GS4901B_09 Datasheet, PDF(19/102 Page) Gennum Corporation – SD Clock and Timing Generator with GENLOCK

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GS4901B_09 Datasheet, PDF (19/102 Pages) Gennum Corporation – SD Clock and Timing Generator with GENLOCK

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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

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 67.

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 67). 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.

GS4901B/GS4900B SD Clock and Timing Generator

with GENLOCK

Data Sheet

37703 - 4

December 2009

19 of 102

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