Accurate TL431 model development, analysis and evaluation

I used datasheet schematic to create a model for TL431. This is very similar to Helmut Sennewald’s approach and seems to be straight-forward way of developing model, while schematic is available and is not very complicated. However, schematic is just a starting point. Read more

Realistic SPICE model for TL431: stability, noise, impedance and performance simulation of TL431 shunt regulator

TL431 is commonly used to create a voltage reference or small linear shunt regulator. It is often considered to be a “programmable zener”. Though, there is a big difference between TL431 and a zener diode. As many of other feedback systems, TL431 can oscillate if inappropriately decoupled. Read more

RC Cut-Off Frequency & Time Constant Calculator

If you are estimating stability of feedback system, determining bandwidth or decoupling components for your circuit, RC time constant or cut-off frequency is one of essential parameters. This calculator will help you to evaluate cut-off frequency and time constant of RC circuit. Read more

Audio Total Harmonic Distortion Analyzer for LTSPICE, making THD vs. Amplitude and Frequency sweeps in LTSPICE

FFT capabilities integrated into LTSPICE simulator are nice and flexible. However, if you would like to evaluate frequency or amplitude dependence of distortions, you have to take these measurements point by point and then manually plot them.

I created an LTSPICE add-on to automate THD measurements and plot result in the form of THD vs. Amplitude and THD vs. Frequency graphs. Read more

Adventures with .MEASURE in LTSPICE

.MEASURE or .MEAS is a very convenient and one of the few options for built in post processing of simulation results in LTSPICE. Though, you should be careful, while using it. Read more

Baxandall inspired tone control – response simulation

Here is an example of parametric sweep, showing one possible way of potentiometer and variable resistor simulation in LTSPICE. I will use commonly referenced tone control, originally suggested by James and modified by Baxandall to utilize active tone control scheme. Read more

Stepping Component and Model Parameters in LTSPICE

Stepping component and model parameters is essential for many SPICE simulations. Some SPICE simulation programs are offering better capabilities than the other. Read more

Subsircuit analisys, converting subcircuit netlist to schematic

Imagine, you are lucky to get subcircuit for component you’d like to simulate. How good this subcircuit is?

Quality of simulation strongly depends on quality of subcircuit model that is used. Unfortunately, netlist for complicated subcircuit does not look like schematic drawing and is hard to interpret. Yes, everything is there, but as many design engineers, I’m thinking in terms of schematic when it is comes to necessity of interpreting functional behavior. Read more

Hierarchical Blocks in LTSPICE

LTSPICE is offering very nice possibility to incorporate repeatable portions of schematic into simulation, that is not available in many other SPICE simulation programs- hierarchical blocks. Hierarchical blocks represent reusable portions of schematic, visible on higher level of schematic as a symbol. While LTSPICE is missing multipage schematic editor, hierarchical blocks are offering another simple way of creating complex schematics. Read more

Schematic Integration of Subcircuit into LTSPICE

LTSPICE is offering very simple and straight forward way to create a symbol and  connect it to subcircuit definition.

Every subcircuit that you want to use should have corresponding schematic symbol. Symbol is a drawing, used to represent a device, described by a subcircuit or a hierarchical block. You may use existing symbol if it’s pinout and functional drawing corresponds to your subcircuit, or you may create a new drawing to represent unique subcircuit definition that you just created. Read more

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