TLC27M4CPWR datasheet(32/48 Pages) TI

32 / 48 page

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 = 170 pF, RL = NO LOAD

TLC27M4, TLC27M4A, TLC27M4B, TLC27M4Y, TLC27M9

SLOS093D – OCTOBER 1987 – REVISED OCTOBER 2012

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Output Characteristics

The output stage of the TLC27M4 and TLC27M9 is designed to sink and source relatively high amounts of

current (see typical characteristics). If the output is subjected to a short-circuit condition, this high current

capability can cause device damage under certain conditions. Output current capability increases with supply

voltage.

All operating characteristics of the TLC27M4 and TLC27M9 were measured using a 20-pF load. The devices

drive higher capacitive loads; however, as output load capacitance increases, the resulting response pole occurs

at lower frequencies, thereby causing ringing, peaking, or even oscillation (see Figure 41). In many cases,

adding a small amount of resistance in series with the load capacitance alleviates the problem.

Figure 41. Effect of Capacitive Loads and Test Circuit

Although the TLC27M4 and TLC27M9 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.

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Product Folder Links: TLC27M4 TLC27M4A TLC27M4B TLC27M4Y TLC27M9

TLC27M4CPWR 数据表(PDF) 32 Page - Texas Instruments