Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [power-consumption]

Power consumption is the actual energy demand made on an existing power supply (e.g. battery). Consumption of electric energy is measured in joule (J), but for practicality often watt-hours (Wh) are used.

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How to Measure Power Consumption on Extremely Low Power Devices?

This might be old news in a half a decade or two but by today's means, I am referring to electronic prototypes and designs which would draw in a μA (uA) and even nA range of current. Some recent MCUs, such as SAMD21 that I am using atm are armed…
Mehrad
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Can we reduce power consumption of digital interfaces by using high impedance transmission lines?

Transmission lines must be terminated with the same impedance as the transmission line has itself to get an impedance matching and avoid reflections at a high impedance end point. This termination resistance closes the current loop between two…
jusaca
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Why does voltage not appear in the battery life calculation?

I have a PCB with a few radio modules on it. In its various states it currently uses anywhere between 100 µA and 100 mA. I can calculate how much time it spends in each of its states over a given year. The radio modules on my PCB all have a wide…
Eliot
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Relation between power consumed and MCPS (million cycles per second) consumed on a processor

I have been working on a ARM cortex A8 board on MP3 decoder. While doing this I have a requirement saying the MP3 decoder solution I am doing should consume 50 mW. This generated few questions in my mind when I thought about it: I recall that…
goldenmean
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For a mathematical operation in CPU, could power consumption depend on the operands?

Obviously, the number of operations affect a CPU's power consumption, but does it solely depend on the operations themselves? For example, adding 0 and 1 involves setting one single bit, but adding 0xFF and 1 requires clearing 8 bits and setting one…
polfosol
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Why can't electronic systems use constant current power source and vary the voltage as power consumption varies?

Today, electronic systems use constant voltage power source. Current consumption varies as power consumption varies. Why can't electronic systems be designed the other way round? Using constant current power source and varying the voltage as power…
user768421
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Do Step-Down Transformers Increase Total Power Consumption?

Firstly I am not at all experienced in electrical matters so forgive any wrong terminology. Here's the situation: I recently moved out of US to a country that uses 220v. We have a single phase step-down transformer that provides 120v to the entire…
mFabien
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What is the best way to estimate the power consumption of an Atmega328p microcontroller?

I'm currently working with a barebone Atemga328p microcontroller implemented within a battery powered design. I've realized I'm pretty clueless on how microcontrollers are rated on power consumption. Referring to the data sheet containing…
Izzo
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Single LED powered directly from AC mains

Today I disassembled a power strip (power extension) and found a LED connected directly to AC with a normal resistor (not a power resistor). How is it working as I thought it would be burned in no time? The resistor value is 220k.
mohammed ashker
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What is typical power consumption of FPGA devices

I am new to this site and had one question. I know typical CPUs have power consumption (TDP) in range of 100-200W, for example Intel Core2. I wanted to know what is typical power consumption of FPGAs. I saw this paper, where it says power…
user984260
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Relationship between I2C drawn energy / power consumption and data rate

Referring to just what the I2C lines draw, am I wrong thinking that the higher the clock frequency the shorter the time there will be (the same amount of) current flowing through the pullups and thus lower power consumed? side qeustion I don't…
kellogs
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Convert VAh to kWh

Sorry, this might be a stupid question as I'm not an electrical person. I'm analyzing an electricity consumption dataset and the consumption is measured by apparent energy (VAh). How do I convert this VAh to kWh as normally seen on a power bill? Or…
foo
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If I plug in a USB wall adapter but don't have a device hooked up, will it use power?

So let's say I have a phone and a USB Wall Adapter. If it is plugged up, but I don't have my phone hooked up, will it use power? And if so, will it be a noticeable amount when left plugged in for extensive periods?
Elijah Goforth
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Performance analysis of embedded firmware

I'm working on a project where I want to make the software the most power efficient it can be on the system. What ways can I do performance analysis of my system? I'd like to run the system off AAA batteries but would like to estimate how long…
Dean
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Can I put a resistor in parallel with LED to limit current consumption?

I want to power one 3V LED with a 3V source. Let's say I'm using a 10 Ohm limiting resistor, and the LED eats 20mA of current. Using a CR1225 with 50mAh capacity that will last for about 2.5h. What if I connected another 10 Ohm in parallel with the…
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