In need to replace a JRC or STMicro 317 Voltage Regulator. Which brand is best? - Page 1
Forum section: electronics / beginners

author: zdelarosa00
author_rank: Regular Contributor
timestamp: October 12, 2019, 05:56:01 pm
content: Which brand is best? In my knowledge, the big names that make the part are JRC, TI and STMicroelectronics.I don't know with facts, but my personal ranking in terms of quality/performance(?) would be:1.-JRC2.-Texas Instruments3.-STMicroelectronicsIn terms of brand name, reputation, quality, known facts, numbers, performance of the parts, scope of the usual equipment that has them (demands of the application). But I really don't know what can change from brand to brand talking about exactly the same part, apart from volume and packaging plastic.I really don't see JRC around much though. So maybe I'm biased by popularity.

author: floobydust
author_rank: Super Contributor
timestamp: October 12, 2019, 07:46:48 pm
content: I find a difference between brands, some makes of LM317 and 78xx are very noisy. Fairchild is shit, LT the best but very expensive.If it's a noise critical application, like audio or metrology, measure it with a scope and be prepared for huge differences in quality.

author: floobydust
author_rank: Super Contributor
timestamp: October 12, 2019, 09:50:50 pm
content: Some 1-lot Digikey $USD prices:LT317AT(LT) $4.85LM317BT (ST) $0.64 "single gauge" thin tab TO-220, absolute garbageLM317T-DG (ST) $0.64 "double gauge"LM317T (On-Semi) $0.71 "single gauge" thin tab TO-220, absolute garbageThe limitation is a 3-pin package can't have a bypass cap across the reference. But these IC's spoiled us they are so convenient.The low noiseSuper Regulatorsfrom Walt Jung's work uses low noise op-amps AD825, AD848, AD797 etc. - all expensive.I haven't tried using a cheapo NE5534 or similar with discrete pass transistor.

author: wraper
author_rank: Unknown
timestamp: October 12, 2019, 09:58:31 pm
content: Quote from: floobydust on October 12, 2019, 09:50:50 pmPerformance wise it does not matter. And it's not ON semi only who does this. ST does exactly the same thing. Though you probably should avoid mounting it with a screw and use spring clip instead.

author: floobydust
author_rank: Super Contributor
timestamp: October 13, 2019, 10:34:24 pm
content: There's a thermal performance hit - try it. You won't find thermal data on this cornball package it's that bad.Isn't it strange that the single gauge tab saves 55% on copper but isn't used on anything else but these voltage reg IC's LM317, 78xx. No thin tab DPAK or D2PAK out there. Hmmm.I find the thin tab warps if you aren't very careful with torque tightening the screw. Single gauge it's just garbage all round and the rants on EDN concur.

author: wraper
author_rank: Unknown
timestamp: October 13, 2019, 10:42:03 pm
content: Quote from: floobydust on October 13, 2019, 10:34:24 pmNope, single gauge has the same thermal resistance as usual TO-220 and they are not distinguished in datasheets separately. Also Vreg such as 78xx and LM317 have too low maximum power dissipation for it to matter.QuoteDPAK is already about as thin as single gauge TO-220. Also SMD packages use less metal than TO-220 to begin with. As of D2PAK, there is single gauge.https://www.onsemi.com/pub/Collateral/936-03.PDFQuoteAlso tab and center lead is a single piece of metal, side leads are too while in leadframe. In single gauge package they have the same thickness which certainly makes leadframe production easier and cheaper besides simply saving metal.

author: floobydust
author_rank: Super Contributor
timestamp: October 14, 2019, 05:32:22 am
content: The thermal research is purely academic FEA sims, some using a laughable 2W power. I'll remain a skeptic.https://nazrulanuar.files.wordpress.com/2008/11/b26_s0060p171-1751.pdf"... Reducing the copper heatsink thickness to form a single gauge leadframe, a thinner version of the dual gauge leadframe, was perceived to present various electrical, thermal and reliability failure mode and mechanisms, specifically die cracking. This study presents an in-depth simulation and analysis to determine whether the thinner heatsink leadframe version is capable of achieving the defined customer product requirements on their electrical, thermal and reliability performances in a DPAK package."" Results revealed that the safest leadframe thickness range is within 0.5 - 1.0mm. The original diepad thickness falls within the safe range. Selecting the 0.5mm as the new diepad thickness for the single gauge leadframe design was as straightforward as referring from the leads thickness of the original dual gauge design. Assembly, ambient electrical, and reliability testing were carried out for the carrier devices (non-auto and automotive types) in DPAK production line. Zero-hour electrical and reliability test results revealed that products satisfied all test specification requirements for both automotive and non-automotive devices."https://ieeexplore.ieee.org/document/7365171If the thickness limit is only about die cracking, no mention of thermals- they might have forgotten higher power dissipation >20W?For TO-220 single gauge, I find the thin tab warps and doesn't contact a heatsink well, becasue of the bolt shoulder/insulator bushing contact area. This is why I hate the sneaky cheap package.I think JEDEC should have issued a new package part number, they did for all the old parts such as TO-3, TO-92 creating more chaos when it was totally unnecessary.