Datasheet

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SB0S294E − DECEMBER 2003 − REVISED SEPTEMBER 2006
www.ti.com
11
SUPPLY VOLTAGE vs COUPLING CAPACITOR
The output voltage swing is a function of the coupling
capacitor value. The value of the sag correction capacitor
has only a minor influence. The smaller the coupling
capacitor, the greater the output swing. Therefore, to
accommodate the large signal swing with very small
coupling capacitors (22µF and 33µF), a higher supply
voltage might be needed.
Figure 12. Output Swing with 47mF on 3V Supply
As seen in Figure 7, the output swing with a 33µF coupling
capacitor is already very close to the saturation limit on a
3V supply. Over time and temperature, a capacitor might
change its value slightly, which in turn could force the
output into saturation. Using the 50Hz, 1/2 blackĊ1/2
white screen test signal as a worst-case analysis,
Figure 12 and Figure 13 demonstrate that a 3V supply
could be used with a coupling capacitor as low as 47µF.
Figure 13. Output Swing with 67mF on 3V Supply
C
OUT
47
µ
F
R
OUT
75
GND
75
+
+
OUT
Enable
2−Pole
Filter
(1)
SAG
C
SAG
22
µ
F
AC Gain = 2
DC Gain = 2.8
Television
or VCR
OPA360
Video
DAC
NOTE: (1) Optional 200
for use with TI’s Digital Media Processors.
Level
Shifter
V+
V+ = 2.7V to 3.3V
ENABLE
Figure 14. DC-Coupled Input/AC-Coupled Output