Questions tagged [thermal]

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

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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
65 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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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 ...
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119 views

install heatsink on BJT

I am facing the problem with the heat of transistor disturb sensor reading. Here the link refer problem I am using BC548 transistor. It is a bit hot when operating because it disipates power around ...
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2answers
275 views

Shot or thermal noise of a MOS transistor

I'm trying to compare the shot and thermal noise contributions in a MOS transistor. In the literature, the above-threshold MOS transistor has only thermal noise, which is found by integrating the ...
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1answer
154 views

Control board powered up with reverse polarity. power transistor blown. Is this repairable? [closed]

My dog chewed through the power cord. I 'repaired' it not paying attention to polarity. It was a 2A, 9V wall wart type power supply. The motherboard is from an elliptical exercise machine. The one ...
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2answers
165 views

Wha't the difference to use the junction to case thermal resistance instead of the junction to lead thermal resitance?

In case I have a diode, and I want to know it could dissipate the power, I have two values, but I can't choose between them: - Junction to ambient thermal resitance \$R_{ja}\$ - Junction to lead ...
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3answers
758 views

How do electrons carry thermal energy in Peltier coolers?

I've read that when electrons enter from metal to semiconductor type N, they gain thermal energy and make that side cooler and the reverse happens when they leave semiconductor to the conductor. Why ...
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2answers
48 views

Am I misunderstanding steady state power disspation calculations?

I am looking at the Littlefuse 5KP series. It says on the datasheet: I am trying to understand how they arrive at \$P_D\$ = 8.0W. Given thermal resistances of 40°C/W or 8.0°C/W, and 100°C ...
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2answers
219 views

Where would Iceo flow through and would it cause thermal runaway?

I was reading this page about thermal run away. And it mentions: Due to increase in the temperature of collector junction, Ico will increase, Vbe will decrease. But for Ico to increase Ic and ...
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4answers
205 views

MOSFET thermal resistance

I am trying to calculate the total thermal resistance of my FET to see what heat sinks are required, are the following calculations correct? $$ Power = \frac{T_{jmax} - T_a}{\theta_{JC} + \theta_{CA}}...
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30 views

Low power thermal actuator/radiator head

There are a lot of thermal thermostats like this one that work on batteries. I searched for an actuator that is working with ~5V but I only find 24V / 220V . I can only find full systems that work ...
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1answer
113 views

Name of fabric insulator found inside motors

What is the name of the fabric sleeve insulator used for components (typically fuses) and solder joints found inside motor windings? Can regular heat shrink tubing be used as a substitute? Image by ...
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612 views

Can a thermal fuse of a higher rated current be used safely?

I want to replace a 115°C 250V 2A thermal fuse used in a fan motor. The only fuses available locally are 115°C 277V 15A. Can I use the higher current rated thermal fuse? Since it is a thermal fuse, I ...
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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, ...
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75 views

May I use a smaller wattage resistor as mosfet's gate driver for a very short time?

In a H-Bridge circuit, i am using gate resistors on all the mosfets. My calculations for one of them, Gate voltage 4.5 V and Resistor 100 ohm gives me 45 mA, means 203 mW. In a pulse of 16 us i ...
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1answer
40 views

Thermal hysteresis of shunt regulator

What is the meaning of the "Thermal hysteresis" in shunt regulator datasheet ? Will it contribute to output tolerance ? FYI: It's TL4050C50-Q1 datasheet.
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Why do 0 dB attenuators exist?

I am reading this paper : Upgrade of a low-temperature scanning tunneling microscope for electron-spin resonance and found that for thermalization, they use 0 dB attenuators. Page 6: Having the ...
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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) ... ...
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4answers
172 views

BLDC Motor Performance at high altitude?

How does a BLDC motor performance change at high altitude where the air density is really low? For example, say I have a given BLDC motor with given torque-RPM performance curves. Now, I assume these ...
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2answers
60 views

Collisions of Thermal Impedances

As shown in the picture below, thermal impedances of an IGBT device depends on the temperature. However, there is a strange phenomenon as follows. While with increasing the temperature, steady-state ...
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1answer
46 views

Do thermal cutoffs exist that would work with a line that is 40-75V 0.5A and a max temp of ~85°C?

I have a bunch of COB LEDs that I am going to wire in series using an LED driver. The driver gives off between 40-75V and 0.5A max. The circuit should run around 70V and 0.5A. Due to space ...
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1answer
116 views

Light source that withstands extreme conditions [closed]

I am designing an aircraft obstruction light, and Federal Aviation Administration (FAA) requires crazy requirements for their standards. One standard goes as following (From FAA AC 150/5345-43H): 4....
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3answers
250 views

thermal fuse as electrical fuse

I am trying to understand the spec of a Datasheet of a thermal fuse. for example the one below : https://nl.farnell.com/panasonic-electronic-components/eyp2bn134/fuse-thermal-cut-off-2a/dp/1832031 ...
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1answer
291 views

Waterproofing MLX90640 far infrared thermal sensor

I would like to use the MLX90640 far infrared thermal sensor array on a car as a "night vision" camera. Since glass blocks thermal radiation I have to install it outside the cabin. Is it possible to ...
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1answer
358 views

PCB power supply layout considerations

I'm designing a circuit that steps down 230v AC to 12v DC and then uses an MCP73213 IC to charge a 7.4v li-po battery. There is also functionality to switch over to the battery supply if there is no ...
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3answers
657 views

How to calculate Junction to Ambient temperature of LED?

I'm trying to calculate the Junction to Ambient temperature for this Cree LED: https://www.mouser.ca/datasheet/2/90/ds--XHP502-1093532.pdf I know how to calculate this: Junction Temp = Junction to ...
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5answers
982 views

How hot should wires get?

I am using 10 AWG wire to power a BLDC motor, and these wires can get quite hot. When an IC is intended for high power uses, it is common practice to put a heat sink on it, but what about for wires? ...
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4answers
1k views

Replace a one shot thermal fuse with a resetting one [closed]

My mother owns a device for drying fruits and stuff. Now every year or so, the thermal fuse breaks. I'm always checking if the fan is damages or something else, but the device is always fine. It is ...
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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 ...
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1answer
94 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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2answers
402 views

Thermal pad thickness

We are going to use GAP PAD HC 5.0 thermal pad to transfer the heat from a FPGA (XCKU040) to a heatsink. My question is regarding the thickness I should choose to obtain best performance. On the one ...
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1answer
342 views

Galvanic Corrosion of Copper, Aluminum, and ENIG Plating

I need to attach a heat sink to a PCB. The PCB is a 560 mm x 9 mm strip of LEDs. The LEDs vary from mid-power to high power. I have a pure copper solution for the high power. I am investigating the ...
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3answers
110 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
126 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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3answers
1k views

OP1678 running hot

I have built a circuit that converts a 0-5 V signal to a +/- 9 volt signal using OPA1678 Op-Amps (original design from Here). The 0-5V signal is received from a 10k potentiometer across the +5V and ...
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2answers
714 views

Use Thermal Relief in High Current Traces?

I'm designing a SMPS PCB with a pretty high current goal (using it to power multiple servos). Using KiCAD, I decided to use solid fills on the pads of the high current areas, but by default thermal ...
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1answer
53 views

Is thermally conductive epoxy needed if long settling time is acceptable?

I'm using SMD based analog temperature measuremet ICs (a version of the old TMP36). It will be mounted on a tiny and thin (.5mm) PCB I've cut to hold the IC and a few mfgr recommended parts and a 3 ...
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2answers
71 views

Thermal parameters for the LM1117

Looking at the datasheet for the LM1117 regulator, on page 18 to 20 there's a table of various layouts for copper cooling planes for the LM1117 in SOT-223 and TO-252 packages. Comparing figures 30 and ...
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1answer
96 views

Compact thermostat for VCO temperature stability

So I have a voltage controlled oscillator with an exponential input made using the THAT2181 VCA IC. The schematic is shown below - the THAT2181 IC is used to change the C4 capacitor charging current ...
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38 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
61 views

LM 56 temperature trip point resistor selection

I'm having a hard time grasping on how to calculate the values for resistors R1 R2 and R3 in the typical application diagram pg.2 in the data sheet. Could some one break down the calculation steps ...
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4answers
4k views

Is there a way to define 26mV thermal voltage with simple words [closed]

This 26mV thermal voltage at room temperature is used in non-linear diode equation. I tried to learn about it to see what it means without getting involved in too much physics but failed to find a ...
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5answers
2k views

SMD IC mounted upside-down inside a drill hole for extreme low-profile requirements

I don't know if the title is descriptive enough, but I came across this PCB and could stop to wonder about its brilliant design. It is an aftermarket trigger controller for an airsoft gun that works ...
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1answer
58 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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2answers
217 views

Thermal Management for Arcol HS50/HS100 50/100W Wirewound resistors

I'm designing a 100W dummy load for a guitar amplifier using Arcol HS50 and HS100 resistors. Here's a link to the datasheet: http://www.arcolresistors.com/wp-content/uploads/2014/03/HS-Datasheet.pdf ...
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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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2answers
193 views

How Can I Find “temperature coefficient” of a Battery?

I am studying mathematical modeling of a battery in simulink and for this it is necessary to determine some parameters. I'm stuck in the part where I need to determine an alpha parameter, which would ...
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1answer
54 views

Thermo Electric Cooler(TEC) for ICs

I am designing a 9u rack server with optical ports. I want to implement Thermo Electric Cooler(TEC) for cooling the ICs(switches, FPGAs) on board, so that I can reduce the fan speeds. Is this a good ...
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1answer
164 views

MOSFET mechanism of failure: was it the heat?

I am debugging a failed MOSFET (IRF6662), and in the process of doing so, am having difficulty understanding fully the thermal behaviour of the FETs. Two FETs used for DC switching both failed short ...