max9670 Maxim Integrated Products, Inc., max9670 Datasheet - Page 24

• Manufacturer Part Number: max9670
• Description: Low-power Audio/video Switches With Audio Volume Control For Dual Scart Connectors
• Manufacturer: Maxim Integrated Products, Inc.

Low-Power Audio/Video Switch with Audio
Volume Control for Dual SCART Connectors
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
on the same SCART pin, but not at the same time. The
75Ω resistor connected to VCR_R/C_OUT must act as a
back termination resistor when the MAX9670/MAX9671
is transmitting chroma signal and as an input termina-
tion resistor when it is receiving a chroma signal. Figure
15 shows how the MAX9670/MAX9671 transmits a
Figure 15. Gain-of-2 amplifier on VCR_R/C_OUT outputs chroma signal to VCR SCART connector. Notice that the pulldown switch on
VCR_R/C_OUT is open.
Figure 16. VCR_R/C_IN receives chroma signal from VCR SCART connector. Notice that the pulldown switch on VCR_R/C_OUT is
closed and that the gain-of-2 amplifier is off. The chroma signal from VCR SCART is looped through to the TV SCART in the above
configuration.
24
______________________________________________________________________________________
0.1μF
0.1μF
VCR_R/C_IN
ENC_R/C_IN
ENC_C_IN
VCR_R/C_IN
ENC_R/C_IN
ENC_C_IN
MAX9670/MAX9671
MAX9670/MAX9671
BIAS
BIAS
BIAS
BIAS
BIAS
BIAS
LPF
LPF
LPF
LPF
chroma signal to the VCR SCART connector while
Figure 16 shows how the MAX9670/MAX9671 receives
a chroma from the VCR SCART connector.
Write a 0 into bit 2 of register 09h to open the pulldown
switch at VCR_R/C_OUT. To close the pulldown switch,
write a 0 into bit 6 of register 0Dh to turn off the output
amplifier, and then write a 1 into bit 2 of register 09h.
See Tables 17 and 18.
A
A
A
A
V
V
V
V
= 2V/V
= 2V/V
ON
OFF
= 2V/V
= 2V/V
TV_R/C_OUT
VCR_R/C_OUT
TV_R/C_OUT
VCR_R/C_OUT
75Ω
75Ω
75Ω
75Ω
SCART
SCART
VCR
TV
SCART
SCART
VCR
TV