ML6426

8

November, 1999

Pixel clock rates for the output D/A converters can be

roughly determined from the Table 1. Don’t forget that the

deflection system of a CRT display needs retrace time for

the vertical and horizontal.

This retrace time can vary from one design of an HDTV

set to another, as it only involves tradeoffs between the

frame buffer in the MPEG decoder and the CRT deflection

system. Allowing for 10% retrace time for the vertical and

20% for the horizontal, the appropriate Reconstruction

Filter is summarized in Table 2.

For VGA or RGB monitors, the following resolutions can

use the corresponding Reconstruction Filter and Video

Amplifier as shown in Table 3.

Figures 4, 5, and 6 show system diagrams when the

ML6426 provides a good solution. Figure 7 provides a

more detailed description for advanced TV applications

using various resolutions for legacy video, SDTV, and

HDTV.

640

480

VGA

60Hz

31.5kHz

25.175MHz

12.5MHz

ML6426-2

VGA

72Hz

37.9kHz

31.5MHz

15.5MHz

ML6426-3

VGA

75Hz

37.5kHz

31.5MHz

15.5MHz

ML6426-3

800

600

SVGA

56Hz

35.1kHz

36MHz

18MHz

ML6426-3

SVGA

60Hz

37.9kHz

40MHz

20MHz

ML6426-3

SVGA

72Hz

48.1kHz

50MHz

25MHz

ML6426-3

SVGA

75Hz

46.9kHz

49.5MHz

25MHz

ML6426-3

1024

768

XGA

43Hz

35.5kHz

44.9MHz

23MHz

ML6426-3

Interlaced

XGA

60Hz

37.9kHz

65MHz

33MHz

ML6426-5

XGA

70Hz

56.5kHz

75MHz

37.5MHz

ML6426-5

XGA

75Hz

60kHz

78.75MHz

39.4MHz

ML6426-6

1280

1024

SXGA

75Hz

80kHz

135MHz

68MHz

na

SXGA

60Hz

113MHz

57MHz

na

1600

1200

UXGA

60Hz

166MHz

83MHz

na

N/A = not available

Table 3: Choosing the Correct Reconstruction Filter and Video Amplifier for TV Applications, ML6426 options

USING THE ML6426 IN MULTIPLE RESOLUTIONS

Several ML6426 devices can be used in parallel to

construct a selectable filter selection block ranging from

frequencies between 6.7 MHz to 50MHz. Each ML6426

can be individually controlled via the disable pin. In a

parallel configuration, as shown in Figure 3 and 7, several

ML6426 devices can be used and selected via general

purpose I/O or other logic to perform the proper

reconstruction filtering for the resolution of choice. This

configuration allows for a minimum of bill of materials

and reduces cost. Micro Linears ML6426 EVAL Kit

demonstrates multi-resolution designs. Furthermore, since

the ML6426 pin-out is identical for all the options, the

filters can be interchanged. This allows for ease of product

migration to integrate newer resolutions to filter and drive

various DAC outputs at different sampling frequencies.