Questions tagged [low-power]

Low-power refers to electronics that are designed to use less power than their common counterparts. This is often a requirement because of limited available power, as in battery operated devices, or in cases with limited cooling capabilities, as in notebooks.

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52
votes
7answers
87k views

How can I get my atmega328 to run for a year on batteries?

Scenario I have created a nice electronic door lock for my dorm room. It is currently an Arduino Diecimila with a servo [un]locking the door. It has a numerical keypad with 3x4 buttons and 5 LED's (2 ...
34
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5answers
15k views

Why does a faster clock require more power?

If you overclock a microcontroller, it gets hot. If you overclock a microcontroller, it needs more voltage. In some abstract way it makes sense: it is doing more computation, so it needs more energy ...
29
votes
7answers
7k views

Smart ways to detect a button (less power consuming)

During a meeting for a particular project I was asked to think about the way to detect a push on a button with a MCU. The detection should consume as little power as possible. At the first glance, I ...
26
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5answers
5k views

Making a battery last a long time in a microcontroller circuit

I'm hoping to power an ATtiny85V for a nice long time on some small battery, probably a coin cell. I've looked into the software side, and my code is watchdog timer driven, has unused analog and ...
24
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5answers
9k views

How could have Banksy kept an RF receiver running for 12 years? [closed]

I'm talking about Banksy's "Girl with balloon" painting that shredded itself at auction. I think the general consensus is that he didn't, and that it was set up before the auction (or a couple years ...
21
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2answers
29k views

Some advice on charging circuit used in simple UPS

I have looked around for some way of having a 5 volt power supply that acts like a UPS. Basically want to use a micro usb connector for +5 have a battery and li-ion or other charging circuit that ...
19
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4answers
6k views

Why are vias bad?

I am designing a PCB with EAGLE and saw that it was trying to limit the amount of vias through the PCB. Why do you want less vias? Why are they bad? Do they bring extra manufacturing cost or is it OK ...
18
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3answers
22k views

Efficient low power regulation? i.e. 9 -> 5 Volts

For the sake providing as much current as possible to a small circuit, regulated down from ~9V to 5V (or 5V->1.5V), I have looked at some possible options. What I was originally going to do (maybe a ...
18
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4answers
11k views

Low power micro-SD card storage

We are building a low-power data logger based upon the ATmega328P, in order to make use of the Arduino boot loader and IDE, etc. Ideally power consumption should be less than 0.3mA @ 3.3V to get ...
14
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7answers
6k views

LEDs on a (battery) budget! – How can I lower the current through a LED without using up the battery?

EDIT: Here is a much brief version, the meandering motivated version is probably subsumed in the parent question on general battery life optimizations. How can I lower the current into a LED ...
13
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9answers
4k views

In which scenarios is it important to measure microampere?

With the situation of finding a new multimeter, I found myself lost to the number of available devices on the market. For sure, to find the most suitable device I have to set some requirements. While ...
13
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11answers
2k views

Low power radio + microcontroller recommendation? [closed]

I'm searching for a low power system-on-chip that combines: A processor (any achitecture) A radio (any frequency/bitrate/tx power) 2 or more I/O pins (ADC would be a bonus) Can anyone recommend a ...
13
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4answers
5k views

Waking Up From Deep Sleep Modes

Most microcontrollers (e.g. AVRs,MSP430s, PICs, etc) support a number of different sleep modes. The "deepest" sleep mode is the one that purports the lowest power draw (e.g. "Power Down", "Shut Down"),...
12
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3answers
2k views

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....
12
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4answers
36k views

Can I use multiple 18650 batteries in parallel with a standard MicroUSB 3.7V charger board?

There is this Bluetooth Audio Reciever/Amplifier board that I'm looking to get from ebay, and according to the diagram, there's a MicroUSB 3.7V lithium battery charger component in it. With my ...
12
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3answers
5k views

Low power, seven segment display

I want to display a 4 digit number on a small device that fits in a hand. I have a CR2032 3V battery at around 230mA, my microprocessor is a 8051 (in a BLE112) usually uses about 0.9µA and I want the ...
11
votes
12answers
33k views

Avoiding DC voltage drop over long distances

I am trying to power my IP camera over a long distance from the power socket (about 10m). The included power adapter, rated for 5V 2A is about 1.5m long. I cut the cable and extended it using a ...
11
votes
1answer
2k views

Is there such a thing as an ultra low power solenoid?

I am looking for a tiny push-type solenoid that can be driven with milliwatts. The plunger need only move 2-3 mm. Does such a thing exist?
11
votes
1answer
4k views

Is the Cortex M0 really low-power?

I'm using the NXP LPC1100 series CPU, which is their most low-power Cortex M0 offering. However, in the datasheet it states that under the most optimal conditions (sleep-mode + all peripherals ...
11
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3answers
1k views

Microcontroller Sleep Race Condition

Given a microcontroller that is running the following code: ...
10
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5answers
6k views

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,...
10
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3answers
794 views

Powering an IC from a GPIO line

I've got a low power application which will be powered from a Li coin cell. I've achieved satisfactory sleeping current with my chosen MCU. The application ADC IC however is a different matter: ...
10
votes
1answer
1k views

Why does this microswitch datasheet specify a minimum load current? [duplicate]

The Omron VX series datasheet mentions on page 6 that "Using a model for ordinary loads to open or close the contact of a micro load circuit may result in faulty contact.", and shows that their micro ...
10
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2answers
6k views

How to choose a low power Microcontroller?

Cortex-M0+ from NXP and Freescale claim they have world leading energy efficiency. TI Wolverine also claim they cuts power consumption in half and have the lowest power in memory, peripheral, standby ...
10
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4answers
728 views

Proper ways to disconnect ICs during low power states to avoid parasitic/backfeed supply

I’m working on a low-power battery-based AVR-based project that integrates a few different devices including a neopixel strip and an Adafruit pixie. When the overall device is quiescent, I’d like it ...
10
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4answers
2k views

Protecting Microcontroller Input Pins from Soft Power Switch

I'm working on a soft power switch for a microcontroller where a momentary switch can turn the circuit on (including microcontroller), and then when the switch is pushed a second time, the ...
10
votes
1answer
26k views

How does a smart phone measure the battery power?

A smartphone (assume Android) usually displays the battery percentage from 0 to 100%. I am assuming this is the usable power capacity of the battery. I have several questions: 1) How exactly does it ...
10
votes
2answers
790 views

Do batteries last longer with constant current draw or spiky current draw?

Do batteries last longer with constant current draw or spiky current draw? Or, as is implied by the accepted answer to "Making a battery last a long time in a microcontroller circuit", do some ...
9
votes
5answers
10k views

Measuring temperature with ±0.01°C accuracy

What is the most accurate way to measure temperature to ±0.01 °C? I have looked into using a Wheatstone bridge (with a minipot for minor calibrations) and an RTD for its precision and range. I ...
9
votes
3answers
4k views

Suggest a timer chip

I need to take voltage measurements separated by long delays (couple of hours) and beep a buzzer when voltage level is met. Power consumption is important. What I want is a simple timer chip like ...
9
votes
2answers
3k views

Autonomously-powered (battery-less) wireless pushbutton

What would be a feasible approach/circuit-design to make a self-powered wireless pushbutton, assuming it is even realistic? This is what I mean by each of the three terms: Self-powered: Power ...
9
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2answers
2k views

Minimum ATMega328 speed with UART

I am looking at designing a low-power project that will have an ATMega328 running at a low speed for lower power consumption. The current plan is to have the UART hooked up to a RF Link Receiver for ...
9
votes
3answers
5k views

ATtiny85 power consumption double expected

I'm trying to get an ATTiny85 to run off a battery. I have it clocked from a 16.384 MHz crystal, with the divide-by-8 fuse set. Vcc is 3.3 volts. Figure 22-7 in the datasheet says that at idle ( ...
9
votes
6answers
13k views

Best choice for low-power, short-range wireless communication

I'm working on a project which relies on wireless communication, and I'm looking for the best alternative. These are the design requirements: Is easy to interface with Arduino Works over a small ...
9
votes
1answer
287 views

LED current while off

I have a vague recollection that while off, a LED can actually receive light and generate a small current (in uA). Is that correct? How does that work? What is the best way to prevent this?
8
votes
3answers
764 views

STM32 - How does analog configuration of MCU pins affect the power usage?

When I was creating a new project using the STM32CubeMX, I saw a check box stating that setting all free pins as anlog will decrease the power consumption. I couldn't figure out how it works. How can ...
8
votes
3answers
12k views

Can I use two Arduino digital pins in parallel to keep a higher voltage?

I'm using a digital pin as a supply to a sensor (should draw ~7mA). Unfortunately, the sensor pulls the voltage of the digital pin down from 3.3v to 3.0v, which isn't enough for the sensor. Can I ...
8
votes
4answers
6k views

Low power design - switch out voltage divider using transistor?

I have a very simple voltage divider circuit for measuring the resistance of a platinum 100 Ohm resistor. I want to be able to switch out the voltage divider circuit from the power supply in order to ...
8
votes
1answer
13k views

Replacing incandescent bulbs with LEDs, unexpected behavior

I have an over-the-stove microwave/hood vent combo with 2 adjustable-brightness lights. The lights appear to be 12V lamps with a G4-style connector, and they burn out too often. I decided to go with ...
8
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4answers
6k views

Do Linear regulators have a minimum current to maintain their output voltage?

When I was searching Digikey for a ~6V to 3.3V Linear regulators, there was a minimum current column in the listing results. This kind of threw me because I didn't know that there was such a thing, or ...
8
votes
4answers
8k views

How to cut power off when a certain voltage from a sensor is reached?

I've built a simple Ni-Cd charger (basically a 0.1C current source) for some 1300mAh cells, that I want to stop when a certain voltage is reached on the cell. I tried to design the switch with an Op ...
7
votes
5answers
13k views

simple, energy efficient circuit to make single IR LED blink

I'm using a 850nm IR LED (spec sheet), and in order to extend my battery life, I'd like to make the LED blink (UF 1.9 V, IF 100 mA). I found a couple of links 1, 2, 3 but they either a) require two ...
7
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4answers
1k views

Minimum energy required for LED blink to be visible

I have a 5V schematic with 15n capacitor and I wondering if I will be able to blink an LED, powered from this capacitor. My calculations is that the capacitor will have about 0.2 uJ of energy. This I ...
7
votes
4answers
1k views

What's causing this power spike in STM32 low power mode

I'm using an STM32L073RZ on a bare board with just the CPU and decoupling caps. I'm powering the board straight from an Otii Arc and measuring current consumption. I'm running MbedOS 5.11.2. When I ...
7
votes
2answers
2k views

How does a bathroom scale automatically power on when I step on it?

When I step on a bathroom scale how does the circuit turn on? I've disassembled these types of weight scales looking for obvious hardware switches, but none exist. I suspect the ADC is configured to ...
7
votes
4answers
7k views

RF Wakeup - Battling power consumption

I am currently using two nRF24L01+ (2.4 GHz RF transceivers) together with two AVRs to create a keyless entry system. My problem is battery lifetime when using a CR2032 battery to power the key. The ...
7
votes
2answers
5k views

USB / Battery Switchover Circuit

Background: I am a non-EE (an 0x11? :^) thrust into the world of embedded systems design. I started this project with a only college physics-level understanding of circuits, but I'm gradually learning....
7
votes
4answers
5k views

Efficient low-power buck (step-down) regulator IC for Li-Ion - 3.3V conversion?

It's not easy for electronics novice to find good element base, so I hope this suitable question. Requirement: Efficiently power a lean, 3.3V-based MCU design from a Li-Ion battery. "Efficient" ...
7
votes
2answers
193 views

Eliminating micro current flow

I've built a RAM expansion cartridge for my VIC-20 computer. It uses the CY62256L 32KB SRAM chip. It has been working fine except there's a quirk. If I power off the computer, but leave the ...
7
votes
2answers
4k views

Bluetooth power saving mode for ArduinoBT

I'm trying to get my ArduinoBT to be a bit more power friendly, I have it running in a sensor network and it is constantly drawing power. I want to be able to turn off or put the Bluetooth module to ...

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