TLV172IDCKT.B datasheet(18/49 Pages) TI2

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100p

200p

300p

400p

500p

Capacitive Load (F)

RO = 25

RO = 50

C013

OUT = 0

OUT = 25

OUT = 50

RI = 1 k

VIN = 100mV

+ 18 V

± 18 V

RF = 1 k

ROUT

100p

200p

300p

400p

500p

Capacitive Load (F)

RO = 25

RO = 50

C013

OUT= 0

OUT= 25

OUT= 50

VIN = 100mV

+ 18 V

± 18 V

ROUT

TLV172, TLV2172, TLV4172

SBOS784C – NOVEMBER 2016 – REVISED JANUARY 2019

www.ti.com

Product Folder Links: TLV172 TLV2172 TLV4172

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Feature Description (continued)

If there is any uncertainty about the ability of the supply to absorb this current, add external Zener diodes to the

supply pins; see Figure 26. Select the Zener voltage so that the diode does not turn on during normal operation.

However, the Zener voltage must be low enough so that the Zener diode conducts if the supply pin begins to rise

above the safe-operating, supply-voltage level.

The input pins of the TLVx172 are protected from excessive differential voltage with back-to-back diodes; see

Figure 26. In most circuit applications, the input protection circuitry has no effect. However, in low-gain or G = 1

circuits, fast-ramping input signals can forward-bias these diodes because the output of the amplifier cannot

respond rapidly enough to the input ramp. If the input signal is fast enough to create this forward-bias condition,

then limit the input signal current to 10 mA or less. If the input signal current is not inherently limited, an input

series resistor can limit the input signal current. This input series resistor degrades the low-noise performance of

the TLVx172. Figure 26 shows an example configuration that implements a current-limiting feedback resistor.

8.3.4 Capacitive Load and Stability

The dynamic characteristics of the TLVx172 are optimized for common 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 (for example, ROUT equal to 50 Ω) in series with the output.

Figure 27 and Figure 28 show graphs of small-signal overshoot versus capacitive load for several values of

ROUT. See the Feedback Plots Define Op Amp AC Performance application note for details of analysis

techniques and application circuits.

100-mV output step, G = –1

Figure 27. Small-Signal Overshoot vs Capacitive Load

100-mV output step, G = 1

Figure 28. Small-Signal Overshoot vs Capacitive Load

TLV172IDCKT.B Datasheet(PDF) 18 Page - Texas Instruments

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