TSH343 STMicroelectronics, TSH343 Datasheet - Page 11

• Manufacturer Part Number: TSH343
• Description: 280MHz single-supply triple video buffer
• Manufacturer: STMicroelectronics

Specifications of TSH343

• Bandwidth: 280MHz
• Slew Rate: 780V/μs

TSH343
Figure 27. Detailed view of one TSH343 channel
Because of the shape of the signal shown in
high-speed buffer. The TSH343 supplied in 5V single power supply, features a low output rail
of 40mV on 150-ohm load. The TSH343 is used to drive high definition video signals up to
30MHz on 75-ohm video lines. It is dedicated to driving YPbPr signals where the
synchronization tip—close to zero volt—is included in the Y signal.
Figure 27
STi7200 where the DAC output is loaded by 140Ω and the bottom of the synchronization tip
is set at 10mV. Using the TSH343, an internal input DC value of 600mV is added to the
video signal in order to shift the bottom from 10mV to 610mV. 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.
The internal gain of 2 obtained makes it possible to remove two resistors on the BOM. To
avoid any perturbation on matching from the DACs output impedance along a large band of
30MHz in HD, a discrete reconstruction filtering is implemented after the driver. This filter is
matched on 75-ohms. Note that the TSH343 cannot be AC output coupled (it cannot sink an
output current, therefore it is not possible to implement an output series capacitor).
DAC
shows a solution used on the STMicroelectronics reference design of STi7100 or
140Ω
10mV
1,01V
5Volt
0Volt
600mV
DC
-5V
+
+5V
1/3 TSH343
(gain=2)
0V
3,22V
1,22V
5Volt
0Volt
Figure
75Ω
(10mV+600mV)*gain
68pF
25, we use a very low output rail triple
470nH
STB
68pF
video line
Application information
610mV
TV
1,61V
75Ω
0Volt
5Volt
11/17