TLC27L2 Datasheet, PDF (26/33 Pages) Texas Instruments – LinCMOSE PRECISION DUAL OPERATIONAL AMPLIFIERS

TLC27L2, TLC27L2A, TLC27L2B, TLC27L7
LinCMOS™ PRECISION DUAL OPERATIONAL AMPLIFIERS
SLOS052B – OCTOBER 1987 – REVISED AUGUST 1994
APPLICATION INFORMATION
single-supply operation
While the TLC27L2 and TLC27L7 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 TLC27L2 and TLC27L7 permits the use of very large resistive values to
implement the voltage divider, thus minimizing power consumption.
The TLC27L2 and TLC27L7 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.
VDD
R4
R1
VI
R2
VREF
R3
C
0.01 µF
VO
+ ₎ VREF
+ ǒ Ǔ ) VO
VDD _R1 ^R3 _R3
VREF – VI
R4
R2
VREF
Figure 38. Inverting Amplifier With Voltage Reference
VO
Logic
Logic
Logic
Power
Supply
(a) COMMON SUPPLY RAILS
VO
Logic
Logic
Logic
Power
Supply
(b) SEPARATE BYPASSED SUPPLY RAILS (preferred)
Figure 39. Common Versus Separate Supply Rails
26
• POST OFFICE BOX 655303 DALLAS, TEXAS 75265