What's your favourite flavour of 1.5v to 3.3v boost converter? - Page 1
Forum section: electronics / projects

author: squarefrustration
author_rank: Newbie
timestamp: September 30, 2020, 01:58:19 pm
content: I'm working on a small, low current(<1mA average, 10mA peak pulse) LED+Buzzer ornament project using an attiny1604 and flickering 0805 LEDs.I've made ornaments using a 3V CR2032, but peak current from generating tones will surely degrade it's overall capacity.The plan is to use a single 1.5v AAA cell.I started the design using an MCP1640 because I like the size of the sot23-6 and price point.I'm curious as to what other people's "go to" chip for projects that use a single 1.5V cell?

author: I wanted a rude username
author_rank: Frequent Contributor
timestamp: September 30, 2020, 10:24:13 pm
content: Whichever cell architecture you go for, be sure to include a large bulk MLCC across the power source ... 10 uF or more. These days 47 uF is not expensive. This will decrease stress on the cell, extending its life.The eye's brightness response is logarithmic. A LED PWMed to 10% draws 10% the power but looks 50% as bright.Piezo buzzers are efficient, usually drawing < 1 mA.Knowing this, a CR2032 may run for hundreds of hours, without the inefficiency of boost conversion. But of course over that time the voltage will drop to where it can't run blue/white LEDs ...

author: opampsmoker
author_rank: Regular Contributor
timestamp: October 01, 2020, 11:57:27 am
content: heres one by ricohhttps://www.n-redc.co.jp/en/products/dc-dc-switching-regulator/spec/?product=r1210The way to find loads...is put "MCP1640" into digikey search.Then look what title digikey puts mcp1640 under.Then do a general search of that title.Then filter it to get all the "single output" ones, and "SOT23-6" or "SOT26" or "SOT23-5" ones....then filter the results to put "minimum Vin" first.Then you'll have a big choice before you.If you want to be really "logistical"...then put the part number you choose into a findchips.com search...and pick the one that has the most in stock on all the distys listed on findchips.com...then you'll not likely suffer nil-stock issues.----------------OK ive just realised your mcp1640 is voltage output regulated....so youll need to put a sense resistor in there and use that for current feedback instead, as your load is a led.----------------MIC2287 is a boost led driver from vin=2v5...So you could do my search technique based on this one, and refine it to <2v input.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: October 01, 2020, 06:23:57 pm
content: Heh... last time I did that it was a single transistor blocking oscillator. Otherwise known as a Joule Thief. Don't have any better suggestions offhand, but it's worth putting out there as an option when only very loose specs are needed.Tim

author: mariush
author_rank: Super Contributor
timestamp: October 01, 2020, 08:03:33 pm
content: For this specific circuit, a plain simple voltage doubler IC that can start at 1v and higher would work.For example TPS60301 :https://www.digikey.com/en/products/detail/texas-instruments/TPS60301DGSRG4/11539117datasheet here :https://www.ti.com/lit/ds/slvs302b/slvs302b.pdfworks from 0.9v and has 2 outputs, one unregulated 2 x Vin up to 40mA and one regulated 3v outputAnother option may be TLV61220 :https://www.digikey.com/en/products/detail/texas-instruments/TLV61220DBVR/3458113It may be cheaper in volume, but when you add up the inductor you get to about the same price

author: squarefrustration
author_rank: Newbie
timestamp: October 02, 2020, 02:27:37 pm
content: Quote from: T3sl4co1l on October 01, 2020, 06:23:57 pmInteresting! I've played with a few joule thief's for LEDs but never thought to power anything "smart" like a microcontroller. I'm guessing one could use some sort of zener clamp for very basic regulation at the microcontroller's VCC pin.Thanks for all suggestions. I like that the TLV61220 solution also removes the need for an inductor, albeit with the need for some more caps which are essentially free at QTY (then again, what isn't? haha).I'm going to dabble with a hand full of these solutions on the bench and figure out what to commit to before routing into my pcb, thanks!

author: mariush
author_rank: Super Contributor
timestamp: October 03, 2020, 08:45:19 pm
content: Quote from: squarefrustration on October 02, 2020, 02:27:37 pmTPS60301 doesn't need inductor, as it's a charge pump.TLV61220 does need an inductor, but it's fairly cheap, around 30 cents in 50-100pcs, and 15-20 cents in 1000pcs

author: rvalente
author_rank: Frequent Contributor
timestamp: October 04, 2020, 11:26:07 am
content: MCP16521https://www.microchip.com/wwwproducts/en/mcp16251

author: EverydayMuffin
author_rank: Regular Contributor
timestamp: October 04, 2020, 02:22:45 pm
content: Monolithic Power Systems (MPS) MP3120?https://www.monolithicpower.com/en/mp3120.html

author: Zero999
author_rank: Super Contributor
timestamp: October 04, 2020, 06:15:11 pm
content: Quote from: squarefrustration on October 02, 2020, 02:27:37 pmIt's possible to add another transistor, which cuts off the blocking oscillator, when the desired output voltage is reached. It's not very efficient and the output isn't very clean, but does the job. Here's an example of a using a regulated Joule thief before a low-dropout linear regulator, to give a clean DC output. If you're more bothered about efficiency skip the linear regulator and add more filtering, in the form of an inductor, resistor, capacitor and ferrite beads.https://upload.wikimedia.org/wikipedia/commons/thumb/2/26/Regulated_Joule_Thief_generalization_and_cleaning.svg/1024px-Regulated_Joule_Thief_generalization_and_cleaning.svg.png?1601835008959https://www.wikiwand.com/en/Joule_thief

author: bson
author_rank: Unknown
timestamp: October 04, 2020, 07:47:39 pm
content: I've had good luck with theTI TPS610986DSER. Super simple, just works.

author: nuclearcat
author_rank: Unknown
timestamp: October 05, 2020, 03:03:15 am
content: Quote from: rvalente on October 04, 2020, 11:26:07 amMaybe MCP16251?

author: nuclearcat
author_rank: Unknown
timestamp: October 05, 2020, 03:13:11 am
content: Quote from: bson on October 04, 2020, 07:47:39 pmCan't say it is simple or cheap, it looks like niche(50mA only and very strange VSUB voltage), but it is really interesting one with it's dual output and passthrough!

author: bson
author_rank: Unknown
timestamp: October 06, 2020, 12:18:31 am
content: Running off a single 1.5V cell is rather niche to begin with. The voltage sags from 3.3 to 3.25V or so around 100mA, but that's not really a problem. Especially when you typically only need 1-10mA.