Questions tagged [power-dissipation]

Anything related to power dissipation in electrical and electronic circuits and components, i.e. the process in which electrical energy is converted to heat when current flows through them.

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28 views

TTL Gates Power Dissipation Values

I am not finding any datasheets that provide clear information about the power dissipation of some gates of the 74LS series: 08, 02, 04, 00, 32 and 86. Can someone help?
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59 views

Reduce DC power supply for battery charging

I have a DC power supply from either a WIFI router or printer (not sure) rated for 13.5V @ 1.2A output. This is a replacement charger for an electric ride on car as it was originally 6V and I've ...
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64 views

Comparing power consumption of different FPGAs

I want to compare power dissipation of FPGAs from different vendors, the I/O count and the logic resource shall be matched as close as possible when choosing the FPGAs. I want to create a trivial ...
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2k views

How much power does LM7805 dissipate?

I'm using an LM7805 in voltage regulator mode. Vin is 15V Vout is 5V (regulated) The attached load draws 200mA How to calculate how much power the LM7805 would dissipate in this setup (and whether ...
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55 views

Lower duty cycle less efficient?

Assume you have a DC voltage V, ideal switch (no switching losses) operating at some frequency f and duty cycle ...
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239 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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80 views

Over voltage protection IC keeps burning

I am currently working on a project where over voltage protection is necessary. I made a test circuit using an LP5300 (SOT23-6 type.) https://datasheet.lcsc.com/szlcsc/1912111437_LOWPOWER-...
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35 views

Mosfet Thermal Resistance calculation

I went through the application notes of infineon and TI. In the datasheet on the MOSFET, there is a junction to case Thermal Resistance given. Can we use these values to calculate the power ...
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32 views

P-MOSFET power dissipation spike when turning off (10 - 100khz)

I designing battery charging circuit, I found the following step down converter for charging. The target is to charge a battery with 3-4 A, but the P-FET (NTF2955) becomes very hot at 0.5 amps: I ...
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31 views

Finding the power dissipation in a wye-connection given resistors

The problem that I'm attempting to solve is the following: Three 1000 Ω resistors are connected in Y to a 200-Vac line. The power dissipation of the Y combination would be _____W. a. 42 b. 41 c. 40 d....
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50 views

Why do I get such high values when calculating the power dissipation of MOSFET in boost-converter circuit?

I'm a hobbist interested in electronics so I don't have any "professional" training on that. Currently I'm trying to design a boost converter and now I'm stuck at some calculations. I wonder ...
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130 views

Calculate voltage drop across Linear MOSFET in saturation region

Considering the below schematic, how is the voltage drop across the MOSFET calculated when it is operated in the saturation region? I am trying to calculate the power dissipated by the MOSFET so that ...
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34 views

Can I exceed the 120mA per channel on the TLC5940 if I use external resistors in series with LEDs?

Datasheet The TLC5940 drives 16 channels of LEDs at constant current using PWM. I assume the 120mA limitation per channel as described in the datasheet has to do with how much power the HTSSOP ...
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31 views

Am I calculating my shunt FET power dissipation correctly?

simulate this circuit – Schematic created using CircuitLab I'm designing an LED driver circuit that requires very fast PWM switching at a high resolution (10bit at 30khz requiring a minimum ...
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65 views

High thermal load PCB for short duration

I got 30 buck converters on 4 layer pcb (70x130mm). Each will dissipate ~2W for typically 30 seconds followed by a very long break >10min, and I'm worried about overheating. Although it is not a ...
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3k views

How closely should I space my thermal vias?

How closely do you pack your thermal vias? I know that more vias divides the amount of heat each via can move and that smaller vias allows more vias to be packed together. Knowing this, it seems ...
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4answers
421 views

Heat Dissipation Calculation for MOSFET

My challenge at the moment is dissipating 60A of load current through an array of MOSFETs. Here are my specs: No cooling fans Heatsinks allowed, if needed FET and/or heatsink cannot attach to the ...
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23 views

overloading rated current capability of a connector

If each connetion of a screw terminal (the one in question in the picture) is rated for 3A at 380V, is it probably safe to use each one for 12A at 12V? Is there a way to work this out? Thanks
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LM337 regulator not warm

I built this circuit and am getting correct voltages except the negative regulator (lm337) is cool to the touch whereas the positive regulator (lm317) is very warm. Why?
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34 views

Reconciling power dissipation and output characteristic of BJT

From the datasheet of 2SC1384 I got the following characteristics. I plan to use this transistor in an RF amplifier. The power dissipation characteristic sets a limit on the dissipated power of the ...
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71 views

How to provide a 5 volt rail from 24 volt source

Edit: Added practical observations at bottom. I need to provide power to an ESP8266 12E NodeMCU board, and my "raw" power is a 24 volt "wall-wart" PSU. My first thought was just to use a 7805 with a ...
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49 views

Power dissipation of TLC6C5712-Q1 LED Driver IC

I am using this TI LED Driver IC to drive 9 LEDs I want to calculate the Power Dissipation of the Resistor (20k 1% 0402) which I have connected to the IREF pin. To calculate the power dissipation of ...
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114 views

Verifying maximum switching frequency calculation of a hard switching IGBT

I have recently been working on a power H-Bridge meant to drive an inductive load in hard switching mode. I calculated the maximum operating frequency limitation due to maximum power dissipation of ...
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100 views

Power dissipated in resistor

I have the following problem: Consider the graph below What is the power dissipation in a 75 \$\Omega\$, when the voltage across it is the plotted voltage above? Okay, so my idea was to split the ...
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53 views

Given the surface area, volume, and temperature of an IC, can you calculate how much power is dissipated?

Assume the temperature of the IC is uniform and constant and the surface area and volume are known. Can you calculate from these values the power dissipated by the IC through heat? If not, what ...
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Power dissipation BJT transistor as voltage follower

Following the discussion from this thread I am finalizing my calculations. I am not sure that I am calculating the power dissipation correctly. Given the following circuit I need to operate the opamp ...
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9k views

How are LEDs considered efficient?

I've always found circuits containing LEDs hard to understand, please bear with me. I know most people find it easy, but I'm confused by them so some of my assumptions might not be correct, please ...
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208 views

Diode selection for step-down Converter

I have built quite some buck converters for ~3A@3-5V (~1MHz, 24V Input) and I always used schottky diodes due to their low forward voltage drop (and therefore low power dissipation during free ...
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45 views

SPICE IC model in-circuit power dissipation

I'm looking into a way to calculate the power dissipation of any arbitrary IC in circuit on SPICE. I eventually hope to create simple scripts that can list power dissipation of the device and ...
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77 views

Possibility of dissipating 20 W via Nichrome wire safely

I am looking to use 1 foot (0.3 meters) of 32 AWG nichrome wire to dissipate roughly 20 watts of power. Assuming the wire was submersed in still transformer oil, would I be able to do this without ...
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44 views

Advice on a voltage measuring circuit

I've been working on a voltage divider circuit that will hopefully allow me to measure voltages between 0-60 kV DC (80 W) as 0-889 volts DC. The voltage divider section that is used to measure the ...
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2k views

LM317 - Calculate dissipation due to voltage drop

If I use a linear voltage regulator as LM317: Input voltage = 24 V Output voltage = 5 V (so a voltage drop of 19 V) Mean load = 480 mA (peak load = 700 mA) From the datasheet, I read that maximum ...
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5k views

LED strips: 46% resistive losses?

I recently bought these LED strips. They are supposed to run on 12V/72W and have 300 x the SMD 5050 LEDs on it. Schematic: simulate this circuit – Schematic created using CircuitLab The ...
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545 views

Precaution and Rules to Paralleling Power MOSFETs

I'm going to use a Full Bridge Inverter for my application. The problem is that the current which flows through the MOSFETs when they are ON can reach 70A RMS and the power dissipation is too high. ...
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154 views

Calculation of Power Dissipation of Memory ICs and Microcontrollers

Can someone tell me how to calculate the power dissipation of digital ICs like Nand Flash, QSPI NOR Flash and Microcontrollers? For Microcontrollers, we can get the power dissipation for GPIO like, ...
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241 views

Should thermal pads be connected to GND or not?

I'm creating a footprint for the TPS2141 (LDO and current limiter) and I wonder if the thermal pad should be connected to the GND plane or if thats a bad idea? Should it just have its own copper zone ...
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82 views

Calculating Power Dissipation in a Filter

Apologies in advance if my question seems too basic. I don't really know where to go from here. I understand that power can be calculated as P = IV or P = V^2/R or P = I^2 x R. I think I'm not ...
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279 views

Quiescent current vs GND pin current for Linear Regulator IC power dissipation

I want to confirm that, for a linear regulator IC, quiescent current multiplied by the input voltage accounts for the IC power dissipation(including drop-out voltage loss). I ask because the ...
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2k views

Heatsink on underside of PCB

I have prototyped some DC-DC converter modules, and they work well. However due to size, I don't have a huge amount of copper pour for them to dissipate their heat. I have used 2oz copper but the ...
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1k views

Transistor power dissipation rating

I'm trying to build the following circuit Except mine is a 24V ~20A (500W) motor, so I need to swap the components. I'm currently looking into transistors and I've stopped on the 2N6284 (NPN) ...
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170 views

Triac power dissipation

I'm driving a high power load with the BTA440Z (datasheet): line voltage is Vac = 230 AC, load power is P = 1.33 kW, thus load current is ~ I = 5.8 A. If i swap the load with another ...
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124 views

Thermal resistance Junction - Maximum Power dissipation

I want to understand the real meaning of the parameter 'Thermal Resistance Junction to Air (°C/W) to calculate the power dissipation. So for example if the value of this parameter is 250°C/W, should I ...
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105 views

POWER MOSFET - Thermal Design

i have some doubts about with this thermal design? first, the calculations and infos: My load (a motor) uses an average current of 7A, I could not measure the current peak at the beginning of the ...
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2k views

Average power dissipation in radar

Hello there here i want to calculate average power dissipation of radar My question is here i tried to solve it this way Average power = peak power*Duty cycle here transmitted power is 300kW and ...
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120 views

ESD Diode - clamping voltage

I'm trying to replace an existing ESD diode(PESD1CAN) in my application CAN circuitry due to some reasons, I've found an alternative ESD diode(RSB27C2), but compared to the diode that I already have ...
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59 views

How do I treat this “lamp” to find power dissipated?

This is my circuit. I need to find the power dissipated by Vlamp. So the lamp turns on if the Vlamp is more than 2V. When the ...
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47 views

Determining Absolute Maximums for IC Output Current and Power

I'm having a small gap in understanding with a project I'm working on. The project is reliability related and requires looking at the absolute maximum values for some 54ALS family logic (Max Vcc, ...
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2k views

peltiers in series

Im trying to understand the way a peltier modules behave as they are new and intriuing to me, I have ordered a few tec1-12705 units from china and done a little research trying to understand it. Some ...
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5k views

Power Dissipation of Power Mosfet

I am doing power dissipation of a power mosfet. My design requirements are :- 20A @ 12-20V (Ambient temp will be around 50 deg Celsius) The mosfet I am using is :- http://aosmd.com/res/data_sheets/...
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92 views

Conceptual paradox with resistance in loop/node analysis

There are loop/mesh analysis and node analysis corresponding to Kirchhoff’s voltage law (KVL) and Kirchhoff’s current law (KCL), respectively. Let's consider three elements, R,L,C, connected ...