TLC2652_17 Datasheet, PDF (21/41 Pages) Texas Instruments – Advanced LinCMOSE PRECISION CHOPPER-STABILIZED OPERATIONAL AMPLIFIERS

TLC2652, TLC2652A, TLC2652Y
Advanced LinCMOS PRECISION CHOPPERĆSTABILIZED
OPERATIONAL AMPLIFIERS
SLOS019E − SEPTEMBER 1988 − REVISED FEBRUARY 2005
TYPICAL CHARACTERISTICS^†
PHASE MARGIN
vs
FREE-AIR TEMPERATURE
50°
48°
46°
44°
PHASE MARGIN
vs
LOAD CAPACITANCE
60°
VDD _± = ± 5 V
RL = 10 kΩ
50°
TA = 25°C
40°
30°
20°
42°
VDD _± = ± 5 V
RL = 10 kΩ
CL = 100 pF
40°
−75 −50 −25 0
25 50
75 100 125
TA − Free-Air Temperature − °C
Figure 31
10°
0°
0
200
400
600
800
CL − Load Capacitance − pF
Figure 32
1000
† _{Data at high and low temperatures are applicable only within the rated operating free-air temperature ranges of the various devices.}
APPLICATION INFORMATION
capacitor selection and placement
The two important factors to consider when selecting external capacitors C_XA and C_XB are leakage and
dielectric absorption. Both factors can cause system degradation, negating the performance advantages
realized by using the TLC2652.
Degradation from capacitor leakage becomes more apparent with the increasing temperatures. Low-leakage
capacitors and standoffs are recommended for operation at T_A = 125°C. In addition, guard bands are
recommended around the capacitor connections on both sides of the printed circuit board to alleviate problems
caused by surface leakage on circuit boards.
Capacitors with high dielectric absorption tend to take several seconds to settle upon application of power, which
directly affects input offset voltage. In applications where fast settling of input offset voltage is needed, it is
recommended that high-quality film capacitors, such as mylar, polystyrene, or polypropylene, be used. In other
applications, however, a ceramic or other low-grade capacitor can suffice.
Unlike many choppers available today, the TLC2652 is designed to function with values of C_XA and C_XB in the
range of 0.1 µF to 1 µF without degradation to input offset voltage or input noise voltage. These capacitors
should be located as close as possible to the C_XA and C_XB pins and returned to either V_{DD −} or C RETURN. On
many choppers, connecting these capacitors to V_{DD −} causes degradation in noise performance. This problem
is eliminated on the TLC2652.
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