TLC27M4_15 Datasheet, PDF (33/52 Pages) Texas Instruments – PRECISION QUAD OPERATIONAL AMPLIFIERS

TLC27M4, TLC27M4A, TLC27M4B, TLC27M4Y, TLC27M9
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V_DD
V_I +
–
R1
I_P ^RP
Rp =
V_DD – V_O
I_F + I_L + I_P
V_{O IP = Pullup current required}
I_F
by the operational amplifier
(typically 500 μA)
R2
I_L R_L
SLOS093D – OCTOBER 1987 – REVISED OCTOBER 2012
C
V_O
Figure 42. Resistive Pullup to Increase V_OH
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.
Copyright © 1987–2012, Texas Instruments Incorporated
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Product Folder Links: TLC27M4 TLC27M4A TLC27M4B TLC27M4Y TLC27M9