TLC274 datasheet(32/42 Pages) TI

32 / 42 page

TLC274, TLC274A, TLC274B, TLC274Y, TLC279

LinCMOS

™ PRECISION QUAD OPERATIONAL AMPLIFIERS

SLOS092C – SEPTEMBER 1987 – REVISED MARCH 1998

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

output characteristics (continued)

2.5 V

– 2.5 V

(d) TEST CIRCUIT

TA = 25°C

f = 1 kHz

VIPP = 1 V

(a) CL = 20 pF, RL = NO LOAD

(b) CL = 130 pF, RL = NO LOAD

Figure 41. Effect of Capacitive Loads and Test Circuit

Although the TLC274 and TLC279 possess excellent high-level output voltage and current capability, methods

for boosting this capability are available, if needed. The simplest method involves the use of a pullup resistor

(RP) connected from the output to the positive supply rail (see Figure 42). There are two disadvantages to the

use of this circuit. First, the NMOS pulldown transistor N4 (see equivalent schematic) must sink a comparatively

large amount of current. In this circuit, N4 behaves like a linear resistor with an on-resistance between

approximately 60

Ω and 180 Ω, depending on how hard the op amp input is driven. With very low values of RP,

a voltage offset from 0 V at the output occurs. Second, pullup resistor RP acts as a drain load to N4 and the gain

of the operational amplifier is reduced at output voltage levels where N5 is not supplying the output current.

TLC274 Datasheet(PDF) 32 Page - Texas Instruments