Operational Amplifier Spice Models

Introduction

National Semiconductor SPICE Macromodels are valuable design tools which mimic the response of our actual devices. These SPICE macromodel files depict typical performance at room temperature. Simulation with these models is not recommended as a replacement for, but rather as a supplement to, traditional lab testing. At higher frequencies, AC response is dominated by board layout and package parasitics. When using high speed amplifier SPICE models, National strongly suggests that topologies be verified by prototyping the circuits before designs are released to production. The part-to-part and over-temperature performance variations of the amplifiers are specified in current datasheets.

Notice

The models and information provided are believed to be reliable and correct. National assumes no responsibility for alterations, omissions, inaccuracies or designs created from these SPICE models. National also assumes no responsibility for other uses of this information, and all use of such information shall be entirely at the user's risk. National does not grant licenses or patent rights to any of the circuits described within this document.

IMPORTANT: When using LMC products Macromodels, set the option GMIN=1E-16. These devices have input currents that are much smaller than the default used in most SPICE simulators. Not setting this value correctly will result in convergence problems.

Notes:

1. Models reflect typical baseline specifications. Some performance aspects may not be modeled fully. Parameters which are modeled are listed at the beginning of most model files. The following is a typical list of modeled parameters:
   • Input offset voltage
   • Input bias current
   • Input offset current
   • Open loop frequency response including location of Poles and Zeros
   • Closed loop frequency response (where applicable)
   • Gain bandwidth product
   • AC CMRR
   • Slew rate (not including asymmetrical behavior)
   • Rise and Fall times (not including fine scale settling time)
   • Small signal input output impedance?
   • Quiescent and dynamic supply current?
   • Maximum output voltage swing
   • Output short circuit current including output current capability as a function of output voltage
   • Quiescent and dynamic supply current including load related current
   • AC PSRR
   • Voltage noise and current noise
2. Some models may have options which need to be set for the appropriate operating conditions (e.g. supply voltage, load, etc.) for more accuracy. In those cases, the information can be found at the top of the model as a comment line (e.g. See the LMH6702 model)
3. Some models may have a list comparing the datasheet parameters against the response as measured by the model. If available, this file is available for download with the model file. The model file has a .mod extension while the performance file has a .txt extension.
   • The performance files are done in all capital letters. Users should pay attention to the units and what is considered reasonable for a product. For example, , unit of current is noted as "MA" which should be read "mA" whereas unit of frequency is "MHz" and it represents "MHz." If there is any confusion as into the correct units, refer to the product datasheet.
4. While reasonable care has been given in the preparation of these models, National cannot be responsible for correct application on any and all computer systems.
5. Model users are hereby notified that these models are supplied "AS-IS," with no direct or implied responsibility on the part of National Semiconductor for their operation within a customer circuit or system. Further, National Semiconductor reserves the right to change these models without prior notice. Technical support for models will be limited to problems with the model itself.
6. In all cases, the current datasheet for a given device is the final design guideline, and is the only actual performance guarantee. For further technical information, refer to the datasheet.
7. When substitutions of current feedback op amps are made for voltage feedback op amps, results may not be acceptable. Refer to application note OA-13 for a tutorial on current feedback op amp design. Other useful application notes about Current Feedback Op-amps are:
   OA-15, OA-20, and OA-31

Individual Model Files:

You may download the models individually from the list below, or from the individual product folder for each, or you may browse through all of our available models at the bottom of this page.

Obsolete device models may be available on National’s website. However, National no longer supports obsolete device models.

Asterisks (*) below indicate a suggested alternate model for devices that do not have a dedicated model. The alternate model listed is functionally equivalent to, but not exactly specified for that particular device. For example, the model for a single device may be recommended for a dual or quad of the same device family, or a higher spec grade model listed for a lower spec grade device. Parameters such as offset voltage or supply current may need to be modified. The user must determine the suitability of the model for their application.

National’s SPICE models are provided in pure ASCII format for PCs. If using a UNIX machine, the following command maybe needed to remove the extra characters added by UNIX:
%dos2unix file1 file2
%mv file2 file1
where "%" is the UNIX prompt, “file1” is the SPICE model file downloaded from National’s website, and “file2” is the file where you want to save the SPICE model temporarily.
After executing these two commands, file1 will be the SPICE model in plain ASCII text on UNIX.

For further information regarding the use of SPICE macromodels, contact Technical Support.

* Suggested alternate model. See intro text above.