Tagged Questions

"low-power" refers to components and circuits which are designed to have a lower power consumption than their common counterparts. This is most often a requirement because of limited available power, as in battery operated devices.

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29 views

Low power Cmos Op-Amps

I recently designed a 2 stage micro-power op-amp in Cadence Virtuoso with an open-loop gain of 36dB. I checked the voltage swing in open-loop and got a full swing from 350mV to -350mv for a dual power ...
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2answers
82 views

How to start LED wirelessly in a very compact and cheap module?

I have been thinking and researching about this issue for a while with no success. I am hoping someone can solve this problem in the community. I want to have many small modules each with a small ...
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0answers
41 views

Low Accuracy GPS/Low Detection (e.g. detect country or state)

I'm making something to go with an electronic compass so I can always point to a certain (non-true north) location. To do this, I want to detect what state the user is in, and look up an approximate ...
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2answers
24 views

how many 74LS low-power Schottky inputs can an output of MC9S12DG128 drive?

I need to figure this out for a project and can't seem to find the answer. Does anyone know how I can figure this out? I think there is an equation to find this and can't seem to find the ...
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2answers
49 views

Prevent loss of Large Signal Voltage Gain at low Rload

Operational Amplifiers (opamps) have the tendency to drop their Large Signal Voltage Gain when the load is too low. This behaviour is usually described in the datasheet. Loads of 500 ohm and lower ...
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3answers
50 views

Is it detrimental to an SMPS to turn it on and off frequently?

I've got a 5V SMPS powering two separate servos: and The smps is a tps562200 The application is an autonomous sail boat (3 feet long). One's a winch, the other a rudder. I have code that scans ...
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2answers
69 views

Measuring power consumption of a design ranging uW to tenths of mW

I want to measure the power consumed by my design ranging from uW to tenths of mW. Power values I wish could be recorded digitally so that I can use them for analysis later. May be another form is ...
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2answers
63 views

Capacitor leakage and design for low energy battery powered devices

For the design of a portable battery operated device, I have some power circuitry which requires a DC-DC converter and some other regulators, battery charger IC etc. While in the process of ...
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2answers
112 views

Operating an ATmega328P-PU at 2.5V

For my job, I was tasked with creating a board to interface with a 2.5V device we've made. So, to keep things simple, I decided to interface it with an ATmega328P-PU running the Arduino firmware at ...
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2answers
83 views

Looking for efficient battery supply to power 3.3V circuit

I have been searching everywhere for the best way to power my circuit and I can't find straight forward information. My circuit needs 3.3V and the maximum current it draws is 50mA. It will run at ...
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4answers
61 views

Options for semi-permanent memory in a low-energy setting

(Hopefully this will be broad enough to be on-topic.) I'm looking for options to store several megabytes of data over the period of a few weeks in a coin-cell powered application. The data doesn't ...
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1answer
66 views

Prevent EPROM powering from IO pin

I consider using a cheap Microchip 3-pin EPROM with single bidirectional data line as ID storage on various daughter boards. Since I don't want to waste daughter board connector pins on a device ...
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2answers
91 views

Opening MOSFET's gate with low voltage PWM

I have PWM of very low frequency and very low duty cycle. And max voltage comes out are 3.3. But thats not enough to open the MOSFET's gate(IRFP250N). Now I want to amplify the voltage. I do not have ...
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2answers
43 views

Low power ripple pulse counter

I'm trying to find a ripple/pulse/edge counter chip that can record rising edges from a wind anemometer while my AVR sleeps. The signal is typically 0-50 Hz. I want to read it every 10 minutes, so it ...
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0answers
43 views

Why would a buck regulator continue to draw current when EN was off?

I've got a board with two regulators on it a TPS62125 (to power the whole board) an LM2734 (to power servos) For the purpose of this test, the EN pin of the LM2734 is pulled down to ground with a ...
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0answers
86 views

STM32F030 RTC wakeup from stop mode

I'm writing an app, that most of its time will spend in STOP or STANDBY mode (battery powered microsystem). I'd like the internal RTC to wakeup my STM32 every 5 minutes, enter the ISR, do its tasks in ...
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10answers
2k 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 ...
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3answers
181 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 ( ...
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1answer
69 views

Shutdown mode in si4010 microcontroller

I'm working on a project with si4010 microcontroller plus a battery and I want to save power, so I have to enable the shutdown mode. I need to wake up every 1s and do the process and then go back to ...
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4answers
89 views

Very low-quiescent (<2mA), 5V, simple “speaker” driver

How can I drive a 30ohm speaker from a 5V microprocessor in a simple, very low quiescent-current (<2mA) manner? The "speaker" is actually a coil, not a speaker - and I'm trying to induce a ...
3
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4answers
386 views

What are some of the segmented displays with the lowest power consumption?

I have to select a low-power display for a solar-powered digital clock. I have looked into numerous technologies, including e-ink. However, I was still unable to compare between them due to the lack ...
2
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1answer
151 views

PIC32 sleep mode with watchdog wakeup failing

I am in the process of trying to get a PIC32MX795F512L to run with lower power consumption. I'm trying to get it to enter sleep mode and then be woken by the watchdog timer. All pretty standard ...
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0answers
71 views

powering a micro in sleep mode

I've got a setup that will spend 1/3 of its time running a few servos (figure up to 1A @ 5V), 1/3 running sensors / other (<300mA @ 3.3V), and 1/3 of its time sleeping with just the watchdog ...
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2answers
69 views

Is it safe to not power this USB to I2C chip when USB isn't plugged in?

I am working with someone on a data logger based on an MSP430. Since it operates on battery power, we want the device to use as little power as possible. We are planning to use this chip (FT201X) to ...
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2answers
251 views

ATmega328P running on CR2032 has issues with timing/sleep code as voltage depreciates over time

I have an ATmega328P running at 16 Mhz on CR2032 with a few sensors and radio for about a week now. It started out at 3+ Volts and is currently measuring at 2.96 Volts. At present, I am not using ...
2
votes
1answer
120 views

calculating total power consumption with LDO vs switching regulator

I'm just getting somewhat familiar with voltage regulators and am trying to make sure I'm understanding a bunch of parameters correctly. Scenario: I have a project that spends 1/3 of its time ...
2
votes
3answers
138 views

What happens when current sourced from a switching regulator goes too low

On the recommendation of an SO-er, I'm looking at using a TPS54295 to power a controller that uses an ATMega 2560. The regulator will be powered by a 3-cell LiPo battery, implying input voltages ...
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3answers
139 views

Multiple voltages off a single source

I'm building a controller for project that has hobby servos. These typically need ~5V to run. The controller will be an ATmega 2560, running at 3.3V / 8MHz. Looking at the reference design for the ...
0
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1answer
202 views

Reducing current consumption in deep sleep mode

This is in relation to the question I asked about deep sleep mode. I'm using PIC18F and it says in the datasheet that in deep sleep it would consume only few nA. But when I configured for deep sleep ...
3
votes
2answers
133 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 ...
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5answers
290 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 ...
2
votes
1answer
86 views

What kind of solar panel is required to keep a mobile alive forever?

I want to build a webcam from an old mobile and I want it to be solar powered. The phone use a 3.7V lithium-ion battery of 1500mAh capacity. The phone last 24h hours on one charge. So if I'm right, ...
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2answers
147 views

How long will this low duty 555 LED blinker last on batteries?

I know there are many questions about LED blinkers, but I haven't yet found a clear answer for this. I have a 555 circuit blinking a blue led (or three in parallel). I has a low duty cycle (using a ...
4
votes
3answers
205 views

Using timer to power on/off a high current circuit

I'm working on a Arduino project that takes measurements from the environment and sends them to a remote server over WiFi. The circuit should be battery powered and I've measured that what I have at ...
1
vote
1answer
117 views

Implementing dynamic frequency scaling on PIC32 by changing PLL multiplier/divider?

I read in the PIC32 Reference Manual that one can change the PLL multiplier and divider at run-time, provided that the input frequency is between 4 and 5 MHz and the resulting frequency does not ...
0
votes
1answer
370 views

How to power Raspberry Pi with a Flight Controller

I am making an autonomous quadcopter and I need Raspberry Pi on board to implement image processing. The issue is that I have a 4in1 ESC which comes with only one UBEC to power the flight controller, ...
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2answers
68 views

How to fit back-up battery into the controller board? [closed]

I'm newbie in the field of PCB making and I have one relevant question. I have a controller on a PCB which has many resistor dividers and passive components. I would like to know, if I want to make ...
0
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2answers
53 views

Devices which consume substantial power in modern embedded real-time systems? [closed]

Could anybody cite examples (if any) of devices and peripherals in modern embedded and real-time systems which consume substantial amount of power compared to modern processors. As processors get more ...
0
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2answers
95 views

How to interface a SPST switch with minimal current (1µA)?

The usual way to wire up a SPST switch to a MCU is by means of a pull-up resistor. However, this wastes current when the switch is closed. If this switch is used to wake up the MCU from sleep, then ...
1
vote
1answer
233 views

Preventing parasitic powering of FT232RL by ATMega328P

I have a battery powered board with an ATMega328P and some other peripherals such as SD card, RTC, sensors, etc. The design of the board is to be as low power as possible, whilst keeping with the ...
1
vote
0answers
84 views

Can BJTs operate in the nano-ampere range?

Can BJTs can operate predictably with very low currents, in the order of nano-amps or less? I am involved in microelectronics design and have made a voltage reference chip that is MOSFET-only and ...
2
votes
2answers
84 views

low power displays

What kind of displays can I use effectively with a coin cell battery (CR2450)? The backlight or the entire display would be on only when necessary. From previous answers I know that a liquid crystal ...
1
vote
1answer
135 views

Latch power on-off circuit

See the circuit below: I am trying to make a shutdown circuit for a low power application. Basically, I want the system to be able to be turned on by a button push, and then turned off by a ...
0
votes
1answer
91 views

Low power timer circuit for solar tracking

I'm making a solar based device but it needs to be aligned according to sun's position in sky , the whole assembly needs to move around 11 degree/hr. So I was thinking of using a timer circuit (low ...
2
votes
1answer
189 views

how does a cell phone transmitter work?

I came across a question that is really puzzeling me. I did some basic calculation for a cell phone transmitter. I based on 900Mhz band and assumed a 20Km distance to a cell tower. On top of that I ...
0
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2answers
143 views

Low voltage (<3V) signalling on USB DP/DN - will it work?

I'm using a microcontroller (specifically, the STM32L1) that integrates a USB device full-speed interface. I want to supply it with just 2V VDD, which is within spec for that micro. But that means USB ...
2
votes
2answers
182 views

Unpowered devices on I2C/SPI bus

I'm trying to develop a board that includes I2C and SPI devices that are unpowered for the majority of the time to save power. I found that for these particular devices (Honeywell HSC pressure ...
2
votes
2answers
179 views

What is the tiniest, low-power, and efficient am transmitter?

Here are my constraints: I need to build an am transmitter, but it has to fit in a 1 inch diameter and ~1 inch height box. Since the box is very small, I plan to use a CR2032 battery, which is also ...
0
votes
1answer
145 views

Solar Charge Battery Low Voltage Disconnecting

I have a 4.2V 120mA max solar panel and 3.7V 1200mAh battery. I'm trying to make a solar power system for my arduino. I search through battery management IC's and generally understand the charge ...
6
votes
1answer
2k 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 all the time... like every 4 or ...