OPA202IDBVT datasheet(19/47 Pages) TI1

19 / 47 page

250

2500

25000

Capacitive Load (pF)

G = -1, RISO = 0

G = -1, RISO = 25

G = -1, RISO = 50

G = +1, RISO = 0

G = +1, RISO = 25

G = +1, RISO = 50

C004

OPA202, OPA2202, OPA4202

www.ti.com

SBOS812E – OCTOBER 2017 – REVISED FEBRUARY 2020

Product Folder Links: OPA202 OPA2202 OPA4202

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7.3 Feature Description

7.3.1 Capacitive Load and Stability

The dynamic characteristics of the OPAx202 are optimized for commonly encountered gains, loads, and

operating conditions. The OPAx202 feature a patented output stage capable of driving large capacitive loads. In

a unity-gain configuration, the series is capable of directly driving to 25 nF of pure capacitive load. Increase the

gain to enhance the ability of the devices to drive greater capacitive loads. The particular op amp circuit

configuration, layout, gain, and output loading are some of the factors to consider when establishing whether an

amplifier is stable in operation.

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. Add a small resistor (ROUT equal to 50 Ω, for example) in series with the output to achieve isolation.

Figure 40 shows the effects on small-signal overshoot for several capacitive loads and combinations of isolation

resistance. See the Feedback Plots Define Op Amp AC Performance application bulletin for details of analysis

techniques and application circuits, available for download from the www.TI.com. By using isolation resistors,

driving capacitive loads of 100 nF and beyond is possible.

Figure 40. Small-Signal Overshoot vs Capacitive Load (10-mV Output Step)

OPA202IDBVT Datasheet(PDF) 19 Page - Texas Instruments