Datasheet

V
I
C2
R2R1
C1
R
R
F
G
R1 = R2 = R
C1 = C2 = C
Q = Peaking Factor
(Butterworth Q = 0.707)
_
+
R
G
R
2
F
–
Q
f
–3dB
1
1
2p
RC
=
=
V
V
I
O
C1
+
R R
R1
G F
f
–3dB
1
2pR1C1
1
(1 )( )
1 1 1
O F
I G
V R
V R sR C
= +
+
=
TLV2460-Q1, TLV2461-Q1, TLV2462-Q1, TLV2463-Q1, TLV2464-Q1
TLV2460A-Q1, TLV2461A-Q1, TLV2462A-Q1, TLV2463A-Q1, TLV2464A-Q1
SGLS008E –MARCH 2003–REVISED OCTOBER 2012 www.ti.com
General Configurations
When receiving low-level signals, limiting the bandwidth of the incoming signals into the system is often required.
The simplest way to accomplish this is to place an RC filter at the noninverting terminal of the amplifier (see
Figure 51).
Figure 51. 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 eight to ten times the filter frequency
bandwidth. Failure to do this can result in phase shift of the amplifier.
Figure 52. 2-Pole Low-Pass Sallen-Key Filter
Shutdown Function
Two members of the TLV246x-Q1 family (TLV2460-Q1 and TLV2463-Q1) have a shutdown terminal for
conserving battery life in portable applications. When the shutdown terminal is tied low, the supply current is
reduced to 0.3 μA/channel, the amplifier is disabled, and the outputs are placed in a high-impedance mode. To
enable the amplifier, the shutdown terminal can either be left floating or pulled high. When the shutdown terminal
is left floating, care should be taken to ensure that parasitic leakage current at the shutdown terminal does not
inadvertently place the operational amplifier into shutdown. The shutdown terminal threshold is always
referenced to V
DD
/ 2. Therefore, when operating the device with split supply voltages (for example, ±2.5 V), the
shutdown terminal must be pulled to V
DD
− (not GND) to disable the operational amplifier.
The amplifier’s output with a shutdown pulse is shown in Figure 22, Figure 23, Figure 24, and Figure 25. The
amplifier is powered with a single 5-V supply and configured as a noninverting configuration with a gain of 5. The
amplifier turnon and turnoff times are measured from the 50% point of the shutdown pulse to the 50% point of
the output waveform. The times for the single, dual, and quad are listed in the data tables.
Circuit Layout Considerations
To achieve the levels of high performance of the TLV246x-Q1, follow proper printed-circuit board design
techniques. A general set of guidelines is given in the following.
• 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.
22 Submit Documentation Feedback Copyright © 2003–2012, Texas Instruments Incorporated
Product Folder Links: TLV2460-Q1 TLV2461-Q1 TLV2462-Q1 TLV2463-Q1 TLV2464-Q1 TLV2460A-Q1 TLV2461A-
Q1 TLV2462A-Q1 TLV2463A-Q1 TLV2464A-Q1