TLC27M4CPWR datasheet(33/47 Pages) TI

33 / 47 page

–

IP = Pullup current required

by the operational amplifier

(typically 500 μA)

Rp =

VDD – VO

I + IL + IP

TLC27M4, TLC27M4A, TLC27M4B, TLC27M4Y, TLC27M9

www.ti.com

SLOS093D – OCTOBER 1987 – REVISED OCTOBER 2012

Figure 42. Resistive Pullup to Increase VOH

Figure 43. Compensation for Input Capacitance

Feedback

Operational amplifier circuits nearly always employ feedback, and since feedback is the first prerequisite for

oscillation, some caution is appropriate. Most oscillation problems result from driving capacitive loads (discussed

previously) and ignoring stray input capacitance. A small-value capacitor connected in parallel with the feedback

resistor is an effective remedy (see Figure 43). The value of this capacitor is optimized empirically.

Electrostatic Discharge Protection

The TLC27M4 and TLC27M9 incorporate an internal electrostatic discharge (ESD) protection circuit that prevents

functional failures at voltages up to 2000 V as tested under MIL-STD-883C, Method 3015.2. Care should be

exercised, however, when handling these devices, as exposure to ESD may result in the degradation of the

device parametric performance. The protection circuit also causes the input bias currents to be temperature-

dependent and have the characteristics of a reverse-biased diode.

Latch-Up

Because CMOS devices are susceptible to latch-up due to their inherent parasitic thyristors, the TLC27M4 and

TLC27M9 inputs and outputs were designed to withstand —100-mA surge currents without sustaining latch-up;

however, techniques should be used to reduce the chance of latch-up whenever possible. Internal protection

diodes should not, by design, be forward biased. Applied input and output voltage should not exceed the supply

voltage by more than 300 mV. Care should be exercised when using capacitive coupling on pulse generators.

Supply transients should be shunted by the use of decoupling capacitors (0.1 µF typical) located across the

supply rails as close to the device as possible.

The current path established if latch-up occurs is usually between the positive supply rail and ground; it can be

triggered by surges on the supply lines and/or voltages on either the output or inputs that exceed the supply

voltage. Once latch-up occurs, the current flow is limited only by the impedance of the power supply and the

forward resistance of the parasitic thyristor and usually results in the destruction of the device. The chance of

latch-up occurring increases with increasing temperature and supply voltages.

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Product Folder Links: TLC27M4 TLC27M4A TLC27M4B TLC27M4Y TLC27M9

TLC27M4CPWR Datasheet(PDF) 33 Page - Texas Instruments