Reference & Information
Guideline for Derating Operational Amplifiers
This page provides a guide-line for Voltage and Temperature derating of Operational Amplifiers.
The table uses a derating factor, or Correction Factor which is basically a parameter reduction.
The derating factor is a percent reduction in a parameter, with a derating of 1.0 being no reduction at all.
Even though a component is rated to a particular maximum temperature, derating will insure a worst-case design.
So that some unpredictable event, operating condition or design uncertainty does not cause a component to over-heat.
However even without derating an integrated circuit is normally specified below its maximum temp, because of part-to-part variations.
So there is always some head room, but the concern is about reliability and good design practices.
Derating is a sound design practice because it lowers the junction temperature of the device increasing component life, and reliability.
Op Amp Derating Guidelines:
Op Amp Correction Factor
| Parameters |
Operational
or
Differential
Amplifiers |
Comparators |
Sense
Amplifiers |
Current
Amplifiers |
Voltage
Regulators |
Analog
Switches |
Absolute maximum
supply voltage |
0.80 |
0.90 |
0.80 |
0.80 |
N/A |
0.90 |
| Power dissipation |
0.75 |
0.75 |
0.75 |
0.75 |
0.80 |
0.80 |
| AC Input Voltage |
1.00 |
1.00 |
1.00 |
1.00 |
N/A |
N/A |
| Output Voltage |
1.00 |
N/A |
N/A |
1.00 |
N/A |
N/A |
Output Voltage
Open Drain |
N/A |
0.90 |
0.90 |
N/A |
N/A |
N/A |
Output Current
AC/DC |
0.80 |
Current Max
Short-Circuit |
0.90 |
N/A |
Maximum
Junction Temperature |
100oC |
| Manufacturers |
Op Amps |
Comparators |
Op Amps |
Regulators |
Switches |
The table rows provide the different type of operational amplifier
configurations, while the columns give the recommended derating from 100
percent of operation.
The term used is Derating Factor or Stress Ratio to describe the amount to derate the device parameter.
Note that the amount of derating applies to any temperature of operation, even room temperature.
However, the junction temperature is held to a maximum of 1000C. The numbers provided are recommendations to increase or insure reliable operation.
Increasing Air flow [Manufacturers of Fans] or attaching a Heat sink [Manufacturers of Heat sinks] are two methods
that can be used to increase the operational parameters at high ambient temperatures. Most data sheets use 25oC for device parameters.
Op Amp equivalent Circuit |
Most operational parameters are provided for a temperature of 25oC, with a maximum permissible junction temperature.
Normally a 'parameter' per degree C is also provided to indicate how much to reduce a parameter with increasing temperature to keep the junction temperature below the maximum allowable figure.
The table is a general guideline for Op Amps; however, the package style selected will define the absolute operating environment.
Also attaching a heat sink if applicable or applying forced air will greatly reduce the requirement to derate a device, or at least allow the device to operate at a higher temperature.
Main section, How To Derate Electronic Components, or Digital IC Derating.
|
Analog Temperature Sensors:
LM50
SOT-23 Single-Supply Centigrade Temperature Sensor.
(+10 mV/C) and has a DC offset of +500 mV.
LM62
2.7V, 15.6 mV/C SOT-23 Temperature Sensor
VO = (+15.6 mV/C x T) + 480 mV
LM135A - Precision Temperature Sensor
TO-92, TO-46, 8-pin SOIC
Related section
Op Amp Parasitic Compensation
Thermal Overload Protect; Some ICs such as voltage regulators contain protection circuits which shut down circuit operation in the event that an over-voltage or over-temperature condition occurs.
Thermal Regulation of a voltage regulator for example is defined as the percent change of Volts Out [Vout] per watt, within 10mS after the input is stepped.
How to derate operational amplifiers based on temperature, Op Amp Over-Heating, Over Heat Op Amps
Modified 6/13/15
© 1998 - 2016 All rights reserved Larry Davis
