Today I will leave the usual compilers and IDE’s aside, and I will take a quick look at the MPLAB Mindi™ Analog Simulator, based on the SIMetrix/SIMPLIS simulation environment, with the added benefit of proprietary model files from Microchip. Thus, in addition to generic circuit devices, one can to use those proprietary models to simulate many Microchip analog components.
At the core of MPLAB Mindi™ lies SIMPLIS (SIMulation of Piecewise LInear Systems), a circuit simulator designed to handle the simulation challenges of switching power systems. Similarly to SPICE (Simulation Program with Integrated Circuit Emphasis), SIMPLIS works at the component level but is 10 to 50 times faster. For switching power systems, the piecewise linear (PWL) in SIMPLIS can provide superior convergence behavior compared to SPICE.
Before going into the particularities of MPLAB Mindi, it’s worth noting here that there’s also a free version SIMetrix/SIMPLIS Elements which one can use without license or copying restrictions, for personal, educational and business use. The SIMetrix/SIMPLIS Elements comes with all the features of the full version, but the size of the circuit that can be simulated is limited. However, those limits are generous enough for them to be used for real work, especially when it comes to the simulation of simple circuits – such as the case of many student projects.
Same as the SIMetrix/SIMPLIS Elements, MPLAB Mindi is also free, but it comes with the added functionality provided by the pre-installed proprietary model files from Microchip. There are over 300 model libraries, covering a wide range of Microchip products: Operational Amplifiers, Instrumentation Amplifiers, Active Filter Circuits, MOSFET and Motor Drivers, PWM and non-PWM Power Controllers, Power Modules, LED Drivers, Switching Regulators, Generic switch, and passive components. One should know that to download MPLAB Mindi you need to have a Microchip account and to accept the terms and conditions of MPLAB Mindi.
In Mplab Mindi you can find a wide range of possible applications, such as:
- Generate BODE responses for active and passive filter systems.
- Evaluate transient responses to a wide variety of input conditions.
- Generate closed-loop stability responses for control systems, including switch mode power supplies and motor drive applications.
- Verify slew rates and drive strengths through power drive or signal conditioning chains.
- Model noise effects in signal conditioning or control systems.
Transient analysis: a virtual workbench
In today’s blog post I will focus only on transient analysis, which resembles the method of bench testing a circuit. In the transient analysis, one simulates the behavior of the circuit over a specified period and saves all the results – i.e., all the voltages and currents in the circuit – to the hard disk. After the simulation is complete, one can then randomly probe the circuit to look at any voltage, current or device power over the analysis time frame. Fixed probes can be placed on the circuit before running the analysis, and the corresponding waveform at that point of the circuit will be automatically displayed.
In a way, it’s just like probing your circuit with an oscilloscope, but with some added benefits. For example, here you have access to current probes – good ones are obscenely expensive in real life. With MPLAB Mindi it takes only a few clicks to probe current flow through your circuit – just think on probing the current through an inductor.
There are some differences between real life testing and simulation. One is that the simulation works for a specified time only. If you want to make changes to your circuit, you have to make those changes and then re-run the simulation. The second big difference is that nothing could go wrong in the simulation. You can see if the current or the voltage go beyond the maximum limits of a specific component – without releasing the magic smoke.