Boost IC recommendations?  - Page 1
Forum section: electronics / projects

author: Things
author_rank: Regular Contributor
timestamp: May 17, 2015, 11:40:12 am
content: I was hoping maybe I could get a few pointers from people here about a suitable boost IC for use in my project.Basically I'm looking for something that'll give me around 500mA at 5V, from a single LiPo cell input. Preferably with active low shutdown pin (Gnd = off), and load disconnect, but I guess I can implement those manually if I have to. Finally, I need a hand solderable SMD package - basically anything with pins out the side is fine. I've been trying to use the parametric search on TI but given I'm looking at integrated switch IC's, I'm not really sure how switching current corresponds to output current.Any suggestions?

author: Paul Price
author_rank: Super Contributor
timestamp: May 17, 2015, 02:18:14 pm
content: Micrrochip MCP1640 or TI LM27313 will do the job..SOT-23Sorry..I thought iI read 300mA for the above, the above do only approx. 350mAThe MCP1642 8-pin MSOP does the job for $1.15 a pop.The LTC1308 in SOIC and at $7 a pop, doe the job.

author: PeterFW
author_rank: Frequent Contributor
timestamp: May 17, 2015, 02:46:36 pm
content: Quote from: Paul Price on May 17, 2015, 02:18:14 pmWould have been my recommendation as well but it will only do 350mA if the cell is fully charged and at 3.7V only 300mA if memory serves correctly.

author: jt
author_rank: Regular Contributor
timestamp: May 17, 2015, 03:15:24 pm
content: I find the Digikey filters work best for finding regultaors. For your case:Digikey -> Products -> PMIC - Voltage Regulators - DC DC Switching Regulators (or link below)http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-voltage-regulators-dc-dc-switching-regulators/2556570Then work through the filters. Generally the order I would go with is this (hitting apply filters after each selection to reduce the list sizes)1. check the in-stock option2. select surface mount3. select manufactures I like (TI and Linear at top of the list for power management devices, although several other good ones out there too).4. select type -> step up (boost)5. number outputs -> 16. output current -> select everything higher than your minimum7. select all the package types you are willing to work with (anything leaded in your case)8. select input and output voltage constraints (this can be tedious, so do everything you can to constrain the selection first)With the preceding, I get 190 options. I'm linking the filter results below - but I'm not sure if the link requires locally cached information to bring up the correct results.http://goo.gl/UF47JgIf you are price conscious you can sort by price, but if you are interested in only small-quantity buys, first filter out tape-and-real packaging options. Otherwise the lowest prices will be dominated by 3000 min buy offerings.At this point you have to start clicking through data sheets to find the other features you want. I'd also look to make sure the efficiency curves make sense for your given load profile if you are power conscious. Without doing this, I found the Linear Tech LT1306 as a possible candidate. It doesn't look like it has an active low enable, but I'm sure there are other options that do.

author: mariush
author_rank: Super Contributor
timestamp: May 17, 2015, 03:27:47 pm
content: If price is not a big factor, see LT1308 :http://cds.linear.com/docs/en/datasheet/1308i.pdfShutdown feature, battery checking features (low battery indicator, detector etc), good efficiency etc

author: Paul Price
author_rank: Super Contributor
timestamp: May 17, 2015, 07:37:58 pm
content: I know this is unusual, but it just might work!Parallel two MCP1640's pin for pin.Assume one of the two starts before the other, the current in the inductor slowly begins to rise.Some nanoseconds later the second 1640 turns on. Now the current through the inductor can reach twice the current limit of the one 1640 alone. At a sooner point the first 1640 turns off..it has reached its current limit..the second 1640 may be close to reaching this limit as well. As soon as the first 1640 turns off, the second is now instantly turned off by the excess current, but the total amount of energy in the inductor has been doubled.The MCP1640 can be bought for $.47 so two for a buck, that;s better than $7 a pop and you get at least 700mA of current to the load.

author: Neverther
author_rank: Regular Contributor
timestamp: May 17, 2015, 08:10:19 pm
content: SP6641B, no load disconnect but what do you expect from sot23-5. Haven't had problems but I do not run them at the rated 500mA.500mA at 3.3V input. What is the startup load like? (or with separate load disconnect just power it up first?)1.44$ at digikey, stock has always been issue but there seems to be 400 in the bin at the moment.

author: paulie
author_rank: Frequent Contributor
timestamp: May 17, 2015, 11:36:14 pm
content: Here's ready to go boost converter modules that run off single alkaline, nixx, or lithium AA cell for 50 cents each:http://www.ebay.com/itm/5pcs-PFM-Control-DC-DC-0-9V-5V-to-USB-5V-DC-Boost-Step-up-Power-Supply-Module-/121650163430?pt=LH_DefaultDomain_0&hash=item1c52ea2ee6Probably about 1/10 the cost of designing from scratch. Not to mention the many hours spent debugging. Surprising how many internet suggestions feature the most complicated and expensive options. Even more amazing how often these are preferred over lowest cost, most efficient, and simplest solutions.

author: Marco
author_rank: Super Contributor
timestamp: May 17, 2015, 11:52:30 pm
content: Paulie, those have an external Schottky ... they don't have load disconnect.I just now searched digikey for boost and got all the results from the switching regulators (this is faster than selecting all the various permutations of boost functions) and selected for synchronous, picked all output currents higher than 500ma AND "-", selected quantity 1 and sorted by price ... didn't bother with package selection, too much work.Thesewere the results andthiswas the 11th entry.PS. why did multiple people mention the MCP1640 ... but didn't think to just check if Microchip had a higher current version, cause they do ... the MCP1642, which I just noticed slightly further down the list. The PAM2401 is a bit cheaper though in singles.

author: paulie
author_rank: Frequent Contributor
timestamp: May 18, 2015, 12:15:50 am
content: OP did not demand load disconnect but I will admit not being familiar with that feature or understand the purpose. There are some Ebay versions with similar pricing that do not have external schottky but not sure that means load disconnect. I do know enable is useful and the half dozen types I have worked with all have that ability and very low idle current.

author: PeterFW
author_rank: Frequent Contributor
timestamp: May 18, 2015, 05:46:53 am
content: Quote from: Marco on May 17, 2015, 11:52:30 pmWhy? Because it is low power efficient, wich is important to me, when something runs of a battery. The MCP1642 is not.