power bank boost modules confusion - Page 1
Forum section: electronics / beginners

author: littlebill
author_rank: Regular Contributor
timestamp: December 21, 2024, 03:31:41 am
content: So I have designed what I thought was a nice power bank. couldn't be farther from the truthI am using xl6009 boost modules from Ali express. at 4 amps with heatsink in ambient they are on fire. Thus I learned about droop resistors and diodes to parallel them (i'm not going backwards at this point)what i don't understand is these modules are on fire at 2 amps, with heat sinksyet this module, which boosts from 3.2 to 12v has no heatsinks and can do 18 watts 1.6 amps sits at 150f with no trouble.https://www.aliexpress.us/item/3256807046636114.html?spm=a2g0o.order_list.order_list_main.65.dd6b1802HlJIWJ&gatewayAdapt=glo2usathis module is also similarhttps://www.aliexpress.us/item/3256805954269849.html?spm=a2g0o.order_list.order_list_main.206.dd6b1802HlJIWJ&gatewayAdapt=glo2usa150F at 14 watts.Can someone tell me why? is it simply better IC's? newer technology. After seeing the difference between a fake mosfet and a real one, its clearly a parts thingbut I have search for multiple hours and I am not finding any kind of module (no interest in full design) that even comes close to rivaling these. and some of the pd boards go up to 100w, with no heat sinks to be seenI really hope someone gives a real answer, the amount of hours on this and cost at this point is making my hair grey.

author: Whales
author_rank: Super Contributor
timestamp: December 21, 2024, 05:30:59 am
content: I have never heard of the XL6009, but they look very similar to the common LM2596/LM2576 used on a lot of cheap boost and buck boards. Notable differences: pinout, higher operating frequency, has OVP and seem to be FET-based. Diagrams for internal control loops look quite similar.QuoteBe warned that the "4 amps" refers to the switching current limit, not the output current of the whole converter. When using these chips as boost converters the internal switching current will be MUCH higher than the output current. You're probably already running them past their 4A maximum ratings even at a 2A output level.Greymarket Aliexpress sellers will not understand this and will instead market them as 4A output or just "4A" performance.QuoteYes. Not only the quality of the switcher chip but also the parts you use to accompany it (diodes, capacitors, external mosfets), the layout of those parts and other design choices made (different switchmode toplogies). Efficiency easily ranges from 50% to 98% across many common designs, and this efficiency also depends on their usage scenario (input V, output V, load).I generally do not expect anything that uses the TO263 package to be particularly good. They're cheap and easy to get (because the LM2596 market has so many clones) and I use them quite a bit for random prototypes but I never expect their efficiency or noise ripple to be particularly good.

author: littlebill
author_rank: Regular Contributor
timestamp: December 21, 2024, 03:29:24 pm
content: so do you have a recommendation for a boost module?

author: littlebill
author_rank: Regular Contributor
timestamp: December 22, 2024, 03:41:43 pm
content: Does really no one have a single recommendation? I feel this would be a common request?

author: Whales
author_rank: Super Contributor
timestamp: December 23, 2024, 12:05:29 am
content: There is no one good design. There are dozens of different variables involved, any choice of which is a compromise between:* cost* efficiency* load* stability with different load types* ratio between input V and output V* output ripple* noise emissions* sourceability (many switchmode chips are short lived in the market)* safety (OVP OCP)* ease of solderingWant cheap and don't care about anything else? Use a MC34063.Want everything? You can't have cheap, you'll spend hundreds of dollars on one chip or board.If you're willing to design your own circuit then checkout TI's powerbench website, you can input some numbers and it will give suggestions. Also checkout common parts on Digikey and LCSC, read their datasheets and see if you like any.If you only want pre-made modules: understand the difference between "max switching current" and "output current", then buy something that exceeds your specs and try it out.

author: LooseJunkHater
author_rank: Frequent Contributor
timestamp: December 26, 2024, 12:06:53 am
content: Quote from: littlebill on December 22, 2024, 03:41:43 pmWhat is your input voltage? Output voltage + current? Output voltage noise max (if important)? Type of load? Is over-current protection (OCP) or overtemp protection (OTP) needed?Not sure how anyone can help suggest/recommended products without more details, but as the other posted said, the more specific/niche features you need, the more expensive it gets and leads to you more likely needing to custom-design a PCB (or steal an existing design).There's no universal buck/boost converter to recommend. Some have low idle current consumption, synchronous, create negative voltages, support 100v+ input voltages, and so much more.