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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4 votes
2 answers
782 views

Voltage regulator not heating up ... How?

I connected a L7805 to a water fountain that I measured to be consuming 0.1 A at 5 V to regulate power coming in from three 5 W, 12 V solar panels connected in parallel. The regulator is not heating ...
1 vote
0 answers
29 views

Junction temperature vs transient current

I'm using the OPA551PA amplifier to charge a capacitor to various voltages. After thermal calculations, the worst case scenario is depicted here. TA = 40C, Vin = 36V, Vout = 18V, Iload = 50mA. Under ...
0 votes
1 answer
32 views

Chart/ table to visualize how hot a device is actually getting

Maybe my question will be a little funny. But it will be very helpful if you can give a little information about one thing. In electronics, we calculate power at various points/calculations to predict/...
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2 votes
1 answer
96 views

Which consumes less current in microcontrollers: Always HIGH pins or always LOW pins?

I am driving a P-MOSFET (IRLML6402) with ATtiny24A microcontroller. This is a battery powered system; that's why ATtiny is always on sleep. I originally configured a BJT which is driven by the ...
2 votes
1 answer
42 views

Maximum allowable AC voltage for film capacitors as a function of frequency

For a project that I'm working on, I would like to generate an oscillating magnetic field. In order to achieve this, I would like to create a series LC circuit with multiple film capacitors in series ...
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1 vote
1 answer
69 views

SOA and varying VDS

In a hot-swap application the FET spends some time in the linear region/Saturation region before it moves into the ohmic region. Here is a snippet of the turn on waveform seen for a FET: Yellow is ...
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2 votes
5 answers
174 views

I calculated the power loss of a switching regulator and it doesn't match the datasheet. Am I missing something?

I'm trying to figure out how On Semi's LM2575D2T-5G is only 77% efficient. It's the fixed 5 V output version of the component. The datasheet gives Vin = 12 V and Iload = 1 A. Based on this, power in = ...
5 votes
2 answers
873 views

Is there a general rule to calculate heat dissipation of electronic equipment?

Is there a general rule for calculating heat dissipation in electronic equipment if it's not listed in the specs? I have a couple of projects coming I'm working on that require this. For one situation ...
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1 vote
1 answer
70 views

How to calculate power dissipation for an MT3608L current-mode step-up converter?

I'm using an MT3608L with an input voltage of 12 V to create a voltage of 18 V using the below schematic. As this is a cutout of a larger schematic, the input voltage is applied to the top left wire, ...
1 vote
1 answer
66 views

K155ID1 power dissipation

I build my own nixie clock with four digits (IN-14, 10k anode-resistor) with a seperate K155ID1-IC for each digit (so no multiplexing). Also, I am only using the 0-9 range, so every tube has one digit ...
1 vote
3 answers
82 views

Efficient Voltage Divider Battery Monitoring for 42V system

I'm designing a system that is powered from a 10S2P LiPo battery pack and I was looking for an efficient way to monitor the battery level. My microcontroller is 5V logic level, and I understand I can ...
1 vote
0 answers
99 views

Is it bad practice to connect a heatsink to my PCB's ground plane?

So, basically, I have this LED project which is going to dissipate lots of heat (I am assuming close to 50W) inside a case. The LEDs themselves are on a separate aluminum board which will be attached ...
0 votes
3 answers
52 views

Current limiter for VOD3120AB

I want to supply VOD3120AB with a voltage of 24v/2A from Power Supply. What is the value of the Resistor that I must add to the VCC of the VOD3120AB so that the VOD3120AB works properly? Information ...
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1 vote
3 answers
214 views

Power loss and voltage drop for a parallel wiring system

I'm looking to power a 50W load approximately 140m away using 48V DC. At the far end I will use a DC-DC converter to convert this to 12VDC where it will power a small DC powered network switch I have. ...
2 votes
3 answers
214 views

Calculate power dissipation of split-supply op amp for sinusoidal input

I want to calculate the total supply current and power dissipation of an op amp in a non-inverting voltage follower configuration with a split supply: simulate this circuit – Schematic created ...
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1 vote
0 answers
39 views

Buck regulator thermals calculations

Schematic: Specification: Vin = 24V Vout =5V Iout max = 8A Freq = 0.691 Mhz Assumptions: Good layout and FETs mounted on 1-2 inch^2 of copper. Calculations based on this doc: https://www.ti.com/lit/...
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1 vote
0 answers
184 views

Calculation of power dissipation of a MOSFET circuit

As a part of an assignment to design a common source amplifier, I came up with this circuit: simulate this circuit – Schematic created using CircuitLab The transistor is a 180nm technology with ...
0 votes
8 answers
309 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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2 votes
1 answer
227 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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0 votes
1 answer
82 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 ...
1 vote
0 answers
61 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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0 votes
1 answer
127 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 ...
0 votes
2 answers
177 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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0 votes
2 answers
184 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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-1 votes
2 answers
236 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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0 votes
2 answers
521 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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3 votes
2 answers
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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0 votes
6 answers
149 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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0 votes
2 answers
86 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/...
0 votes
0 answers
100 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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2 votes
1 answer
207 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 ...
0 votes
2 answers
649 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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0 votes
2 answers
142 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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0 votes
0 answers
82 views

How to create a copper pad for heat dissipation in Eagle?

The data sheet for this component, the RPX-1.0, says SW Switch node. Connect 6, 7, and 8 to large copper pad for optimal heat dissipation. Is a "large copper pad" an extra component that ...
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0 votes
2 answers
162 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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0 votes
0 answers
41 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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0 votes
1 answer
343 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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6 votes
2 answers
2k 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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0 votes
1 answer
36 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 ...
  • 501
2 votes
1 answer
122 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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0 votes
0 answers
42 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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0 votes
0 answers
64 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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0 votes
1 answer
380 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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0 votes
2 answers
62 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 ...
1 vote
1 answer
123 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?
2 votes
1 answer
95 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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0 votes
1 answer
167 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?
0 votes
1 answer
167 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 ...
0 votes
1 answer
97 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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0 votes
2 answers
220 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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