TLE2662 Datasheet, PDF (27/40 Pages) Texas Instruments – DUAL uPOWER JFET-INPUT OPERATIONAL AMPLIFIER WITH SWITCHED-CAPACITOR VOLTAGE CONVERTER

TLE2662
DUAL µPOWER JFET-INPUT OPERATIONAL AMPLIFIER
WITH SWITCHED-CAPACITOR VOLTAGE CONVERTER
SLOS118B – DECEMBER 1992 – REVISED AUGUST 1994
APPLICATION INFORMATION
typical application (continued)
VOL+ 80
VOL+ 60
VOL+ 40
VOL+ 20
VOL
VOL– 20
RIPPLE AND SWITCHING NOISE ON
AMPLIFIER OUTPUT
vs
TIME
VCC+ = 5 V
RL = 600 Ω
CIN = 100 µF
COUT = 10 µF
VID = –100 mV
VOL+ 20
VOL+ 15
VOL+ 10
RIPPLE AND SWITCHING NOISE ON
AMPLIFIER OUTPUT
vs
TIME
VCC+ = 5 V
RL = 600 Ω
CIN = 100 µF
COUT = 100 µF
VID = –100 mV
VOL+ 5
VOL
VOL– 5
VOL– 40
VOL– 10
VOL– 60
VOL– 15
VOL– 80
0
10 20 30 40 50 60 70 80 90 100
t – Time – µs
Figure 51
VOL– 20
0
10 20 30 40 50 60 70 80 90 100
t – Time – µs
Figure 52
Additional filtering can be added between SCOUT and V_{CC –} to further reduce ripple and noise. For example,
adding the simple low-pass LC filter shown in Figure 53, implemented using a 50-µH inductor and 220-µF
capacitor (available in surface mount), results in the reduced levels of ripple and switching noise at the
amplifier’s outputs (see Figures 54 and 55). Larger values of L or C can be used for even better attenuation.
SCOUT
LH
VCC
COUT
+
0.1 µF
CF
Filter
1
fr =
2 π LC
Figure 53. LC Filter Used to Reduce Ripple and Switching Noise, f_r = 1/2π√LC, A = – 40 dB Per Decade
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