TLC274 Datasheet, PDF (30/42 Pages) Texas Instruments – LinCMOSE PRECISION QUAD OPERATIONAL AMPLIFIERS

TLC274, TLC274A, TLC274B, TLC274Y, TLC279
LinCMOS™ PRECISION QUAD OPERATIONAL AMPLIFIERS
SLOS092C – SEPTEMBER 1987 – REVISED MARCH 1998
APPLICATION INFORMATION
single-supply operation
While the TLC274 and TLC279 perform well using dual power supplies (also called balanced or split supplies),
the design is optimized for single-supply operation. This design includes an input common-mode voltage range
that encompasses ground as well as an output voltage range that pulls down to ground. The supply voltage
range extends down to 3 V (C-suffix types), thus allowing operation with supply levels commonly available for
TTL and HCMOS; however, for maximum dynamic range, 16-V single-supply operation is recommended.
Many single-supply applications require that a voltage be applied to one input to establish a reference level that
is above ground. A resistive voltage divider is usually sufficient to establish this reference level (see Figure 38).
The low input bias current of the TLC274 and TLC279 permits the use of very large resistive values to implement
the voltage divider, thus minimizing power consumption.
The TLC274 and TLC279 work well in conjunction with digital logic; however, when powering both linear devices
and digital logic from the same power supply, the following precautions are recommended:
1. Power the linear devices from separate bypassed supply lines (see Figure 39); otherwise the linear
device supply rails can fluctuate due to voltage drops caused by high switching currents in the digital
logic.
2. Use proper bypass techniques to reduce the probability of noise-induced errors. Single capacitive
decoupling is often adequate; however, high-frequency applications may require R_C decoupling.
VDD
R1
R2
VI
R4
VO
VREF
R3 ^C
0.01 µF
VREF = VDD
R3
R1 + R3
VO
=
(VREF –
VI )
R4
R2
+
VREF
Figure 38. Inverting Amplifier With Voltage Reference
Power
VO
Logic
Logic
Logic
Supply
(a) COMMON SUPPLY RAILS
VO
Logic
Logic
Logic
Power
Supply
(b) SEPARATE BYPASSED SUPPLY RAILS (preferred)
Figure 39. Common Versus Separate Supply Rails
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