TLC271A datasheet(40/51 Pages) DIODES

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TLC271, TLC271A, TLC271B

Document number: DS35395 Rev. 2 - 2

40 of 51

www.diodes.com

November 2014

TLC271, TLC271A, TLC271B

Application Information

Bias select feature

The TLC271 offers a bias-select feature that allows the user to select any one of three bias levels depending on the level of performance

desired. The trade-off between bias levels relates to ac performance and power dissipation as below.

Typical values TA = +25°C, VDD = 5V

Mode

Units

High bias

RL =10kΩ

Medium bias

RL =100kΩ

Low bias

RL =1MΩ

Power Dissipation

3.4

0.5

0.05

Slew Rate

3.6

0.4

0.03

V/µs

Equivalent Input Noise Voltage at f=1kHz

nV√Hz

Unity Gain Bandwidth

1.7

0.5

0.09

MHz

ɸm

Phase Margin

46°

40°

34°



AVD

Large Signal Differential Voltage Amplification

170

480

V/mV

Bias selection

Bias selection is achieved by connecting the bias select pin to one of three voltage levels (see below). For medium-bias applications, it is

recommended that the bias select pin be connected to the midpoint between the supply rails. This procedure is simple in split-supply

applications, since this point is ground.

In single-supply applications, the medium-bias mode necessitates using a voltage divider as indicated below. The use of large-value

resistors in the voltage divider reduces the current drain of the divider from the supply line. However, large-value resistors used in

conjunction with a large-value capacitor require significant time to charge the supply to the midpoint after the supply is switched on. A

voltage other than the midpoint can be used if it is within the voltages specified table.

To the Bias

Select Pin

Low

Medium

High

1 M

0.01 µF

VDD

1 M

Bias Mode

Bias Select Voltage

(Single Supply)

Low

VDD

Medium

1 V to VDD -1 V

High

GND

Figure 91

High-Bias Mode

In high-bias mode, the TLC271 series features low offset voltage drift, high input impedance and low noise. Speed in this mode approaches

that of BiFET devices but at only a fraction of the power dissipation. Unity-gain bandwidth is typically greater than 1 MHz.

Medium-Bias Mode

The TLC271 in medium-bias mode features low offset voltage drift, high input impedance and low noise. Speed in this mode is similar to

general-purpose bipolar devices, but power dissipation is only a fraction of that consumed by bipolar devices.

Low-Bias Mode

In low-bias mode, the TLC271 features low offset voltage drift, high input impedance, extremely low power consumption and high differential

voltage gain.

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