K04RLM12 Datasheet, PDF (20/23 Pages) Texas Instruments – Operational Amplifier

K04RLM12, LM12CL
OBSOLETE
SNOSBY8D – MAY 1999 – REVISED APRIL 2013
www.ti.com
Proper mounting of the IC is required to minimize the thermal drop between the package and the heat sink. The
heat sink must also have enough metal under the package to conduct heat from the center of the package
bottom to the fins without excessive temperature drop.
A thermal grease such as Wakefield type 120 or Thermalloy Thermacote should be used when mounting the
package to the heat sink. Without this compound, thermal resistance will be no better than 0.5°C/W, and
probably much worse. With the compound, thermal resistance will be 0.2°C/W or less, assuming under 0.005
inch combined flatness runout for the package and heat sink. Proper torquing of the mounting bolts is important.
Four to six inch-pounds is recommended.
Should it be necessary to isolate V− from the heat sink, an insulating washer is required. Hard washers like
berylium oxide, anodized aluminum and mica require the use of thermal compound on both faces. Two-mil mica
washers are most common, giving about 0.4°C/W interface resistance with the compound. Silicone-rubber
washers are also available. A 0.5°C/W thermal resistance is claimed without thermal compound. Experience has
shown that these rubber washers deteriorate and must be replaced should the IC be dismounted.
“Isostrate” insulating pads for four-lead TO-220 packages are available from Power Devices, Inc. Thermal grease
is not required, and the insulators should not be reused.
Definition of Terms
Input offset voltage: The absolute value of the voltage between the input terminals with the output voltage and
current at zero.
Input bias current: The absolute value of the average of the two input currents with the output voltage and
current at zero.
Input offset current: The absolute value of the difference in the two input currents with the output voltage and
current at zero.
Common-mode rejection: The ratio of the input voltage range to the change in offset voltage between the
extremes.
Supply-voltage rejection: The ratio of the specified supply-voltage change to the change in offset voltage
between the extremes.
Output saturation threshold: The output swing limit for a specified input drive beyond that required for zero
output. It is measured with respect to the supply to which the output is swinging.
Large signal voltage gain: The ratio of the output voltage swing to the differential input voltage required to
drive the output from zero to either swing limit. The output swing limit is the supply voltage less a specified
quasi-saturation voltage. A pulse of short enough duration to minimize thermal effects is used as a
measurement signal.
Thermal gradient feedback: The input offset voltage change caused by thermal gradients generated by
heating of the output transistors, but not the package. This effect is delayed by several milliseconds and
results in increased gain error below 100 Hz.
Output-current limit: The output current with a fixed output voltage and a large input overdrive. The limiting
current drops with time once the protection circuitry is activated.
Power dissipation rating: The power that can be dissipated for a specified time interval without activating the
protection circuitry. For time intervals in excess of 100 ms, dissipation capability is determined by heat
sinking of the IC package rather than by the IC itself.
Thermal resistance: The peak, junction-temperature rise, per unit of internal power dissipation, above the case
temperature as measured at the center of the package bottom. The dc thermal resistance applies when
one output transistor is operating continuously. The ac thermal resistance applies with the output
transistors conducting alternately at a high enough frequency that the peak capability of neither transistor
is exceeded.
Supply current: The current required from the power source to operate the amplifier with the output voltage
and current at zero.
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