OPA360 Datasheet, PDF (11/15 Pages) Burr-Brown (TI) – 3V Video Amplifier with 6dB Gain and Filter in SC70

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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.
OPA360
SB0S294C − DECEMBER 2003 − REVISED JULY 2004
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 12. Output Swing with 47mF on 3V Supply
Figure 13. Output Swing with 67mF on 3V Supply
V+ = 2.7V to 3.3V
Video
DAC
OPA360
2−Pole
(1)
Filter
V+
Level
Shifter
GND
Enable
OUT
C_OUT
47µF
+
R_OUT
75Ω
SAG
C_SAG
22µF
+
AC Gain = 2
DC Gain = 2.8
NOTE: (1) Optional 200Ω for use with TI’s Digital Media Processors.
Figure 14. DC-Coupled Input/AC-Coupled Output
75Ω
Television
or VCR
11