Datasheet

TLV2760, TLV2761, TLV2762, TLV2763, TLV2764, TLV2765
FAMILY OF 1.8 V MICROPOWER RAIL-TO-RAIL INPUT/OUTPUT
OPERATIONAL AMPLIFIERS WITH SHUTDOWN
SLOS326F − JUNE 2000 − REVISED AUGUST 2013
15
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
general configurations (continued)
V
I
V
O
C1
+
−
R
G
R
F
R1
f
–3dB
+
1
2pR1C1
V
O
V
I
+ ǒ1 )
R
F
R
G
Ǔ
ǒ
1
1 ) 2pfR1C1
Ǔ
V
DD
/2
Figure 33. Single-Pole Low-Pass Filter
If even more attenuation is needed, a multiple pole filter is required. The Sallen-Key filter can be used for this
task. For best results, the amplifier should have a bandwidth that is 8 to 10 times the filter frequency bandwidth.
Failure to do this can result in phase shift of the amplifier.
V
I
C2
R2R1
C1
R
F
R
G
R1 = R2 = R
C1 = C2 = C
Q = Peaking Factor
(Butterworth Q = 0.707)
(
=
1
Q
2 −
)
R
G
R
F
_
+
f
–3dB
+
1
2pRC
V
DD
/2
Figure 34. 2-Pole Low-Pass Sallen-Key Filter
circuit layout considerations
To achieve the levels of high performance of the TLV276x, follow proper printed-circuit board design techniques.
A general set of guidelines is given in the following.
D Ground planes—It is highly recommended that a ground plane be used on the board to provide all
components with a low inductive ground connection. However, in the areas of the amplifier inputs and
output, the ground plane can be removed to minimize the stray capacitance.
D Proper power supply decoupling—Use a 6.8-μF tantalum capacitor in parallel with a 0.1-μF ceramic
capacitor on each supply terminal. It may be possible to share the tantalum among several amplifiers
depending on the application, but a 0.1-μF ceramic capacitor should always be used on the supply terminal
of every amplifier. In addition, the 0.1-μF capacitor should be placed as close as possible to the supply
terminal. As this distance increases, the inductance in the connecting trace makes the capacitor less
effective. The designer should strive for distances of less than 0.1 inches between the device power
terminals and the ceramic capacitors.