Texas Instruments THS7375EVM Evaluation Module THS7375EVM THS7375EVM 데이터 시트
제품 코드
THS7375EVM
75 W
Y'/G' Out
CVBS/Sync
CVBS
+1.8 V
R
DaVinci
DMxxxx
Y'/G'
R
P' /B'
B
R
P' /R'
R
R
1
2
3
4
5
6
7
14
13
12
11
10
9
8
CH1 OUT
CH2 OUT
CH3 OUT
CH4 OUT
V
S+
BYPASS
NC
CH1 IN
CH2 IN
CH3 IN
CH4 IN
GND
DISABLE
NC
THS7375
To GPIO Controller
or GND
75 W
75 W
P' /B' Out
B
75 W
75 W
P' /R' Out
R
75 W
75 W
75 W
+3 V to +5 V
SBOS449A – SEPTEMBER 2008 – REVISED JANUARY 2011
www.ti.com
fluctuates depending on the video content. Because
swing and an increase in power dissipation of the
the corner frequency of the input is a very low 2.5 Hz,
THS7375. While the THS7375 was designed to
the corner frequency of the input is also a very low
operate with a junction temperature of up to +125°C,
2.5 Hz, which is respectable performance relative to a
care must be taken to ensure that the junction
STC configuration.
temperature does not exceed this level; otherwise,
long-term
long-term
reliability
could
suffer.
Although
this
configuration only adds less than 10 mW of power
OUTPUT MODE OF OPERATION:
dissipation
per
channel,
the
overall
low-power
DC-COUPLED
dissipation
of
the
THS7375
design
minimizes
The THS7375 incorporates a rail-to-rail output stage
potential thermal issues even when using the TSSOP
that can be used to drive the line directly without the
package at high ambient temperatures.
need for large ac coupling capacitors, as shown in
Note that the THS7375 can drive the line with dc
. This approach offers the best line tilt and
coupling regardless of the input mode of operation.
field tilt (or droop) performance because no ac
The only requirement is to make sure the video line
coupling occurs. Keep in mind that if the input is
has
proper
termination
in
series
with
the
ac-coupled, then the resulting tilt because of the input
output—typically 75-
Ω
. This termination helps isolate
ac coupling is seen on the output regardless of the
capacitive loading effects from the THS7375 output.
output coupling. The 80-mA output current drive
Failure to isolate capacitive loads may result in
capability of the THS7375 was designed to drive two
instabilities with the output buffer, potentially causing
video lines simultaneously (essentially, a 75-
Ω
load)
ringing
or
oscillations
to
appear.
The
stray
while maintaining as wide an output dynamic range
capacitance appearing directly at the THS7375 output
as possible.
pins should be kept below 22-pF. The best way to
One concern of dc coupling, however, arises if the
ensure this limit is maintained is to place the 75-
Ω
line is terminated to ground. If the ac-bias input
series output resistor as close as possible to the
configuration is used, the output of the THS7375 has
output pin. If an output capacitor is used, as
a dc bias on the output. With two lines terminated to
discussed in the next section, then it should be
ground, this configuration creates a dc current path
placed after the resistor.
that results in a slightly decreased high output voltage
Figure 52. Typical SDTV System with DC-Coupled Line Driving
24
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