TSH345 STMicroelectronics, TSH345 Datasheet - Page 16

• Manufacturer Part Number: TSH345
• Description: Single supply triple video buffer and selectable filter for HD and SD video applications
• Manufacturer: STMicroelectronics

Using the TSH345 to drive YC, CVBS, YUV, YPbPr and RGB video components
16/23
Figure 33. Flexibility of the TSH345 for SD and HD signals
The TSH345 is used to drive either high-definition video signals up to 30 MHz or progressive
and interlaced standard definition video signals on 75-Ω video lines. It can drive a large
panel of signals such as YC and CVBS, YUV, YPbPr and RGB, where the bottom of the
signal (the synchronization tip in the case of Y and CVBS signals) is close to zero volts. An
internal input DC value is added to the video signal in order to shift the bottom from GND.
The shift is not based on the average of the signal, but is an analog summation of a DC
component to the video signal. Therefore, no input capacitors are required, which provides a
real advantage in terms of cost and board space.
Under these conditions, it is possible to drive the signal in single supply without any
saturation of the driver against the lower rail.
Since half of the signal is lost through output impedance matching, in order to properly drive
the video line the shifted signal is multiplied by a gain of 2 or +6 dB.
HD/PV/SD
HD/PV/SD
DAC
DAC
DAC
DAC
DAC
DAC
Pb,B,C
Pr,R,C
Pb,B,C
Pr,R,C
Y,G
Y,G
(as defined in Table 4
MUX and Filter select
(as defined in Table 4
MUX and Filter select
VBS
VBS
150Ω
150Ω
150Ω
150Ω
150Ω
150Ω
150Ω
150Ω
150Ω
150Ω
150Ω
150Ω
and Table 5)
and Table 5)
NC
NC
NC
NC
NC
NC
TSH345
TSH345
TSSOP14
TSSOP14
+5V
SO14
SO14
TSH345
TSH345
TSSOP14
TSSOP14
+5V
SO14
SO14
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
RCA
Cable
Cable
Cable
Y-C-C
Y-Pb-Pr
R-G-B
Cable
Cable
Cable
SCART
VBS
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
Y-C
TV
TV
RCA
C
VBS
TSH345