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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8answers
219 views

Using 110 Vac incandescent light bulb at 220 Vac with a series diode

I have a 110 Vac incandescent light bulb but I need to use it in 220 Vac. If I add a diode in series with the bulb, the RMS power is the same as before but the peak value of voltage and current is ...
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1answer
175 views

About power dissipation of capacitors and inductors & I-V phase difference

For instance, The Art of Electronics (by Horowitz & Hill) states that ideal capacitors cannot dissipate power, even though current can flow through them, because the voltage and current are 90° ...
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1answer
70 views

Does voltage drop resistor affect power dissipation?

I need to power an RFID from 24 V DC voltage. The RFID requires max. 9 V and max. 120 mA. The RFID suggests a 7809 linear voltage regulator. I thought too much and I want to use a 7809 because if I ...
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0answers
41 views

Mosfet power dissipation in this example

I am trying to design a buck regulator with the following specification: Vin = 24V Vout = 5V I max = 8A Fsw=300k. The load is basically a long strip of RGB LED's. Which in certain cases would be all ...
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1answer
77 views

Is there a "rule of thumb" for power dissipation of an enclosed circuit to help determine when to do a thorough analysis?

I'm starting a project and the electronics will be enclosed in a wood sign outside. Even though it's shaded, I'm concerned about heat buildup in the summer. Is there some rule of thumb that says if ...
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2answers
109 views

LM317 is dissipating too much power

I used an LM317 in my circuit to get a regulated 1.5 volts output from a 3.7 volt battery using two resistors (220 and 60 ohm.) It worked fine, but the circuit dissipated too much power even when not ...
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2answers
131 views

How to calculate the pulsating current flowing through a shunt resistor?

If the current flowing through the shunt (0.5 ohm) is in pulsating form (PWM with 50% duty cycle and 100 Hz frequency,) how do I calculate power loss through shunt in order to choose proper for ...
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2answers
222 views

Buck / step down voltage in limited space

I am designing a small PCB. The supply voltage is 12V, but I also need 5V with supply of maximum 250mA. The most obvious solution is to use voltage regulator - there are plenty of them and some like ...
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2answers
119 views

Calculation of heat generated by a battery pack

I have to calculate the heat generated by a 40 cell battery. The max. voltage is 4.2 V, nominal voltage is 3.7 V and the cell capacity is 1.5 Ah, discharging at a rate of 2 C. If I calculate the heat ...
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2answers
1k views

Can PCB dissipate heat from MOSFET so that a heatsink is not needed

I am using a DMP3007 as a reverse polarity and over voltage MOSFET. The maximum planned load is 10 A and voltage may vary as the load is a constant current load. simulate this circuit – ...
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6answers
114 views

With a constant-current, constant-voltage power supply, does the total length of the wire affect the heat produced per metre?

This seems like it should be obvious, but I can't seem to get my head around it. If I have a length of wire 7 metres long and it has a total resistance across its whole length of 2 ohms, and I connect ...
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2answers
44 views

use of power dissipation in transistor and using higher current rated transistor

I am using using a PNP transistor in one of my application to switch on and off the boost convertor. My requirement for collector current is 500mA. My question is does it matter if I use 500mA/600mA/...
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0answers
52 views

SiC MOSFETS power dissipation; for heat sink sizing

I want to calculate the max. power dissipated for SiC Mosfet in a 6.6KW CLLLC resonant converter with full bridges on primary and secondary sides. Let's consider the case when the input voltage is ...
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1answer
72 views

Is power dissipation for SMD resistor rated only for air dissipation or air + PCB?

I know that PCB with good copper area will dissipate much more heat than air surrounding the resistor. However, the datasheet for Yageo resistors is vague about whether the dissipation ratings take ...
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2answers
212 views

Very hot live pin on kettle plug

I moved my kettle just after boiling it yesterday and noticed the live pin was very hot. None of the other pins are hot. It's a bs 1363 type plug and socket. And a <2 year old kettle. After a full ...
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2answers
104 views

How to create a design that uses specific % of DFF and LUT count in FPGA to measure power dissipation?

I want to create a design which does not perform any specific useful function but utilizes specified amount of logic resource in the FPGA e.g 50% DFF and LUT or 50% DFF and 25% LUT e.t.c. I shall then ...
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2answers
111 views

Heat sink sizing for LDMOS

There are many heatsink calculation Q&A's on SE that I've looked through. One very reasonable answer tells me that I can calculate heatsink C/W as follows: $$\frac{T_j - T_a}{P_d} - R_{JC} = R_{...
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0answers
40 views

Power Dissipation - Sizing up Power Supply Needed

I wanted to understand what size power supply is needed for the following: I am getting confused with the Icc value and Ioh,Iol etc values in the datasheet. My question is, how much current will I ...
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1answer
136 views

CAN physical layer fault conditions Short circuit to battery on CANH and CANL lines analysis

In case of short circuit to battery on CANH, would the current flow as analysed below ? This is in the case of CAN transceiver TJA1042T and I got the internal block of the transciever by NXP. Data ...
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2answers
678 views

How to be sure that a ceramic capacitor can manage a RMS current?

I'm in the middle of a design and I need a capacitor of: 10µF Rated at 10V Has to handle a ripple current of 250mA RMS, at 400kHz Most electrolytic capacitor data sheets give a maximum RMS value for ...
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1answer
30 views

How can I determine PD for given impulse, based on transient thermal impedance for BJT?

I have (selected) a BJT to work with rectified mains application. Transistor is PBHV9560Z (600 V, 0.5 A PNP) https://assets.nexperia.com/documents/data-sheet/PBHV9560Z.pdf Under normal operation ...
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1answer
78 views

Power dissipation calculation for FPGA-ADC interface

An FPGA can be interfaced with an ADC using CMOS or LVDS. Is there a way to use simulation to predict the power dissipation of the I/O blocks for a given operating frequency for this interface? If so, ...
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0answers
41 views

Maximal power dissipation of the resistances in this circuit

Assuming I have this circuit below with : Ic = 200mA , β = 100 , UCE = 15 V So with some calculations : Ib = 2mA , R1 = 4k7 Ohm , R2 = 75 Ohm If I want to calculate the power dissipation of both URV1 ...
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0answers
50 views

How can FPGA differential signal use lower power when it has two lines instead of one?

I am a bit confused about differential signaling on FPGAs. I am trying to figure out how does power dissipation in FPGA differential signaling compare with power dissipation in FPGA single ended ...
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1answer
245 views

Can I choose a heatsink based on its thermal design power (TDP) for cooling LED chips?

I am confused about TDP ratings and what they refer to actually. The reason I am confused is because most modern CPUs and GPUs, although not ideal, are able to sustain very high temperatures (80 C or ...
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2answers
50 views

Power input connector for power distribution board

I have been looking at several different power distribution module designs and the all seems to use a large bolt for the main power input. I am curious what these connectors are called and how they ...
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1answer
83 views

Power dissipated between two points

In the follwing, if the power dissipated between a and b is 210 watts, what is the value of Vb?
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1answer
74 views

How does complex loading affect an op amp's power dissipation

I'm trying to calculate power dissipation in a complex load. I know that the power loss due to the resistive component is dissipated, and that the power loss due to the reactive component is canceled ...
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1answer
97 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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1answer
95 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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1answer
75 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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2answers
114 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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1answer
89 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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2answers
310 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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2answers
150 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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2answers
105 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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2answers
400 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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2answers
50 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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1answer
71 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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2answers
86 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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2answers
40 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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1answer
66 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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1answer
81 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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1answer
145 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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1answer
128 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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2answers
91 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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0answers
62 views

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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2answers
1k 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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1answer
68 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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4answers
2k 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 ...