Simulation of switching regulator

Thread Starter

EricSutton

Joined Oct 7, 2018
37
Hi,

I am trying to simulate my circuit before I order parts and am wondering how I simulate more complicated parts, such as IC's. For my case I want to simulate this switching regulator: TL2575

Please let me know how I can do this.

Also if there is a procedure to follow in general for simulating IC's.

Thanks
 

crutschow

Joined Mar 14, 2008
24,987
Typically a Spice analog simulator, such as the free LTspice from Analog Devices, is used to simulate such a circuit.
Unfortunately, TI does not appear to have a Spice model for that device. :(
 

Thread Starter

EricSutton

Joined Oct 7, 2018
37
Typically a Spice analog simulator, such as the free LTspice from Analog Devices, is used to simulate such a circuit.
Unfortunately, TI does not appear to have a Spice model for that device. :(
I see, thank you for the quick reply. Do you recommend I choose a different IC that meets the same requirements that is in the Spice database?
 

Alec_t

Joined Sep 17, 2013
11,309
Depending on the accuracy/details you need for the simulation of the rest of your circuit, can't you just assume that the TL2575 does what it says on the tin and merely puts out a fixed voltage? If so, you can model it as a simple voltage source.
A member here, @Bordodynov, can usually come up with a model for ICs. Hopefully he'll chip in.
 

eetech00

Joined Jun 8, 2013
1,905
Hi,

I am trying to simulate my circuit before I order parts and am wondering how I simulate more complicated parts, such as IC's. For my case I want to simulate this switching regulator: TL2575

Please let me know how I can do this.

Also if there is a procedure to follow in general for simulating IC's.

Thanks
Hi

If you create an account at TI you can use their “Winbench” simulator. This does a simple simulation and provides performance graphs.

You can also try to find a similar model and modify it for the desired model. But it takes some knowledge of spice to do so. You can then use the model in spice simulators like LTspice. For example, from a spice perspective, the LM2575 is very similar to the TL2575. Understanding the behavior of the target device is key to developing a model.

eT
 

Bordodynov

Joined May 20, 2015
2,606
Short spikes in current and voltage are due to the fact that the throttle has a parasitic capacitance (and it is set for the throttle of my choice), which is always there. Spikes are very short. Not every oscilloscope will show them.
 

Attachments

Last edited:

Bordodynov

Joined May 20, 2015
2,606
I've adapted the model to LTspice to make it quicker to calculate. But I didn't like the fact that the circuit works at half the 26 kHz frequency. I don't know how it works in reality. My attempts to fix the frequency to 52 kHz didn't work. I got 104 kHz. The datasheet on the diagram shows an oscillator and frequency shift control.
 

Alec_t

Joined Sep 17, 2013
11,309
Here's my first draft of a home-brew LTS model of the TL2575/LM2575. Bug reports welcome. The frequency shift and current limit are modelled, but temperature effects and voltage limits aren't.
 

Attachments

eetech00

Joined Jun 8, 2013
1,905
Hello..

Here's another "made from scratch" version.
This operates at 52Khz and the sim demo's the frequency shift during an overload.
DCM and CM are also modeled.

eT

upload_2019-6-29_8-14-41.png
 
Top