OPA1644AIPWR datasheet(22/50 Pages) TI2

22 / 50 page

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Frequency (Hz)

C005

10 k

5 VRMS

OPA164x Amplifier

Traditional JFET-Input Amplifier

4.5

5.5

6.5

7.5

±10

±8

±6

±4

±2

Common-Mode Voltage (V)

C004

OPA164x Family

Traditional JFET-Input Amplifier

OPA1641, OPA1642, OPA1644

SBOS484D – DECEMBER 2009 – REVISED APRIL 2016

www.ti.com

Product Folder Links: OPA1641 OPA1642 OPA1644

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Figure 36. Input Capacitance of the OPA164x Family of Amplifiers Compared to Traditional JFET-input

Amplifiers

By stabilizing the input capacitance, the distortion performance of the amplifier is greatly improved for

noninverting configurations with high source impedances. The measured performance of an OPA164x amplifier

is compared to a traditional JFET-input amplifier in Figure 37. The unity-gain configuration, high source

impedance, and large-signal amplitude produce additional distortion in the traditional amplifier.

Figure 37. Measured THD+N of the OPA164x Family of Amplifiers Compared to Traditional JFET-input

Amplifiers

8.1.5 Capacitive Load and Stability

The dynamic characteristics of the OPA164x are optimized for commonly encountered gains, loads, and

operating conditions. The combination of low closed-loop gain and high capacitive loads decreases the phase

margin of the amplifier and can lead to gain peaking or oscillations. As a result, heavier capacitive loads must be

isolated from the output. The simplest way to achieve this isolation is to add a small resistor (ROUT equal to 50 Ω,

for example) in series with the output.

Figure 19 and Figure 20 illustrate graphs of Small-Signal Overshoot vs Capacitive Load for several values of

ROUT. Also, see Applications Bulletin AB-028, Feedback Plots Define Op Amp AC Performance (SBOA015)

available for download at www.ti.com for details of analysis techniques and application circuits.

8.1.6 Power Dissipation and Thermal Protection

The OPA164x series of operational amplifiers are capable of driving 2-k

Ω loads with power-supply voltages of up

to ±18 V over the specified temperature range. In a single-supply configuration, where the load is connected to

the negative supply voltage, the minimum load resistance is 2.8 k

Ω at a supply voltage of 36 V. For lower supply

voltages (either single-supply or symmetrical supplies), a lower load resistance can be used, as long as the

output current does not exceed 13 mA; otherwise, the device short-circuit current protection circuit can activate.

OPA1644AIPWR Datasheet(PDF) 22 Page - Texas Instruments

OPA1644AIPWR Datasheet(HTML) 22 Page - Texas Instruments

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