TLE2021 datasheet(54/66 Pages) TI

54 / 66 page

TLE202x, TLE202xA, TLE202xB, TLE202xY

EXCALIBUR HIGH-SPEED LOW-POWER PRECISION

OPERATIONAL AMPLIFIERS

SLOS191 – FEBRUARY 1997

POST OFFICE BOX 655303

• DALLAS, TEXAS 75265

APPLICATION INFORMATION

voltage-follower applications

The TLE202x circuitry includes input-protection diodes to limit the voltage across the input transistors; however,

no provision is made in the circuit to limit the current if these diodes are forward biased. This condition can occur

when the device is operated in the voltage-follower configuration and driven with a fast, large-signal pulse. It

is recommended that a feedback resistor be used to limit the current to a maximum of 1 mA to prevent

degradation of the device. This feedback resistor forms a pole with the input capacitance of the device. For

feedback resistor values greater than 10 k

Ω, this pole degrades the amplifier phase margin. This problem can

be alleviated by adding a capacitor (20 pF to 50 pF) in parallel with the feedback resistor (see Figure 71).

CF = 20 pF to 50 pF

IF ≤ 1 mA

VCC +

VCC –

–

Figure 71. Voltage Follower

Input offset voltage nulling

The TLE202x series offers external null pins that further reduce the input offset voltage. The circuit in

Figure 72 can be connected as shown if this feature is desired. When external nulling is not needed, the null

pins may be left disconnected.

1 k

Ω

GND (single supply)

VCC – (split supply)

5 k

Ω

OFFSET N2

OFFSET N1

IN –

IN +

Figure 72. Input Offset Voltage Null Circuit

TLE2021 Arkusz danych(PDF) 54 Page - Texas Instruments