A heatsink dissipates heat into the surrounding air and thus provides cooling.
4
votes
3answers
133 views
Heatsink earthing?
I'm currently working on my first circuit that dissipates enough power that I need to use a heatsink. The component in question is a TS1085CZ33 which I'm running with a maximum load of 2.8A ...
3
votes
3answers
95 views
What material should I use to insulate my MOSFET from a heatsink?
I have a heat-sink and I want to put two FET's on it. I know I have to insulate it so the metal showing on it doesn't connect and create a path. Is there any good everyday material that would work? ...
0
votes
1answer
93 views
Altium Thermal Pad shortcircuit
All my QFN footprints are made with the Altium internal "Tools -> IPC Compliant Footprint Wizard". I get nice footprints with vias in the thermal pad.
When I try to place one of those footprints to ...
1
vote
2answers
108 views
MOSFET for PWM application
I'm designing an application where a power logic level MOSFET is driven using a 5V PWM signal at 20kHz.
The drain current will be approx. 10A and the voltage of the load 12V.
I looked into the ...
3
votes
1answer
198 views
How to avoid/reduce heat for three 1W LED's?
I'm asking on behalf of a colleague who wanted to make solar powered lighting for poor people.
Electricity generated by solar cells are stored in a car-battery sized 12V battery, and that current is ...
4
votes
1answer
183 views
Is it bad practice to install an IC to the other side of a heatsink?
Normally, we connect an IC to the other side of a heatsink than shown here:
Is it bad to place the IC on the 'unusual' side of the heatsink (and if so, why?) or are both sides each equally ...
2
votes
1answer
77 views
Mounting a heat sink on a S202S02 SSR
I'd like to mount a heat sink on a Sharp S202S02 SSR. Here's a drawing the indicates that the back surface of the device might be connected to AC:
In the "Design Guide" section of the datasheet it ...
6
votes
4answers
370 views
Validate Triac circuit
I'm designing a device to switch a heating device driven by mains power. I've done quite a lot of research and realize there's a lot of information out there but as i'm dealing with potentially deadly ...
1
vote
2answers
112 views
Help me understand triac maximum current and when to use a heatsink
Datasheets list , under Absolute Maximum Ratings
RMS on-state current = 16 A, for example.
1)How do I know if this is free air maximum current or properly heatsinked?
2)How can two triacs in ...
1
vote
3answers
252 views
Can a soapbox-sized device dissipate 10-15W of heat? If yes, how?
Some time ago, I built a soapbox-sized battery testing device. One of its functions was to discharge batteries at a specified current, and it handled most of the common battery sizes well, but its ...
2
votes
2answers
77 views
Is Rja in parallel with an external heatsink?
I have done heat sinking before, but now I'm trying to do it on SMT chips which is a bit more difficult. Anyway, I'm wondering whether the resistance between junction and ambient, Rja, is in parallel ...
6
votes
3answers
315 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 ...
3
votes
3answers
212 views
Power management for a 5V 12A load
I need to deal with a peak load at 5VDC and about 11.25A but I'm not sure how to manage this.
I have 5 individual loads of 2.25A and small loads from an MCU and some LEDs all of which should fit into ...
4
votes
1answer
154 views
Pro's and con's to using a pcb's middle layer (on a 4 layer board) as a heat sink?
I'm finishing up a PCB design and it has a surface mount (TO-252) voltage regulator. I want the regulator to dissipate heat as much as possible however it will be within its thermal limit with just ...
5
votes
4answers
424 views
how to electrically isolate a PCB from a heat sink
I have a set of LED driving lights on my motorcycle that must be wired through a ground-leg pulse width modulation dimmer. The problem is the mounting bracket for the lights is grounded, so the lamp ...
2
votes
3answers
487 views
Is this the right way to mount a 2N3055 or any TO-3 form on a heat-sink?
Top view:
Bottom view:
This is the first time I'll be using a heat-sink on a transistor. Right now these are just placed together.
Is the mounting correct?
4
votes
1answer
146 views
In a Boost Converter, where is most of the heat dissipated?
In a circuit like this:
I am for now assuming that a lot of the head will be dissipated by the Diode, and hence I am preparing the PCB to include a heat sink for it just in case. But what about the ...
4
votes
2answers
327 views
How to find a fitting cooler/heatsink for a Mosfet?
How do I find a fitting passive cooler/heatsink for a TO-220 Mosfet? What parameters do I have to search for?
3
votes
2answers
158 views
What is the material on top of the chips in this logic board, and should I leave them?
This is a very beginner-ish question. I didn't know where else to ask, or even what terms to search for, so I hope this is the right place.
I'm replacing the logic board on a monitor.
The ...
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.
...
9
votes
1answer
565 views
Why does TO-220 79xx voltage regulators conduct the input voltage to the heat sink?
I find it somewhat dangerous to connect a large heat sink on 79xx series voltage regulators. Because they transfer all the negative voltage to the heat sink. Why just they didn't make the 2nd pin of ...
2
votes
2answers
1k views
How much heat do power LEDs dissipate?
I am using this 10 W RGB LED, unfortunately DX does not provide a datasheet for it. I don't know how efficient these power LEDs are... so approximately how much applied power is converted into light ...
0
votes
2answers
118 views
how do you remove heat from a ceramic heat exchange heatsink
I have a ceramic heat exchange chip(10m x 10m). I know you are suppose to lay this on the chip, and lay a heatsink on top of that.
What is the best medium for connecting the heat exchange to the ...
3
votes
2answers
450 views
Heat Transfer of Aluminum Plate with LEDs
I'm building an LED grow light for an, um, indoor vegetable garden, and I'm trying to figure out what dimensions I can get away with for the aluminum sheeting I'm going to use for the mounting plate. ...
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 ...
3
votes
2answers
309 views
What efficient techniques exist for rectifying high voltage?
I want to rectify 120V (mains North America) at a relatively high amount of current (5 amps), so naturally my first idea is to just find a bridge rectifier. After finding one capable of the current ...
2
votes
2answers
324 views
How can I improve this SMPS design?
In: 21-32V
Out: 12V, 3A
Working Frequency: 300 KHz
Controller IC: FP5138 from Feeling Technology
MOSFET: IXTP44N100T from IXYS
Schottky Diode: MBR20100CT from ON Semi
The MOSFET and the diode ...
5
votes
1answer
215 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 ...
2
votes
2answers
252 views
Thermal adhesive for chip heat sink
I need to glue a small heat sink on top of a DIP transistors array.
At the moment I have used this adhesive:
http://uk.farnell.com/fischer-elektronik/wlk-5/adhesive-thermal-conductive/dp/1211723
I ...
2
votes
2answers
2k views
LM317 Heat sink, how big?
Thanks to the help of a few of the other guys I have my AC to DC rectifier working, and the rest of the power supply working.
Now while testing the power supply, my 18V AC transformer gets rectified ...
2
votes
2answers
224 views
Shunt resistor specifications do not contain thermal resistance data. How come?
I'm looking at the specifications of an ohmite shunt resistor: http://www.ohmite.com/catalog/pdf/10_series.pdf
It is a 0.005 ohm resistor, rated at 2,3,5 and 7 Watts (4 different parts in the same ...
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 ...
4
votes
4answers
2k views
Dissipating 1W on a TO-220 without heatsink?
Can a TO-220 without a heatsink dissipate 1W in still air?
Or, a different way of asking the question is: Assuming an ambient temperature of 25C, how can I go about calculating the maximum power I ...
2
votes
2answers
565 views
Effective MOSFET cooling
We need to drive a motor with around 40 Amps. The mosfet has an Rdson of about 7 mohms at 90 degrees Celsius. That is a whopping 11.2Watts of heat generated on the poor mosfet.
We are very space ...
3
votes
4answers
333 views
Ground as Heat Sink
First of all, this might be a newbie question, but I'm just getting into hobby electronics and robotics, so this is all very new to me. Anyways, I'm looking at the data-sheet for an L293 IC, which ...
3
votes
4answers
865 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
3answers
333 views
Regulator cooling in a confined space
I've designed a simple PWM RGB LED slow fader to be used as a garden lighting effect. My circuit works great, but I under-estimated the amount of heat that is generated by the 7805 linear regulator.
...
1
vote
1answer
137 views
Measuring temperature of microcontroller and other large ICs
I'm going to be using a microcontroller and SDRAM IC in an enclosure that could, given some environmental variables that I have no control or knowledge of, get too hot for the devices to work ...
1
vote
2answers
254 views
Where would one find thermal heat sink cases?
I am looking for a case that would work well as a heat sink. Thinking that something like a car amplifier case? Anyone know where one could find cases like this? Would be using it to house H-Bridges ...
6
votes
6answers
647 views
How do I keep PCBs cool when soldering?
I've noticed that when soldering small PCBs can get very hot. Since I haven't yet been able to find a good vise in which to hold PCBs, I mostly hold them in my hand and after several minutes of ...
5
votes
6answers
967 views
How to keep a linear regulator cool without an actual heatsink?
I want to use a linear regulator for some application, it's in a SOT-223 (not SOT-89) package. How do I keep it cool, preferably without a bulky heatsink? The regulator may be dissipating 2-3W of ...
4
votes
4answers
302 views
Low Profile Power Dissipation
I have a project where my power supplies are giving me a bit of a headache. I have three voltage regulators that I am trying to run from a single bench power supply. There are two 3.3V regulators, and ...
2
votes
2answers
5k views
How do I calculate the thermal resistance of aluminum flat stock
It's common for a lot of power circuits to bolt to a piece of aluminum flat stock. How large does the stock need to be?
Say that I'm mounting a tip122. The worst case condition is for it to have a ...
4
votes
4answers
2k views
What kind of damage could a soldering iron do to a component?
As a follow-up to this question, what kind of damage could a soldering iron do to an IC or other component if left on it for too long at too high a temperature? ESD damage can be subtle, for ...
4
votes
5answers
3k views
What is the best way to heat sink a chip when soldering it on?
I generally like to solder sockets to my boards, rather than the chip directly, but am now forced to solder the chips directly. I have several DIP and SMD components that this needs to be done with.
...
