Powering by 1*AA battery

[001]

Hi!

I see lot of calculators use single AA/AAA battery
What the right way to boost 1.2V to 3.3-5V for MCs?
Can You post some standard circuit (built-in NiMH charger will be ok too)?


Thanx

[ogden]

Check datasheet of TI TPS6126x. Also ON Semiconductor offers pretty popular boost converter IC's for single alkaline/nimh cell.

[Dave]

Calculators use ASICs (the black blob in the middle of the PCB) that are designed to use the wide-ish voltage span of the single alkaline battery directly.
I know this isn't a solution to you, just wanted to share a tidbit that you might find interesting.

[NivagSwerdna]

MCP1640 Single Quadruple-A Battery Boost ... - Microchip
Googled gives a nice reference design with low Iq
A couple of years old but I like it.

[james_s]

There's an open source project called the Backwoods Logger that runs months on a single AA or AAA battery. Have a look at that for an example of a boost converter. I don't remember what IC it uses but I built the AAA version years ago and it runs a very long time.

[mikeselectricstuff]

MCP1640 Single Quadruple-A Battery Boost ... - Microchip
Googled gives a nice reference design with low Iq

Beware the Iq specs on these ICs - it is usually sourced from the boosted output, so draw from the battery will be multiplied by the step-up ratio. Not usually an issue for cylindrical cells though.
 

[mariush]

Go to any distributor of electronic components and select switching regulators, then filter results to show BOOST or (step-up) regulators, and then further filter to show only the ones that can operate with MINIMUM VOLTAGE  below your single battery voltage, for example 1v or less.

From there, you choose a regulator based on how much current your product will use - for example if your microcontroller project won't ever consume more than 50mA, then you could choose a regulator that's designed to output maximum 100-150mA.

Here's a starting point:  https://www.digikey.com/short/j1105q


However, you'd still have to check the datasheet and see graphs and charts, because for example you'll find such regulators that can start and function with low voltage, but the output voltage will depend on the input voltage level - below 1v, the chip may only output up to 3.3v, and from 1v and higher, the chip may output 5v

Here's an example: MCP1640 from Microchip : https://www.digikey.com/product-detail/en/microchip-technology/MCP1640T-I-CHY/MCP1640T-I-CHYCT-ND/2258621

On 1st look, it's a chip that can work from 0.8v and can output up to 350mA... but, check the datasheet : http://ww1.microchip.com/downloads/en/DeviceDoc/20002234D.pdf

You can see on the first page that it says :   Up to 96% Typical Efficiency  and Iout > 100mA @ 1.2v Vin , 3.3v Vout ... but there's no  1.2v Vin and 5v Vout  so you can scroll down and on page 5, you'll find Figure 2-6 , 5.0v Vout Efficiency vs Iout and there, you can see that the black solid line that represents 1.2v cuts at 100mA ... so with just 1.2v input, the chip can't output more than 100mA at 5v.  You can also see that it's not quite 96% efficient at such big voltage difference, with just 1.2v it's the most efficient at around 30mA output, and at that point it's around 82% efficient.

You have example circuits on the 2nd page in that datasheet, and you can read the datasheet to understand more about how the chip works.

[DaJMasta]

As mentioned, the micro used also can have a built in boost converter, and there are a number of general purpose micros for low power use that have an integrated low power boost converter, but the broadest range of options is going to be in dedicated boost converter ICs.  You will typically need a handful of passives and maybe a diode other than the IC itself, but you can select something optimized for your expected current draw for best efficiency.

[Nauris]

There are also microcontrollers that work straight from AA battery voltages, for example Lapis ML610 series work down to 1.1 V.

[wraper]

You can simply use MCU that can be powered from a single cell directly https://www.silabs.com/Marcom%20Documents/Resources/C8051F9xx-media-presentation.pdf

[Kasper]

+1 for Mariush.
Never trust the specs on the first page of the datasheet. A boost regulator will probably not deliver its max current when fed with its min voltage.

If you find a regulator that can boost from 1V to 3V and output >200mA, let me know.

[ogden]

There are also microcontrollers that work straight from AA battery voltages, for example Lapis ML610 series work down to 1.1 V.

Right. There's MSP430L092 going down to 0.9V (w/o booster) as well. AFAIK this is one chip out of whole msp430 family with such voltage specs.