Jellybean DC/DC buck - Page 1
Forum section: electronics / general

author: 0x4A47
author_rank: Newbie
timestamp: February 13, 2025, 12:50:56 pm
content: Some time ago, Dave made aTop 5 Jellybean regulators and referenceslist -https://www.eevblog.com/forum/blog/eevblog-1438-the-top-5-jellybean-regulators-references/This got me thinking, what about DC/DC buck converters? They are getting more and more common these days. Are there any go-to "jellybean" buck regulators that everyone keeps on hand ? Which ones would make your top 5 and why?

author: tom66
author_rank: Super Contributor
timestamp: February 13, 2025, 02:58:49 pm
content: Too many variations now, as the field is still evolving.I've designed MP28167A into a lot of products because it can be programmed over I2C. Bad thing is it is fixed address so you end up with bus multiplexing or otherwise to talk to more than one. Its inbuilt telemetry over I2C is useful.TPS54331 is a good simple non-synch buck in a SOIC8 package.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 13, 2025, 03:28:36 pm
content: Please avoid "jellybean" thinking. That led to disasters like 1117 regulators everywhere, which could have been avoided if designers chose parts based on distributor availability, pricing, and technical features instead of a "feeling" of something being popular and using the same shit part for 20 years longer than necessary.In other words: just go to Digikey/etc. and look what DC/DC buck regulators they have available. Surprisingly you will find out that many cheap parts e.g. in 6-pin SMD packages have second source (and third) options which do not necessarily share part numbers but share a pinout: easiest way to find them is to filter by package and see what package is most popular (in number of parts). More honest than the world of incompatible 1117's sharing part number but not stability characteristics.

author: 0x4A47
author_rank: Newbie
timestamp: February 13, 2025, 04:17:20 pm
content: I've already done some looking around and found a few that share the same SOIC-8 pinout:MP2307, MP1484, RT8293A, AP6502, RT7257E, TPS54336A.However, SOIC-8 is a pretty big package for general purpose stuff these days, some of these are already obsolete, and I'm unsure how long the others will remain in production. Additionally, there are some differences in their specs. Some use a 0,8V reference, while others use 0,925V, and their switching frequencies vary between 340kHz and 480kHz.I was secretly hoping for a compiled list of more or less interchangeable parts that could serve as drop-in replacements for one another. But I guess I'll have to do some digging around for it.

author: 0x4A47
author_rank: Newbie
timestamp: February 13, 2025, 04:46:22 pm
content: I was able to compile the following 2 lists:VIN< 5,5V:TLV62568, TPS62A0, AP3401, RT8096CVIN> 5,5V:LMR51420, AP6220x, TPS56220x, TPS56120x, RT6252I have not yet checked if they're compatible across all their specifications, but they share the same package and pinout, and at first glance them seem compatible.

author: Siwastaja
author_rank: Super Contributor
timestamp: February 13, 2025, 06:10:28 pm
content: Quote from: 0x4A47 on February 13, 2025, 04:17:20 pmYes it is, and others having noticed that too and prefer smaller parts for low power (and larger QFN stuff for high power), making the SO8 offerings slowly go obsolete.Take a look at smaller 6-pin SMD packages.QuoteThat's pretty easy to manage - just change a resistor when you change the IC. Also 340 vs 480kHz isn't a big deal, then again going between 300kHz and 1.5MHz part is a bigger one.Still, this isn't any worse than needing to swap capacitor types (tantalum vs. MLCC, possibly package size/footprint) when second-sourcing The Good Old 1117.

author: mariush
author_rank: Super Contributor
timestamp: February 13, 2025, 06:43:03 pm
content: Diodes Inc. has a ton of regulators that have the same pinout, or similar pinout... and they're also available on LCSC and lots of distributors cheaply.I like the datasheets as they have suggested layout, they have recommended component values, I find the datasheets easy to read by beginners.AP61xxx series : 2.3V-5.5V in, 0.6V-3.6V out, 1A or higher ...exap6110x (1A) :https://www.digikey.com/short/3z5ddnvzap6120x (2A) :https://www.digikey.com/short/3vt3d3p4ap6130x (3A) :https://www.digikey.com/short/h9fvf7zwAP62xxx series : 4.2v to 18v in, up to 7v out, 1A or higher versions :https://www.digikey.com/short/wzqj7j32AP63xxx series : 3.8v to 32v in, up to 31v out, 1A or higher :https://www.digikey.com/short/q575h0zqThis series also has fixed output versions for 3.3v and 5.0v output.AP64xxx series : 4.5v to 40v in, from 0.6A to 5A output :https://www.digikey.com/short/1fc4t2tw, includes SOIC packages... some versions have configurable switching frequency, some versions are fixed frequency and repurpose the frequency pin to set soft start functionality, some versions have built in compensation so the compensation pin is repurposed with soft start feature... basically you can use same footprint and circuit with multiple versions of the same chip and you just not install components on the board if the version of the chip you use lacks that feature.Texas Instruments parts also have good datasheets and there's also Webench free system that let's you test circuits or get recommended part models.Ti chips :https://www.digikey.com/short/4hjh2qrvTPS62A01 (1A) and TPS62A02 are super cheap, TLV62568 is also nice chip ... these are for 5.5v or lower input voltageTPS562xx and TPS563xx series for up to 17v in, up to 7v out, 2-3A out...TPS562xxx (2A) :https://www.digikey.com/short/t58tj4frTPS563xxx (3A) :https://www.digikey.com/short/pcfqjbv7LMR51xxx series for higher voltages, and lowish currents (0.6-1A) :LMR51606 is a good option, up to 65v in, up to 600mA out, and it's available in two versions - X goes at 400 kHz , Y goes at 1.1 MhzX (auto pfm/pwm)https://www.digikey.com/en/products/detail/texas-instruments/LMR51606XDBVR/22116882Y (auto pfm/pwm)https://www.digikey.com/en/products/detail/texas-instruments/LMR51606YDBVR/22116848XF (forced PWM)https://www.digikey.com/en/products/detail/texas-instruments/LMR51606XFDBVR/22116849YF (forced PWM)https://www.digikey.com/en/products/detail/texas-instruments/LMR51606YFDBVR/22116862Forced PWM is less efficient at very low current, more efficient at higher output currents.LMR51406 is the same, only goes only up to 42v in :https://www.digikey.com/short/d408jbhwand if you want more current, there's the 1A versions LMR51410:https://www.digikey.com/short/n4j4mtm0I like Richtek but I found that they like to have COMPensation pins on most synchronous rectifier regulators and I'd rather pick regulators from companies that have that compensation built in, just don't want to have to keep looking in datasheets or to calculate what resistor and capacitor to put on the compensation pin to get the chip stable.edited to correct small typos

author: tom66
author_rank: Super Contributor
timestamp: February 13, 2025, 07:50:46 pm
content: Richtek has clones of nearly every older TI buck. The company I used to work for would build prototypes with TI parts then progressively swap these out for Richtek. Usually it would work with almost no changes, sometimes we'd have to add/remove a filter cap or change an inductor, but in the end all that mattered is the accountants liked the fact that we were saving £/€/$2 per unit.

author: SiliconWizard
author_rank: Super Contributor
timestamp: February 13, 2025, 11:49:31 pm
content: Diodes Inc parts are fine, Richtek as well. TI parts are usually good but a number of their switching converters have various nasty issues - make sure to look up the particular reference you're interested in, to see if it's being talked about on TI forums. I also have never had a problem with MPS converters (https://www.monolithicpower.com/en/products/power-management/switching-converters-controllers.html).That's for vendors. Of course, a "jellybean" buck converter doesn't mean much as there are just too many parameters (and thus variants) depending on your use case: quiescent current, efficiency at various loads (for your use case), switching frequency (fixed or not), the ability to synchronize them to an external clock, max output current (for your particular Vin/Vout combination), compensation, internal or external power FET, and so on...