TLC27M2CPWR datasheet(29/49 Pages) TI

29 / 49 page

TLC27M2, TLC27M2A, TLC27M2B, TLC27M7

LinCMOS PRECISION DUAL OPERATIONAL AMPLIFIERS

SLOS051E − OCTOBER 1987 − REVISED AUGUST 2008

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

2.5 V

− 2.5 V

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

(b) CL = 170 pF, RL = NO LOAD

(d) TEST CIRCUIT

TA = 25°C

f = 1 kHz

VI(PP) = 1 V

Figure 41. Effect of Capacitive Loads and Test Circuit

output characteristics (continued)

Although the TLC27M2 and TLC27M7 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.

TLC27M2CPWR 数据表(PDF) 29 Page - Texas Instruments