[7] HIGH.
Please see the descriptions of the Reference_Standard_Disable and
HD_Reference_Enable registers in Section 3.10.3 on page 66.
If an HD reference format is left disabled in the Reference_Standard_Disable
register, or if the HD_Reference_Enable bit is not set HIGH in register 82h, the
device will NOT recognize this format should it be applied to the input of the device.
The user may select VID_STD[5:0] = 1 or 3-10 ONLY as output formats.
If desired, the external VID_STD[5:0] pins may be ignored by setting bit 1 of the
Video_Control register, and the video standard may instead be selected via the
VID_STD[5:0] register of the host interface (see Section 3.10.3 on page 66).
Although the external VID_STD[5:0] pins will be ignored in this case, they should
not be left floating.
NOTE: VID_STD[5:4] should always be set LOW by the application layer since
these pins are not required to select output video standards 1 to 10.
37703 - 0 April 2006
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