Questions tagged [thermal]

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

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25
votes
7answers
13k views

Optimize heat sink design - connect cooling pad on PCB backside by vias

In one of my current projects I'm using an MC7805 in a D2PAK package to generate my logic supply of 5 V from an available 24 VDC supply. The current required by the circuit is 250 mA. ...
16
votes
3answers
43k views

How do filament LED bulbs work, looking very similar to incandescent bulbs?

Filament LED bulbs use very narrow strips containing the LED, which look similar to filaments of an old incandescent bulb: They look like a normal bulb with large "old-style" coal filaments, and are ...
4
votes
2answers
5k views

Thermal management of MOSFETS in TO-263 package

I'm using SUM60N02 MOSFETs in TO-263 package for my car battery charger power unit. In datasheet they have specified thermal resistance: Junction-to-Ambient - 40 °C/W when mounted on 1" square PCB ...
28
votes
4answers
18k views

How do I determine the area of copper needed on a PCB to provide adequate heatsinking for a power SMD MOSFET?

I am planning to use the IRFR5305PBF Power MOSFET (http://www.irf.com/product-info/datasheets/data/irfr5305pbf.pdf) to switch on a load. I have determined that I need an external heatsink with Rthsa &...
22
votes
8answers
7k views

How to solder a 70 °C (158 °F) thermal / temperature fuse

For my DMX project (schematics is not important), I soldered this temperature fuse which has just two leads (see picture below). The fuse doesn't work (meaning it does not conduct electricity) ... ...
5
votes
2answers
967 views

Experience with thermal glues/adhesives?

I'm planning on using a thermal adhesive to bond an LED pcb to an aluminum enclosure. The enclosure is meant to serve as a heat sink and wick away any heat generated by the LED board. The aluminum ...
2
votes
1answer
1k views

Mathematical model of the temperature of resistors/heatsinks?

I want to model the transfer function of a resistor mathematically, and am after some resources / tips on if it's possible to do so. For example, if I put 1V into a 1 Ohm resistor, I want to know how ...
0
votes
2answers
161 views

How to make a incandescent lightbulbs filament withstand shock?

I want to know, is there a way to make a tungsten lightbulbs filament withstand a mass amount of thermal shock while still producing a vast amount of heat?
12
votes
5answers
1k views

Enclosure best air flow profile

I'm in final step of a project an I need some advice about what heat evacuation profile should I use to place three fans for cooling, I have four alternatives as shown in the diagram but I don't know ...
6
votes
3answers
1k views

Apparent inconsistency of MOSFET power rating in datasheet: SOA v. max power

I am trying to use an IPP114N03L G (datasheet). I calculated the maximum power it could handle as follows: From the first two pages of the datasheet: Rthjc = 3.9K/W Tj(max) = 175C Assuming I can ...
1
vote
3answers
926 views

Electronics in high temperature environments

I'm relatively (ok, very) new to electronics. I'm trying to find where to buy parts (or even just more information on what sort of materials I should be looking for) to build a circuit board with a ...
6
votes
1answer
2k views

Generating thermal noise from a resistor

I'd like to create a random number generator based on thermal noise from a resistor, using an opamp to amplify the noise and an inverter to convert the resulting spikes into a digital signal. Here's ...
3
votes
1answer
7k views

Thermal vias in Eagle (CAD)

I'm making a part in Eagle (4.15) for a SOIC-8 package. There is a thermal pad in the center and I'm trying to add vias stitching the top and bottom pads together. In the Eagle package editor there ...
2
votes
2answers
11k views

1000 watts, 220 volt, 52" length, Coiled Nichrome wire

I need to use Nichrome wire for heating purposes. My heating temperature could be among 200 Celsius, voltage should be 220V, wattage should be approximately 1000 Watts, and length should be 52 inches ...
7
votes
1answer
565 views

How can SCRs be effectively paralleled?

I'm designing a precharge circuit which will carry 200A when closed. I'd like to use MCO150 Silicon Controlled Rectifiers, but they won't handle the current. Two in parallel looks like the most cost-...
4
votes
1answer
227 views

IC product lifetime as function of junction temperature

If an IC is rated for an absolute maximum junction temperature of say 170 Celsius, obviously it is not recommended to operate there - but how drastically is product lifetime impacted if we are close, ...
4
votes
2answers
812 views

Temperature of Solid State Relay

I would like to use a solid state relay (25A) in a 230V max. 1400W environment which will switch in 10 second intervals for a few minutes and then remain idle for hours. Will this type of switching ...
1
vote
2answers
66 views

Does this circuit adequately represent the thermal considerations for a boost converter?

I'm new to electronics, and I'm trying to use a boost converter to get 5V at 1.2A from a lithium ion battery. I've selected the TPS61232 step up converter for this solution. The datasheet has a ...
1
vote
3answers
440 views

Making Hot and Cold room at the same time with Peltier stack

I am thinking about 2 small boxes with peltier stack middle of them to get a cold room and hot room at the same time. Is it possible to get -40 degree celsius cold room and 100+ degree celsius hot ...
1
vote
0answers
26 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 @...
1
vote
1answer
2k views

Hot air soldering without destroying ICs

I have designed a circuit board that has about 20 parts on it, including a surface mount LMV431 Adjustable Zener Shunt Regulator and MMBT2907 PNP transistor. It appears that every time I solder up a ...
1
vote
2answers
2k views

Electrically conductive thermal paste

I need a thermally AND electrically conductive heat sink compound for attaching power transistors to an aluminium heat sink. I've given Coollaboratory's LiquidPro a try and that oxidized the aluminium....
0
votes
1answer
137 views

Multiple Parallel LED Drivers with Single Thermal Derating NTC Thermistor

I am looking at powering Some multi color High power LEDs e.g LED engin LZ4 or LZ7 (probably a string of five) using a tps92691 based Circuit these being high power leds it seems wise to include ...
0
votes
2answers
167 views

How do I find the output voltage of a load?

I have a load powered by a 12V source. The load can draw up to ~2A: The load has "on and off" modes, but it still draws ~40mA when in "off" mode. I want to switch the load from an MCU to save power ...