Rainbow Electronics MAX4399 - Manual (Page 10)

MAX4399
Detailed Description
The MAX4399 audio/video switch matrix connects audio
and video signals between different ports. In the case of
a set-top box, the ports consist of the MPEG decoder
and three SCART connectors. For DVD+RW recorders
and some televisions, the ports consist of the main
board, front panel, tuner, and two SCART connectors.
The video section consists of input buffers, a crosspoint
switch, and output drivers that can be disabled. There
is also a mixer, which creates a composite video signal
from S-video. The video inputs can be set in either
clamp or bias mode. The red/chroma outputs have pull-
downs that connect the outputs to video ground as
described in the Video Inputs section.
The audio section features input buffers, a crosspoint
switch, and output drivers. The TV audio path has vol-
ume control from -56dB to +6dB in 2dB steps. The VCR
and AUX audio paths have volume control from -6dB to
+6dB in 6dB steps. The MAX4399 can be configured to
switch inputs during a zero crossing to reduce clicks.
The MAX4399 can also switch volume levels during a
zero crossing to reduce zipper noise. The audio out-
puts can operate in different modes. For instance, left
and right audio channels can be swapped (see the
Audio Outputs section).
The MAX4399 has two fast-switching inputs and one
fast-switching output. Fast switching is used for creat-
ing on-screen displays by switching between the CVBS
and RGB signals. Under I
2 C-compatible control, the
fast-switching output can follow either of the fast-
switching inputs or be set high or low.
The MAX4399 features three slow-switching input/out-
puts to support slow switching, which sets the screen
aspect ratio or video source of the display device. The
slow switching relies on tri-level logic in which the levels
are 0V, 6V, and 12V. The status of the slow-switching
input is continuously read and stored in register 0Eh. If
INTERRUPT_OUT is enabled, then INTERRUPT_OUT
changes to a high-impedance state if any of the slow-
switching inputs change logic levels. The slow-switching
outputs can be set to a logic level or high impedance by
writing to registers 07h, 09h, or 0Bh.
The MAX4399 can be configured through an I 2 C-com-
patible interface. DEV_ADDR sets the I 2 C-compatible
address.
SCART Video Switching
The MAX4399 triple SCART audio/video switch
includes multiplexed video amplifiers and a Y-C mixer-
driver with a trap filter to drive an RF modulator. The
MAX4399 switches video from an MPEG decoder out-
put and TV, VCR, and AUX SCART connectors.
Audio/Video Switch for Three SCART
Connectors
10 ______________________________________________________________________________________
Pin Description (continued)
PIN NAME FUNCTION
53 TV_Y/CVBS_IN TV SCART Luma/Composite Video Input. Internally biased at 1.22V.
54 AUX_R/C_IN AUX SCART Red/Chroma Video Input. Internally biased at 1.22V for red, or 1.8V for chroma.
55 AUX_Y/CVBS_IN AUX SCART Luma/Composite Video. Internally biased at 1.22V.
56 VCR_Y/CVBS_IN VCR SCART Luma/Composite Video Input. Internally biased at 1.22V.
57 VCR_FS_IN VCR SCART Fast-Switching Input
58 VCR_R/C_IN VCR SCART Red/Chroma Video Input. Internally biased at 1.22V for red, or 1.8V for chroma.
59 VCR_G_IN VCR SCART Green Video Input. Internally biased at 1.22V.
60 VCR_B_IN VCR SCART Blue Video Input. Internally biased at 1.22V.
62 ENC_Y/CVBS_IN Digital Encoder Luma/Composite Video Input. Internally biased at 1.22V.
63 ENC_R/C_IN
Digital Encoder Red/Chroma Video Input. Internally biased at 1.22V for red, or 1.8V for
chroma.
64 ENC_G_IN Digital Encoder Green Video Input. Internally biased at 1.22V.
65 ENC_B_IN Digital Encoder Blue Video Input. Internally biased at 1.22V.
66 ENC_Y_IN Digital Encoder Luma Video Input. Internally biased at 1.22V.
67 ENC_C_IN Digital Encoder Chroma Video Input. Internally biased at 1.8V.
68 ENC_FS_IN Digital Encoder Fast-Switching Input