TLC27M4_15 Datasheet, PDF (30/52 Pages) Texas Instruments – PRECISION QUAD OPERATIONAL AMPLIFIERS

TLC27M4, TLC27M4A, TLC27M4B, TLC27M4Y, TLC27M9
SLOS093D – OCTOBER 1987 – REVISED OCTOBER 2012
APPLICATION INFORMATION
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Single-Supply Operation
While the TLC27M4 and TLC27M9 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 TLC27M4 and TLC27M9 permits the use of very large resistive values to
implement the voltage divider, thus minimizing power consumption.
The TLC27M4 and TLC27M9 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 RC decoupling.
V_DD
R1
R2
V_I
R4
V_O
V_REF
R3 ^C
0.01 μF
V_REF = V_DD
R3
R1 + R3
V_O = (V_REF – V_I)
R4
R2
+
V_REF
Figure 38. Inverting Amplifier With Voltage Reference
Output
Logic
Logic
Logic
(a) COMMON SUPPLY RAILS
Power
Supply
Output
Logic
Logic
Logic
Power
Supply
(b) SEPARATE BYPASSED SUPPLY RAILS (preferred)
Figure 39. Common Versus Separate Supply Rails
30
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