Datasheet
TLC272, TLC272A, TLC272B, TLC272Y, TLC277
LinCMOS PRECISION DUAL OPERATIONAL AMPLIFIERS
SLOS091E – OCTOBER 1987 – REVISED FEBRUARY 2002
29
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
single-supply operation
While the TLC272 and TLC277 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 TLC272 and TLC277 permits the use of very large resistive values to implement
the voltage divider, thus minimizing power consumption.
The TLC272 and TLC277 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.
–
+
C
0.01 µF
R3
V
REF
V
I
R1
R2
V
DD
V
O
R4
V
REF
+ V
DD
R3
R1 ) R3
V
O
+ (V
REF
* V
I
)
R4
R2
) V
REF
Figure 38. Inverting Amplifier With Voltage Reference
(b) SEPARATE BYPASSED SUPPLY RAILS (preferred)
(a) COMMON SUPPLY RAILS
–
+
–
+
Logic Logic Logic
Power
Supply
Supply
Power
LogicLogicLogic
OUT
OUT
Figure 39. Common vs Separate Supply Rails