Rainbow Electronics MAX9671 - Manual (Page 23)

MAX9670/MAX9671
Low-Power Audio/Video Switch with Audio
Volume Control for Dual SCART Connectors
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S-Video
The MAX9670/MAX9671 support S-video from the set-
top box to the TV, set-top box to the VCR, and VCR to
the set-top box. S-video was not included in the original
SCART specifications but was added afterwards. As a
consequence, the luma (Y) signal of S-video shares the
same SCART pin as the CVBS signal. Likewise, the
chroma (C) signal shares the same SCART pin as the
red signal. The pins that can carry both CVBS and luma
have Y/CVBS in their names, and the pins that can
carry red and chroma have R/C in their names.
Now, the Y/CVBS signals are full duplex while the R/C
signals are half duplex. Therefore, S-video is limited to
being half duplex. The MAX9670/MAX9671 have to
transmit a chroma signal and receive a chroma signal
TV_SS NOT ACTIVE
VCR_SS NOT ACTIVE
TV_SS ACTIVE
VCR_SS ACTIVE
TV_SS NOT ACTIVE
VCR_SS ACTIVE
TV_SS ACTIVE
VCR_SS NOT ACTIVE
TV_SS NOT ACTIVE
VCR_SS ACTIVE
TV_SS ACTIVE
VCR_SS NOT ACTIVE
TV_SS NOT ACTIVE
VCR_SS ACTIVE
TV_SS NOT ACTIVE
VCR_SS NOT ACTIVE
TV_SS NOT ACTIVE
VCR_SS NOT ACTIVE
TV_SS ACTIVE
VCR_SS NOT ACTIVE
STATE 0
SEARCH
AUDIO: INACTIVE
VIDEO: INACTIVE
SLOW SWITCH: LISTENING FOR ACTIVITY
FAST SWITCH: INACTIVE
STATE 1
TV-TO-VCR
AUDIO: TV TO VCR
VIDEO: TV TO VCR
SLOW SWITCH: TV TO VCR
FAST SWITCH: NOT APPLICABLE
STATE 2
VCR-TO-TV
AUDIO: VCR TO TV
VIDEO: VCR TO TV
SLOW SWITCH: VCR TO TV
FAST SWITCH: VCR TO TV
TV_SS ACTIVE
VCR_SS ACTIVE
TV_SS ACTIVE
VCR_SS ACTIVE
Figure 14. Standby mode finite state machine. TV_SS is active when either 6V or 12V are present. VCR_SS is active when either 6V
or 12V are present.