The thermal tag has no wiki summary.
14
votes
3answers
1k 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 ...
7
votes
4answers
315 views
Can I create a backside “copper polygon” of the switch node in an SMPS?
I have an SMPS design that has the following properties:
9-15V input voltage
5V, 3A output
Switching frequency is 350kHz.
Switching controller is a LM25085.
The diode used is a DSSK48-003BS.
The ...
6
votes
3answers
312 views
SOT-223 Thermal Pad and Vias
I am using a LDO with a SOT-223 footprint and since it might get hot, I wanted to make a nice thermal pad under it to dissipate that heat.
I googled and I only found thermal pads, but i wanted some ...
6
votes
1answer
90 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 ...
5
votes
3answers
265 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 ...
5
votes
1answer
214 views
How to correctly apply thermal compound to ICs and heatsinks?
From http://en.wikipedia.org/wiki/Thermal_grease
All these compounds conduct heat far better than air, but far worse than metal. They are intended to fill gaps that would otherwise hold air, not ...
4
votes
2answers
59 views
Thermal relief style X or +?
Is it there any differences between a thermal relief in a 'X' shape for a '+' shape?
I am using Altium and the software has boths styles for selection.
4
votes
1answer
145 views
How does a high voltage condition break down a semiconductor?
I have TVS diode in parallel with circuitry for ESD/lightening/transient voltage protection. Say I receive an over-voltage condition which is beyond the specifications of the part, what happens ...
3
votes
4answers
858 views
Heat transfer in an airtight enclosure (component -> internal ambient -> heat sink on case?)
Are the thermal resistance values of heat sinks/etc reasonably reversible? If I wanted to dissipate an internal ambient temperature rise, could I use an internal heat sink on the enclosure wall ...
3
votes
2answers
159 views
How to calculate a PNP transistor thermal dissipation?
I am working with a dual power circuit for using USB and a LDO at the same time with a PIC18F2550. The circuit is the same as the one in the PIC's datasheet. My question is:
How do I calculate the ...
3
votes
2answers
167 views
Do Thermal Cutoff switches exist for temperatures below 50 C?
I have been trying to find some passive thermal cutoff switches for a project, but it seems that all of them are for 65 degrees C and up. Is there another name for lower temperature TCOs?
Any help ...
3
votes
1answer
399 views
How to design high-current through hole solder connection to large planes
We have a power connector, which is capable of delivering 20Amps to a PCB. On the PCB, one layer is dedicated to Vdd, which is 5V. The board is quite large, 200mmx300mm.
The power connector is ...
3
votes
1answer
158 views
LM3876 Heatsink
Could someone point me to a suitable heatsink for an LM3876 amplifier? Or, even better, a heatsink that I could attach two chips to? Perusing through Mouser's catalog was a bit overwhelming.
...
3
votes
1answer
809 views
Powering electronics with a low-cost thermoelectric generator?
When I replaced my water heater, the installer was telling me how cool the Bradford White unit I got was because the electronics are powered by the same heat used to heat the water in the tank. I ...
3
votes
1answer
318 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 ...
2
votes
1answer
331 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
...
2
votes
3answers
117 views
Do I need to use thermals on vias for reliability?
This question is further to Why thermal reliefs on vias?
I have recently been advised (by someone I consider an expert) that I should add thermal reliefs to vias which are connected to planes, even ...
1
vote
2answers
253 views
What are thermals?
I was looking through various options available for Eagle CAD through-hole and SMD pads and I noticed a "thermals" option. The documentation wasn't much help in determining their function other than ...
1
vote
2answers
115 views
What happens when I connect the GND of a LDO in a Diode to the real GND?
A friend of mine told me to put a diode between the LDO's GND pin and the circuit's GND. He said the LDO will regulate it's fixed voltage plus the diode drop. Is it true? How does it work?
I am using ...
1
vote
1answer
447 views
Are thermal fuses polarized?
I have a device with a thermal fuse in it. The fuse has failed, and I would like to replace it.
Does thermal fuse have a polarity, similar to an electrolytic capacitor, or is it the same with normal ...
1
vote
1answer
47 views
PCB Board design for H-Bridge TLE5206
I would like to make PCB board for TLE 5206-2G (check the datasheet).
It is TO263 package.
Basically, what i dont know is how to transfer heat out of the IC. I saw few PCB's that has little copper ...
0
votes
1answer
210 views
How to understand this label on part?
From the label on thermostat I can read the following, but can't decode it to understand the max current.
CAMPINI Ty 95
C1-16(3)/250~
C2-6(1)/250~
Does ...
0
votes
2answers
1k views
TO-220 case-to-sink thermal resistance
I'm using a KSC1173 TO-220 power transistor in a design, and I need to calculate the case temperature for the maximum average power dissipation, to see if the power dissipation falls under the ...
0
votes
0answers
120 views
Thermodynamics simulation for electronics
I wanted to try some thermodynamics simulation software for heat/airflow in ic enclosures. I was told that SOTA was Pro/Engineer but that didn't like my system. Will I get anywhere with Autodesk ...
