In version 4.9.4, when I try to make a new Thermal Package Description, I encounter and error and cannot save it. The error is as shown below. The error says "Device name Device does not match the name filter of any device in the thermal package description. But the thing is there is no device named Device anymore because I renamed them to something else.
The only time I can save is when the (one and only) device is called “Device*(xxxx)”. But of course this is not useful because I want to name my device something else.
Happens also in version 4.8.9.
But does not happen when I try a previous version (4.7.5).
Or maybe I am missing something?
I am running Standalone, on Windows 11.
The error message occurs due to incomplete device naming. In the “Device Types” tab, you have defined “MOSFET*” and “Diode*” as placeholders, where the asterisk represents any number (e.g., MOSFET1 and MOSFET2 both using the thermal description for MOSFET*).
However, you need to define the exact devices in the “Thermal Impedance” tab. Based on the error message, it seems that the default 2x2 matrix still contains “Device” and “Device1.” Since these do not match your specified device types, the error occurs when you attempt to save the thermal package description.
Hi @RetoChristen,
Thank you for your reply. I confirmed that if I add descriptions into the Thermal Impedance window then the problem is solved. But I am curious, I downloaded models from On Semiconductor (available publicly), and in their SiC MOSFET Thermal Package Description, they did not have to add any devices into the Thermal Impedance matrix. How were they able to save their model in the beginning? Plus I can still save their model if I make changes to it, while the Thermal Impedance Matrix is still empty.
Is the reason because they totally deleted any device in the Thermal Impedance Matrix thus there is no conflict anymore.
By default, a Thermal Package Description uses an Impedance Matrix, which must be at least a 1×1 matrix if only one device is present in the package. However, you can also model thermal coupling using a State-Space Matrix by clicking the highlighted button.
In a State-Space Matrix, you can either specify the exact number of devices, ensuring the device names match those you have defined, or set the value to 0, as shown in the Onsemi example or the example below.
If you set the value to 0, there will be no thermal coupling between the devices. Instead, the
Thermal Chain from the
Device Type will connect directly to the heat sink.
This approach is useful for modules containing multiple devices with no significant thermal coupling, either because it is not relevant or due to a lack of measured data.
I hope this answers your question.
Hi again @RetoChristen ,
I understand your explanation. Then let me ask you: how would I know if there are Thermal dependencies between multiple devices if only looking at datasheet that is provided by the vendor? I don’t believe such information is typically provided in datasheet. Only a single Thermal Chain is provided.
Then in such case, if we set Thermal Matrix = 0, do I just use the same Thermal Chain provided in datasheet for all the devices within the package?
For example, let’s say there is some Module containing 1 MOSFET for High Side, and 1 Diode for low side. The datasheet only shows 1 Thermal Chain. When I make the Thermal Package Description for this, I will have to make 2 separate devices, but since datasheet only contains 1 Thermal Chain network, I use that for both?
Thank you for your advice in advanced.
Hi @ghariman
This is a great question, but one best directed to the semiconductor vendors. We provide a tool that enables modeling these effects, but we are not responsible for the input data.
I highly recommend reaching out to the vendor for more details. They typically have access to far more data than what is publicly available in their datasheets.
