Rainbow Electronics MAX9595 - Manual (Page 10)

MAX9595
Audio/Video Switch for Dual SCART Connector
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Pin Description (continued)
PIN NAME FUNCTION
32 TV_G_OUT TV SCART Green Video Output. Internally biased at 1V.
33 TV_B_OUT TV SCART Blue Video Output. Internally biased at 1V.
34 VCR_Y/CVBS_OUT VCR SCART Luma/Composite Video Output. Internally biased at 1V.
35 VCR_R/C_OUT
VCR SCART Red/Chroma Video Output. Internally biased at 1V for red video signals and 2.2V
for chroma video signal.
37 TV_R/C_IN
TV SCART Red/Chroma Video Input. Internally biased at 1V for red video signals, or 2.2V for
chroma video signals.
38 TV_Y/CVBS_IN TV SCART Luma/Composite Video Input. Internally biased at 1.2V.
39 VCR_Y/CVBS_IN VCR SCART Luma/Composite Video Input. Internally biased at 1.2V.
40 VCR_R/C_IN
VCR SCART Red/Chroma Video Input. Internally biased at 1.2V for red video signals and 1.9V
for chroma video signals.
41 VCR_G_IN VCR SCART Green Video Input. Internally biased at 1.2V.
42 VCR_B_IN VCR SCART Blue Video Input. Internally biased at 1.2V.
43 ENC_Y/CVBS_IN Digital Encoder Luma/Composite Video Input. Internally biased at 1.2V.
44 ENC_R/C_IN
Digital Encoder Red/Chroma Video Input. Internally biased at 1.2V for red video signals, or 1.9V
for chroma video signals.
45 ENC_G_IN Digital Encoder Green Video Input. Internally biased at 1.2V.
46 ENC_B_IN Digital Encoder Blue Video Input. Internally biased at 1.2V.
47 ENC_Y_IN Digital Encoder Luma Video Input. Internally biased at 1.2V.
48 ENC_C_IN Digital Encoder Chroma Video Input. Internally biased at 1.9V.
EP GNDAUD
Exposed Paddle. Solder to the circuit board ground (GNDAUD) for proper thermal and electrical
performance.
Detailed Description
The MAX9595 is a switch matrix that routes audio and
video signals between different ports using the I
2 C
interface. The ports consist of the MPEG decoder out-
put, and two SCART connectors for the TV and VCR.
Per EN50049 and IEC 933, the encoder can only input
a signal to the SCART connector, while TV and VCR
SCART connectors are bidirectional.
The MAX9595 circuitry consists of four major sections:
the video section, the audio section, the slow- and fast-
switching section, and the digital interface.
The video section consists of clamp and bias circuitry,
input buffers, reconstruction filters, a switch matrix, a
Y/C mixer, and output buffers. All video inputs are AC-
coupled through a 0.1µF capacitor to set an acceptable
DC level using clamp or bias networks. The bidirection-
al red/chroma outputs can be connected to ground
using I 2 C control to make them terminations when
red/chroma is an input (see the Video Inputs section).
The audio section features an input buffer, a switching
matrix, volume- or gain-control circuitry, and output dri-
vers. The audio inputs are AC-coupled through a 0.1µF
capacitor. The TV output audio path has volume control
from -56dB to +6dB in 2dB steps, while the VCR output
audio path has volume control from -6dB to +6dB in
6dB steps. The MAX9595 can be configured to switch
inputs during a zero-crossing function to reduce clicks.
The slow-switching feature allows for bidirectional, tri-
level, slow-switching input and output signals at pin
VCR_SS and TV_SS, respectively. The slow-switching
signals from the VCR set the aspect ratio or video source
of the TV screen. If INTERRUPT_OUT is enabled, then
INTERRUPT_OUT changes to a high-impedance state if
any of the slow-switching inputs change logic levels. See
the Slow Switching section.