Datasheet
www.ti.com
GENERAL CONFIGURATIONS
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 ) sR1C1
Ǔ
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
SHUTDOWN FUNCTION
TLV2470 , , TLV2471
TLV2472 , TLV2473
TLV2474 , TLV2475 , TLV247xA
SLOS232E – JUNE 1999 – REVISED JULY 2007
APPLICATION INFORMATION (continued)
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 44 ).
Figure 44. 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 45. 2-Pole Low-Pass Sallen-Key Filter
Three members of the TLV247x family (TLV2470/3/5) have a shutdown terminal for conserving battery life in
portable applications. When the shutdown terminal is tied low, the supply current is reduced to 350nA/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 (e.g., ± 2.5V), the shutdown terminal needs to be
pulled to V
DD
– (not GND) to disable the operational amplifier.
The amplifier output with a shutdown pulse is shown in Figure 33 and Figure 34 . The amplifier is powered with a
single 5V supply and configured as a noninverting configuration with a gain of 5. The amplifier turn-on and
turn-off 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 versions are listed in the data tables.
16
Submit Documentation Feedback