Questions tagged [thermal]
Relating to temperature rise, the flow of heat, or cooling of components
615 questions
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Mounting and Connecting VS-FC420SA10 for H-Bridge Circuit
I’m designing an H-bridge circuit using the VS-FC420SA10 power MOSFET, but I’m unsure how to properly mount it on a PCB and make the correct connections.
Specifically:
Are there recommended PCB ...
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Which thermal resistance should I use to determine thermal dissipation of this IGBT? [closed]
I calculate losses for IGBT = 16 W.
Which thermal resistance should I multiply it by in order to know the temperature
Tjc = 0.34 C/W
Tja = 40 C/W
Why this big difference?
If I don't use a heat sink ...
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PCB layout, number of vias
How do you calculate the number of vias needed in a PCB?
My situation - I have a 4 layer board, I have power polygon on all 4 layers stitched using vias.
I used KiCad calculator for via sizing, I am ...
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Thermal equivalent circuit simulation
I have built-up an thermal equivalent circuit and want to simulate it with LTSpice.
It worked very good until I added some features.
I don't understand why the voltage makes a jump in the beginning of ...
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Best Dimming Cycle Period for longevity of a heating element
I want to 'dim' some 3kW heating elements to provide variable output i.e. between 0 & 100%.
I intend to use zero-crossing solid state relays.
let's say, for example, I want to run the heater at 50%...
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Thermal Protector Schematic Symbol
do you know what is the schematic symbol (from IEEE or whatever) for an electonic design of a thermal protector (Part Number: BW-ABS-60℃ - it is Normal Open Switch)?
Also, the BW-ABS-60℃ it is Normal ...
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Grounding the thermal pad of high power LED?
I am designing a PCB for a high-power RGBW LED, such as the Cree XLamp XM-L or pin-compatible Prolight PBLA-15LTE.
From Cree Datasheet
Can I ground the thermal pad? Cree datasheet says "...
- 18.6k
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Reducing LDO Power Dissipation with a Series Diode?
When trying to slightly limit the power dissipation of an LDO, is it a good approach to place a diode/Schottky in series with VIN to drop the input voltage slightly and shift some of the power ...
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Confused with thermal pads and SOT-223 tab
The SOT-223 has an exposed tab pin and this will be connected to the the OUT pin. In the table below, it shows the thermal resistances for different copper areas.
My question then is, to achieve the ...
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Thermal Relief – Yes or No?
In my PCB design, I have 0402 components connected to polygons. To reduce the risk of tombstoning, I connected them using thermal relief.
My guiding principle is that if heat dissipation is not ...
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How do I choose a fuse to ensure a MOSFET will be protected?
I have a MOSFET (JANSR2N7624U3) that I want to protect from a short circuit condition. Lets say the applied voltage will be 5 V over the duration of the short. From the SOA graph of the MOSFET, that ...
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AD623 Instrumentation Amplifier Produces Weird Output When Cooled Down
I am using an AD623ARMZ instrumentation amplifier supplied with 3V to amplify the signal from a Wheatstone-bridge - based pressure sensor. When testing the system in a thermal chamber with the ...
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What's the white substance spread across this thermal fuse and these two resistors?
The thermal fuse on this bed warmer controller tripped and I'm planning on replacing it. It's the one between the two fat resistors in the center of the board with longer axial leads.
Why does it have ...
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Dryer Thermal Fuse
Is it okay to replace a 250V-10A-150C dryer thermal fuse with a 250V-25A-150C thermal fuse? My dryer is a Maytag PYE2300AYW
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Slow rise time for a temperature sensor
I have a consumer-grade Bluetooth LE tempeture sensor like this:
I noticed that, when moving this device from outside (+3°C) to inside (+20°C), it takes a huge amount of time to get to the right ...
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Thermal considerations: how to read graph of copper area vs. current?
I'm struggling to understand the chart of device current versus area of copper for heat dissipation in the datasheet for an LT4423 ideal diode and load switch. My output current will be around 1A at ...
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Best location for a heat sink - On top of SMD package IC or bottom of PCB
I have a circuit board with several MOSFETs in TO252 and TO263 packages as well as other IC with exposed pads on the bottom.
I need to cool these parts and have 2 options:
Glue a heat sink directly ...
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Thumb rules for heat dissipation to ambient air (convection)
If I have a component (linear voltage regulator or a power mosfet for example) mounted on a flat plate of aluminium (it being used as a heat sink), how do I go about estimating steady state ...
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Thermal resistance from junction to case vs junction to ambient
I have been trying to measure junction temperature of some ICs in a PCB board and their IC packaging vary between TO-252, DDPAK and TSOT26 types. For the TO-252, DDPAK packages there is exposed copper ...
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Soldering a thermal fuse. 92°C
In my Alde 3010 caravan heater the thermofuse is gone. It is soldered on a printcard, and I wonder if there is any tips regarding soldering a new one on the printcard. The fuse will hold only 92°C so ...
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How to make an NMOS model SOAtherm compatible in LTSPICE
I am looking to do some thermal simulations for switching power MOSFETs. LTSPICE ships a small handful of NMOS parts that have thermal modelling parameters defined such that they can be used with the ...
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Why is thermal conductivity of thermal interface materials so low?
I need to reduce the heating of a battery that is inside a device with metal casing. I was thinking of using the metal casing as a heat sink. To do so, I need to use a thermal interface material (TIM) ...
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PCB layout guidelines Magnetic Sensor
I am using this IC from TI in my design.
The layout design guidelines and typical layout is given below.
I have some questions regarding the layout guidelines.
It says that
"Common passive ...
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Thermal printer head made out of PCB
I'm interested in only the thermal printer head, the part the gets hot. This question is not about the motor, gears, etc.
First, I would like to know as much as possible about a standard thermal ...
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Why does this MOSFET amplify more and more the longer it runs?
I built a simple power amplifier using a IRF510 MOSFET in a common source configuration: The incoming signal is connected to the gate, source goes directly to ground, and the drain has a 100 uH ...
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Case to Ambient Resistance, D2PAK soldered to PCB
I'm trying to calculate junction to ambient thermal resistance of a D2PAK soldered to a PCB with no aluminium heatsink, no thermal vias (PCB is 4-layer 1 Oz/layer).
At 10A power dissipation of the ...
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Can I use a brushed DC motor at higher-than-rated duty cycle at reduced load?
I have a linear actuator powered by a brushed DC motor which I got from an adjustable bed. The actuator label has the following information:
Input Voltage: 24V DC
Max Load: 6000N (Push)
Speed: 4.2mm/...
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Proof showing thermal noise of 2 resistors in series behave as a single noisy resistor
For the second part of this question, I came up with two slightly different answers? I believe it's the second one however I am not too sure which one would be the correct one.
First one:
Second one:
...
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Thermal fuse replacement
I need to replace a failed thermal fuse, but I cannot match a replacement exactly. I need a ShengPing SPF70-73C, TH=45C, TM=115C/10a @ 250v. How close do I have to match these specs, over and/or ...
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How does Cu plane thickness really matter for PCB heat flow?
This is a follow up question to an earlier one. If we trace the heat flow, the real bottle neck is the thermal impdeance between PCB surface and ambient air. As long as you dont work around that, ...
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How to best relate a case temperature measurement with the actual junction temperature?
If I have 4W of power dissipated through a transistor (as derived from measured current and the datasheet's on-resistance) and I measure 40 deg. C on the case of the transistor, what is the best way ...
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How to remove an old epoxy-like thermoconductive compound?
I'm not sure if this is the place to ask or it would be better suited for retrocomputing.
I'm salvaging some old components from old boards and I came across a very hard blue thermal compound that a ...
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What's the purpose of a large thermal pad without a heatsink?
I found this thermal pad on a controller board for SATA to USB enclosure. It's stuck on the SATA to USB bridge ICs. You can see 2 ICs to the left of it. There was an identical thermal pad adhered ...
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Protecting a soldering hot plate with thermal fuse
I am DIYing a reflow soldering hot plate, with an SSR allowing to regulate the hot plate temperature. However, I understand that SSRs can sometimes fail closed, which basically means that this would ...
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Can I treat the thermal shock test temperature as the continuous operating temperature of a conformal coating?
We are using this conformal coating on our design, HumiSeal 1B73EPA.
However, it does not state in the datasheet the continuous operating temperature for the coating, only the thermal shock test ...
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Is the difference in thermal resistance for putting a thermal plane on the outer layer vs an inner layer really only like 10%?
In MOSFET datasheets you often see something like junction to ambient thermal resistance of 40K/W being achieved using a 1" x 1" pad on the drain.
The main problem with this approach is ...
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SOA Mosfet Confusion
I am using mosfet (IRHJ9A7234) as a load switch and Id current is about 0.7A and maximum Rds from datasheet is 110mohm. So I thought based on power calculation P= I^2*R = 77mW which is way below than ...
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how to make heat sink under heat pads in kicad 7
Retired user here that have not designed a circuit in the last 3 years.
So I got myself KiCad 7 and boy oh boy things have changed!
Mostly for the better, but some things I used to do are now a real ...
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Thermal EMF on shunts
I tested the accuracy of a shunt resistor of 20 μΩ by applying short pulses of 100 A. At lower current levels near 0, I noticed the sensed current had a variation of ±300 mA. I did some research and ...
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IC thermal pad: Place heat sink directly over bottom-side thermal pad and thermal vias
If a VQFN package (below) has a thermal pad and thermal vias beneath it, the bottom layer should have an identical pad to act as a heat sink.
Is it typical to surface mount a heatsink on the bottom-...
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IC thermal pad: Duplicate zone in inner layers also?
Question
For a passively-cooled portable device (fanless, ambient cooling), what are typical methods to supplement the thermal pad of an IC to mitigate device temperature rise, (beyond efficient ...
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Current and voltage, thermal flashers (bimetallic blinkers)
I am looking for voltage vs time and current vs time plots at the load side for an automotive old time turn signal blinker in series with a switch and a standard 21 W incandescent light bulb. I was ...
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How can I measure the internal resistance of a thermoelectric generator?
How can I measure the internal resistance of a thermoelectric generator? Can I use a standard multimeter? I am using a TEC1-12706B thermoelectric generator. I tried to use a standard multimeter to ...
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Thermal conductivity of 1600W/m·K?
I am comparing different thermal conductivities in the market and found that the thermal conductivity goes up to 1600W/m·K for a thermal sheet, but a thermal paste is still 0.65 W/m·K.
Does it make a ...
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Mounting an 11W SCR with a Flat Profile
I have two SCRs in my design that will be switching up to 15A at 120-240VAC. The two devices will split the power, with each one conducting a half cycle. I'm considering using the S6025 by Littelfuse.
...
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PCB as heat sink - how to calculate the area
I got an Inverter of 6 MOSFETs and I need to estimate the PCB area for keeping the junction temperature below 100 °C.
The losses per FET are 0.21 W which leads to a max. Rthja = 143 K/W (junction to ...
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Estimating GaN HEMT junction temperature
I think it's quite a simple question, but the solution is not so obvious for me.
I know the equation Tj=Ptot×Rth+Ta, the thermal resistance Rthj-a and RDSon temperature dependance come from the ...
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8.3 kW DC brushed motor controller thermal management
I'm designing a brushed DC motor controller for an 8.3 kW, 24 V, 350 A forklift motor.
I will be controlling only one direction so I'm using a 70 kHz PWM from an MCU.
The circuit will be a push-pull ...
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How to derive thermal time constant from a MOSFET's datasheet?
I use the Vishay SiA440DJ MOSFET in a PMSM inverter. For thermal simulation in Maltab/Simscape I need to provide thermal data. On pg. 1 of the datasheet the thermal resistance Junction to ambient = 80 ...
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How much power in an IC to feel hot
Is there any rule of the thumb at which power dissipated in an IC one should be able to feel that it is hotter than the other components?
More specifically, I have a "signal" that should ...
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