TLC082-Q1 Datasheet, PDF (18/31 Pages) Texas Instruments – WIDE-BANDWIDTH HIGH-OUTPUT-DRIVE SINGLE-SUPPLY OPERATIONAL AMPLIFIERS

TLC080-Q1, TLC081-Q1
TLC082-Q1, TLC083-Q1
TLC084-Q1, TLC085-Q1
SLOS510B – SEPTEMBER 2006 – REVISED MAY 2011
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 52).
R_G
R_F
V_I
R1
−
+
V_O
C1
f–3dB
+
1
2pR1C1
ǒ Ǔǒ Ǔ ^VO
VI
+
1
)
RF
RG
1
1 ) sR1C1
Figure 52. 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.
C1
V_I
R1
+
R2
_
C2
R_F
R_G
R1 = R2 = R
C1 = C2 = C
Q = Peaking Factor
(Butterworth Q = 0.707)
f–3dB
+
1
2pRC
( ) ^{RG =}
R_F
1
2−
Q
Figure 53. 2-Pole Low-Pass Sallen-Key Filter
Shutdown Function
Three members of the TLC08x family (TLC080/3/5) have a shutdown (SHDN) terminal for conserving battery life
in portable applications. When SHDN is tied low, the supply current is reduced to 125 μA/channel, the amplifier is
disabled, and the outputs are placed in a high-impedance mode. To enable the amplifier, SHDN can either be left
floating or pulled high. When SHDN is left floating, care should be taken to ensure that parasitic leakage current
at SHDN does not inadvertently place the operational amplifier into shutdown. SHDN threshold is always
referenced to the voltage on the GND terminal of the device. Therefore, when operating the device with split
supply voltages (e.g. ±2.5 V), SHDN needs to be pulled to V_DD– (not system ground) to disable the operational
amplifier.
The amplifier’s output with a shutdown pulse is shown in Figure 45 and Figure 46. The amplifier is powered with
a single 5-V supply and is configured as noninverting 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 are listed in the data tables.
Figure 39 through Figure 42 show the amplifier’s forward and reverse isolation in shutdown. The operational
amplifier is configured as a voltage follower (A_V = 1). The isolation performance is plotted across frequency using
0.1-V_PP, 2.5-V_PP, and 5-V_PP input signals at ±2.5-V supplies and 0.1-V_PP, 8-V_PP, and 12-V_PP input signals at ±6-V
supplies.
18
Copyright © 2006–2011, Texas Instruments Incorporated