Questions tagged [thermal]

Relating to temperature rise, the flow of heat, or cooling of components

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Thermal Modeling of 0805 Thick Film Chip Resistor

I recently got confronted with the question what peak/pulse power a standard 0805 thick film resistor can withstand. Background: We are designing a 2kW bidirectional DCDC converter. The Primary side ...
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34 views

Calculating LDO thermal requirements

I've got a 5V supply, which I need to pass through an LDO to get 3.3V. The max current that the I need the LDO to support is 1A (at 3.3V). I'm looking at the TI LM3940. Using the DDPAK/TO-263 package, ...
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1answer
1k views

N-channel mosfet calculations

I am in the process of selecting a suitable FET to switch a resistive load (LEDs), triggered by a 3.3v MCU signal. The schematic would be: However, I am having some trouble with my (rough) ...
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42 views

Calculate the Thermal Resistance (Junction to ambient) from Thermal Resistance (Junction to mounting base)

I have this MOSFET - MOSFET Datasheet I want to calculate the maximum junction temperature of the MOSFET part. I have calculated the power dissipation. In the MOSFET datasheet, there is only Thermal ...
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27 views

Practical Issues with Surface Mount Heatsinks?

I'm considering using surface mount heat sinks for D2PAK devices on a PCB. These heat sinks are bent sheet metal frames with tin/lead plating in tape/reel packaging which are suitable for soldering ...
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1answer
84 views

Heat dissipation from pcb

I have a PCB with several power ic's. The pcb is connected to an aluminium plate as a heatsink on the back of the PCB. How can I measure how much heat dissipates from the top of the PCB to the air? ...
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44 views

Board is getting reset when I lower the temperature in Thermal Chamber

I have a board which I put in the thermal chamber. I increase the temperature inside the thermal chamber to 85degC. Soak it for 2 hours and note some readings. Then, when I change the temperature to ...
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34 views

lm35 Temperature Reading increasing with Hot-melt adhesive (Calculations check needed?)

I have one question with this topic: lm35 Temperature Readings are not right after sealing with Hot-melt adhesive (How mush has it Soldering max Temp toleration ?) it answered by this (Thanks from @...
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112 views

Why are there no nichrome resistor pastes?

Nichrome wire is commonly used for wire coil heating elements. Other heating elements are formed by screen printing a pattern of "resistor paste" onto a dielectric coated substrate. These pastes are ...
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99 views

How to calculate MOSFET temperature increase in PCB

I want to calculate MOSFET(DATASHEET) temperature increase for PCB. MOSFET - FDD86250_F085-D Totally 13 MOSFET's will be mounted in PCB. At the same time, maximum 8 MOSFET's will be used in PCB 1, ...
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1answer
49 views

Application based Heat sink design for Power diode

Instead of having a heatsink directly connected to the diode, I want to have a 2 mm layer of cold rolled steel in between case and heat sink(aluminium){for waterproofing as needed in the application}. ...
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22 views

Heat transfer coefficient in a Module Baseplate

Today, for example in a power IGBT module cooled by a heatsink, it has been found that the heat transfer coefficient (htc) distribution may not be uniform across the bottom surface of the module ...
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45 views

Modeling the thermal part of the Time-current curve

G’ day, I am working on designing protection devices for my research work and I am struggling to model the thermal part for the low voltage circuit breakers based on IEC standards. Based on the ...
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1answer
60 views

Macroscopic physical significance of Thermal Voltage in Diodes

Everywhere I search, the thermal voltage in diodes is described either as the microscopic property related to the average energy of electrons due to thermal motion The constant in the ideal diode ...
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42 views

Thermal Faliure of thermal overload protected ICs

I have encountered a number of instances now where ICs that supposedly include "thermal overload protection" will still heat up until they fry. Examples: LM338,LM2576. These devices datasheets ...
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1answer
76 views

Heating issues with solar charging circuit

I am using the above circuit to charge a 7.4V Li-ion Battery.With input MPPT voltage set at 12V, I have applied 13V input voltage to the circuit. The battery is charging at 1.4A. (according to the ...
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3answers
266 views

Hot-plug protection: series resistor thermal considerations

I have a circuit in place for the Linear Technology LT3502A switching regulator (datasheet here). To prevent blowing up the whole thing during hot-plugging, I have chosen to add a small parallel ...
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1answer
367 views

Help in Thermal PAD and glue calculation (equivalence) in shared heatsink

Hello if I have 15 chips to dissipate 1W each (thus 15W in total), by math calculation, which of the next three possibilities is better: 1) using a unique shared heatsink @1.7K/W with 0.5mm thermal ...
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2k views

LTSpice: How to save output from multiple .op runs

So this is a somewhat complicated question... I am trying to run a .op simulation (DC operating point), using the .step command to iterate through a bunch of component values. I would like to save the ...
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79 views

Closed enclosure thermal design the right way

I have a circuit board that works quite well (processor, screen, power supply). It has been tested successfully for an open aluminium enclosure, but now it will need to fit a rugged 100% closed box. ...
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37 views

heat generation by semiconductors

I am trying to do a power analysis of an IC. It is an I2C isolator. Now, there are 2 I2C buses (hence bidirectional). I want to analyse the effects of its working on the temperature. The ambient temp ...
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1answer
27 views

Mosfet Thermal Resistance calculation

I went through the application notes of infineon and TI. In the datasheet on the MOSFET, there is a junction to case Thermal Resistance given. Can we use these values to calculate the power ...
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8 views

What is the parameter WDIS (Package power dissipation) in the attached load switch datasheet?

Can anyone confirm what is exactly meant by WDIS? How is it different from maximum power dissipation based on thermal resistance calculation? http://www.silego.com/uploads/Products/product_499/...
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35 views

Vias direct connect better than thermal relief ? Ground/Thermal

I am thinking about if there is a positive point on having vias which have a thermal relief connection to their respective planes? I know that for soldering pads it makes sense having less copper. ...
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1answer
36 views

Thermal Simulation Software

I'm looking for a thermal simulation tool that can be used for first order viability studies. For example, I'd be interested in simulating different enclosures with given internal heat load from ...
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75 views

Component Height - Altium Designer

I'm using Altium Designer version 14.2. I am making a thermal analysis. The Analyze program expects a ODB++ format input from me. When I convert my PCB to ODB++, I can't see any height information ...
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23 views

p mosfet calculations reverse polarity for high power ( 48 V , 30 A )

i want to make reverse polarity protection for input 48 voltage , load 30 Ampere 2 dc buck converters. i was searching many solutions like diodes , but i wanna make it with p fet , so i came across ...
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46 views

How to use MLX90640 thermal camera code for a AMG8833 thermal camera?

So I want to use the AMG8833 sensor with my raspberry pi and some machine learning code, but the code was using the platypush package which is meant for the MLX90640 thermal camera. But after some ...
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57 views

How to simulate flip flop noise

Or is flip flop noisy at all? would you simluate its noise as you would do with a strong arm comparator? Why is strong arm comparator noisy but not a flip flop?
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37 views

Advice on thermoelectric generators

Hey everyone I was curious if you could help me. There maybe several questions in this so bear with me. Btw I am not an engineer so try and keep it simple please. What variables are needed to find how ...
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30 views

Thermal resistance of Thermal Interface Material

Can anyone please give information how to calculate the thermal resistance of SIL PAD "TSP A2000" from make Berguist. from The data sheet its specified thinness is 0.254mm, Thermal conductivity (W/m-...
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36 views

Junction Temperature Estimation Error

When predicting the junction temperature (Tj) of semiconductor chips (for example IGBTs) by available thermal models such as FEM simulations, how much is the maximum permissible Tj estimation error ...
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33 views

Infineon IPOSIM tool for IGBT thermal loss calculations

I used the infineon IPOSIM power tool for simulating a motor drive for my required conditions and got the results for a custom input drive cycle. The results were given as power dissipation per IGBT(...
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1answer
185 views

How to determine the right trip point of thermal cutoff for 1/4 hp 3A 115V single phase ac motor

The Thermal fuse blew in my Ryobi DP102L drill press motor, while I was drum sanding. There were no markings on the fuse. The single phase induction motor is 1/4hp 3A (no load) 1750rpm on 115V AC, ...
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3answers
226 views

Thermal resistance - Temperature transistor

I have a transistor with Vsupply = 24VDC, VCEO = 45VDC, ICE = 20mA. How to calculate the delta T (rise in temperature) of this transistor. I would like to know what thermal resistance I may have at ...
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2answers
168 views

Ways to thermally manage a small enclosure?

hopefully this is an okay place to ask this question, but anyway, I'm working on a project to measure efficiency of a mono-crystalline solar cell based off temperature in the enclosure. The solar cell ...
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48 views

Is the V_t in this document regular Thermal voltage?

I have been looking at this short document. https://pdfs.semanticscholar.org/c490/4c04a7be1d675e360409178da71a1253f6d8.pdf It uses V_t and defines it as thermal voltage of a transistor. It does not ...
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1answer
115 views

Connector current/thermal rating

This question started as a design specific question but is (now) more of a general question going forward onto other PCB product designs... For now, I am designing an I/O PCB and want to mix supply ...
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50 views

Non-uniform temperatue distribution

Please assume a semiconductor chip like IGBT or MOSFET heated by a specific power loss. It is found that the more the power loss is, the more severe the chip's temperature distribution non-uniformity ...
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57 views

Uneven chip temperature

When injecting a uniform power dissipation in a chip of IGBT power electronics modules by finite element method (FEM) in COMSOL (a good software for thermal analysis), a non-uniform temperature ...
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188 views

Can I expect a probe thermometer to still work if I cut it short?

I have a kitchen probe thermometer, a bit like this one It's overly long for my purposes, and takes an annoyingly long time to record a stable value. I assume this is because it takes a while for the ...
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1k views

Water Temperature Sensing with DHT22

This question may also be asked in physics stackexchange, but I'll try my luck first here. I want to set up a water temperature sensor system. My temperature sensor will most probably be DHT22 due to ...
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88 views

Are microprocessor pin current limits dependent on frequency?

I have blown a single pin on an Arduino Mega 2560. This is the 'step' pin of the Z axis on a 3D printer. The stepper driver is configured for 64 micro pulses per step (25600 per revolution). The ...
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3answers
75 views

Temperature raise inside a case

I'm using a D2PACK triac model ACST830-8G datasheet According to datasheet (over 1cm2 cooper) it supports 2A, considering Tamb = 43° TABLE GRAPHICS I want to use this triac inside a case and ...
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64 views

Resources for finding thermal impedances for common IC packages

I'm just looking for some extra resources for thermal impedances of JEDEC standardized packages. I've already found one such article posted by JRC, https://www.njr.com/semicon/package/thermal.html , ...