K04RLM12 Datasheet, PDF (11/23 Pages) Texas Instruments – Operational Amplifier

OBSOLETE
K04RLM12, LM12CL
www.ti.com
SNOSBY8D – MAY 1999 – REVISED APRIL 2013
INPUT COMPENSATION
The LM12 is prone to low-amplitude oscillation bursts coming out of saturation if the high-frequency loop gain is
near unity. The voltage follower connection is most susceptible. This glitching can be eliminated at the expense
of small-signal bandwidth using input compensation. Input compensation can also be used in combination with
LR load isolation to improve capacitive load stability.
An example of a voltage follower with input compensation is shown here. The R₂C₂ combination across the input
works with R₁ to reduce feedback at high frequencies without greatly affecting response below 100 kHz. A lead
capacitor, C₁, improves phase margin at the unity-gain crossover frequency. Proper operation requires that the
output impedance of the circuitry driving the follower be well under 1 kΩ at frequencies up to a few hundred
kilohertz.
Extending input compensation to the integrator connection is shown here. Both the follower and this integrator
will handle 1 μF capacitive loading without LR output isolation.
CURRENT DRIVE
This circuit provides an output current proportional to the input voltage. Current drive is sometimes preferred for
servo motors because it aids in stabilizing the servo loop by reducing phase lag caused by motor inductance. In
applications requiring high output resistance, such as operational power supplies running in the current mode,
matching of the feedback resistors to 0.01% is required. Alternately, an adjustable resistor can be used for
trimming.
Copyright © 1999–2013, Texas Instruments Incorporated
Product Folder Links: K04RLM12 LM12CL
Submit Documentation Feedback
11