Datasheet

  
 
 
SLOS154B− DECEMBER 1995 − REVISED JUNE 2005
23
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
single-supply operation (continued)
(b) SEPARATE BYPASSED SUPPLY RAILS (preferred)
(a) COMMON SUPPLY RAILS
Logic
−
+
Logic Logic
Power
Supply
Supply
Power
LogicLogic
−
+
Logic
OUT
OUT
Figure 39. Common Versus Separate Supply Rails
input offset voltage nulling
The TLC27L1 offers external input-offset null control. Nulling of the input-offset voltage may be achieved by
adjusting a 25-kΩ potentiometer connected between the offset null terminals with the wiper connected as shown
in Figure 40. Total nulling may not be possible.
25 kΩ
N2
V
DD
N2
N1
25 kΩ
GND
(a) SINGLE SUPPLY (b) SPLIT SUPPLY
−
+
−
+
N1
OUTOUT
IN−
IN+
IN−
IN+
Figure 40. Input Offset-Voltage Null Circuit
input characteristics
The TLC27L1 is specified with a minimum and a maximum input voltage that, if exceeded at either input, could
cause the device to malfunction. Exceeding this specified range is a common problem, especially in
single-supply operation. Note that the lower range limit includes the negative rail, while the upper range limit
is specified at V
DD
− 1 V at T
A
= 25°C and at V
DD
− 1.5 V at all other temperatures.