TLC272CPWR datasheet(31/51 Pages) TI

31 / 51 page

TLC272, TLC272A, TLC272B, TLC272Y, TLC277

LinCMOS

 PRECISION DUAL OPERATIONAL AMPLIFIERS

SLOS091E – OCTOBER 1987 – REVISED FEBRUARY 2002

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

output characteristics (continued)

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

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

– 2.5 V

2.5 V

TA = 25°C

f = 1 kHz

VIPP = 1 V

(d) TEST CIRCUIT

Figure 41. Effect of Capacitive Loads and Test Circuit

Although the TLC272 and TLC277 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 operational amplifier 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.

TLC272CPWR 数据表(PDF) 31 Page - Texas Instruments