This is awesome info John, I'm enjoying the read. >From personal experience, the ESP32S (and ESP8266) can be pretty power hungry when the radios are on, and are particularly sensitive to brownouts... I try to use something with at least 300mA and with good, stiff caps.
Thanks, Josh On Wed, Nov 18, 2020 at 9:42 AM John Wettroth via TriEmbed < [email protected]> wrote: > Shane, > There are a ton and its unfortunately one of these "it depends" kind of > things. But here are a few and why. > > Most of the stuff I do is pretty small, low current stuff and 2.7 or 3.3v- > an 8 bit uP and a display with some RF. Very low quiescent parts > suitable for circuits with sleep mode, etc. A lot of my stuff lives > outside and runs on a 12v battery so I try to shoot for -40C operation and > 16v Max vin. Temp range matters for capacitors mostly and dropout. I buy > almost exclusively from Digikey. Their search engine and service is > amazing even if they cost a bit more. I tend to design very low power > things and like low Iq for sleep operation. Generally very low Iq means > poor HF rejection (you need loop gain)- in RF stuff, I'll compromise on Iq > and shut the block down, etc. I prefer newer parts, there has been so much > progress in the last 15 years, its amazing- there is no reason to use a > 7805 for any real design- even cheap stuff. There are better and even > cheaper alternatives if you're building more than a few hundred. At low > volumes, 7805's can be awfully cheap but they're really only designed as > 60/120 Hz type regulators in a traditional AC supply. > > Some old favorites- > > Micrel (Mchip owns Micrel linear now) MIC5203, 5205 series of BiCMOS > types. PNP pass element but controlled drop out current. 16v 50/150 mA, > Iq 1 mA max. Micrel invented BiCMOS pretty much and its good to see that > Microchip is keeping a lot of their parts. > > Microchip 1791 is a great HV regulator- 30v max in, 70 mA out, load dump > (48V), Iq 70 uA. Microchip makes tons of cheap analog parts these days and > lot of good linears. They acquired Telcom semi many years ago which was a > big CMOS linear company (like Maxim). Newer CMOS stuff is good but the > older stuff is not so good- done on large processes and traded Low Iq for > performance- very slow load and line transient recovery, no PSRR, etc. > > Toko TK11625 and TK1150, Digikey dropped Toko but I still have a lot of > these around- they're officially obsolete but they're plentiful everywhere > and there are newer alternatives. Available in TO-92, 100 mA, Tk71150 is 5v > LDO with good HF rejection for low noise for a post after a switcher, > Quiescent is OK at 300 uA, Seiko makes similar BiCMOS parts, can be hard > to find these days. Microchip basically copied these regulators to create > their line and DigiKey wants to keep Mchip happy. > > TI TLV1117 A "special" very low Iq LM1117 variant, quiescent of 100 uA. > Better PSRR and dropout. Good in 3 Alkaline of 1 LiIon to 2.5v apps. Max > Vin is 5.5v, only downside. > > Some favorites lately (doing low cost stuff) > > Diodes Inc AP-7381 series. Available in TO-92 option still for quick > perfboard builds and breadboard. Cheap. Very low Quiescent, 50/150 > mA variants. Digikey large stocks always. > > ABLIC S-812Cxx series. 1uA Iq, 10-100 mA output depend on voltage. > Quiescent useful for running a real time clock or deep shutdown on a HV > input. > > Anything that Maxim or LTC/ADI makes are invariably awesome but low volume > pricing (<10k) is awful. Real customers pay nothing like those prices > believe me. I have odds and ends of Maxim leftovers but never have what I > need. TI has better pricing but isn't innovating much in this area- the > TLV1117 is an exception- excellent. > > In your Golf Cart app, what's your load current min and max and vin min > and max. Any big line or load steps? Temp range and size could help too. > Any special operation needs like sleep? > > After 25 years in Standard Products at Maxim, I can talk Linear IC's more > than anyone cares to listen. Take care- shoot me a private mail or call if > you have specific questions. > > Regards, > John M. Wettroth > (984) 329-5420 (home) > (919) 349-9875 (cell) > > > ------------------------------ > *From:* Shane Trent [mailto:[email protected]] > *Sent:* Tuesday, November 17, 2020 9:57 AM > *To:* [email protected] > *Cc:* Pete Soper; TriEmbed Discussion > *Subject:* Re: [TriEmbed] Powering ESP32 from an 8v golf cart battery > > John, > > Thank you for your breakdown on voltage regulators. Would you mind sharing > some of your favorite part numbers in the "Modern BiCMOS LDOs"? > > Thanks! > Shane > > On Mon, Nov 16, 2020 at 5:52 PM John Wettroth via TriEmbed < > [email protected]> wrote: > >> I'll put my 2 cents in here for a few subtleties. I defined >> probably 1000 different linear and switching regulators at Maxim in my 25 >> years. >> >> >> Vout plus dropout is pretty good overall. But don't forget that dropout >> is defined where the output voltage drops 100 mV. Its coming out of >> regulation and all the goodness that linears give you stops happening. You >> also want to do this at max load, max output tolerance and worst temp. The >> drop out for bipolars decreases for higher temps which helps but at very >> cold temps, it can grow- a lot a very cold. This is not allways well >> specified. >> >> There are several classes of dropout that are driven by the design of the >> ouput stage >> >> Vdropout >> >> 2v standard bipolar linears like the 7805 use an NPN darlington >> output- nice low impedance and easy to use. >> 1v LM1117 type bipolar linears use a Sziklai modified darlington >> with an NPN follower driven by a PNP- pretty good comprimise >> .5v LM2940 PNP pass element parts have low dropout but some squirelly >> stability issues at times and can have high quiescent at dropout >> .1v PMOS or charge pumped NPN pass element types that looks like a >> small resistance in dropout. Quiescent can be very low. >> . >> Depending on the type of regulator, there are subtlties that happen >> around dropout. >> >> Old bipolar regulators like the 7805 have a drop out of about 2v >> conservatively. The output is an emitter follower darlington stage which >> is 2 vbe's (.7v each) and 2 Vce sat (about .2v each). This is about 1.8v. >> Since the output is a follower, it has a gain of 1 and are generally very >> well behaved with very little thought given to bypassing and stability. >> High frequency rejection is poor and accuracy is somewhat poor. >> >> First generation bipolar LDO's like the LM2940 etc, used a PNP output >> stage with a grounded NPN pulling its base down. These parts have two Vce >> sats in the dropout path (about .5v). These transistors have gain on top >> of the error amp gain and get unstable without following the the bypassing >> instructions closely. The output cap becomes the dominant pole and the ESR >> of the output cap has to in a specific range- neither two small or two >> large. The other annoying feature of this class is as you approach >> dropout- the beta provided by the PNP pass element goes south and they can >> draw lots of current at or near dropout trying to keep the PNP in >> saturation. In low power circuits, this can cause a sort of latching >> action and flatten a battery in no time. >> >> The LM1117 type second gen bipolar LDO's have a NPN follower ouput. >> These have the benefit of a follower but only moderate dropout >> performance. They were basically invented to make 3.3v from 5v which a >> 7805 couldn't do. Good for point of load but kind of mediocre otherwise. >> >> Modern BiCMOS LDO's generally have a PMOS pass element and some MOS and >> Bipolar circuits.. These can have very low quiescent, very low noise and >> the lowest dropout possible. They are also pretty stable with most loads >> but take a signicant cap on the output usually. Something like a 10 uF >> ceramic. Microchip make some good low cost parts in this class. Probably >> my favorites. >> >> There are all CMOS LDO's that share most of features of the last category >> but don't get the low noise and high accurancy generally. >> >> One other issue is your 8v battery. The charging voltage on a Lead Acid >> could be over 10V which is a common abs max for many linears. >> >> My 2 cents. >> >> >> >> >> >> >> >> >> Regards, >> John M. Wettroth >> (984) 329-5420 (home) >> (919) 349-9875 (cell) >> >> >> ------------------------------ >> *From:* TriEmbed [mailto:[email protected]] *On Behalf Of *Pete >> Soper via TriEmbed >> *Sent:* Monday, November 16, 2020 10:46 AM >> *To:* [email protected] >> *Subject:* Re: [TriEmbed] Powering ESP32 from an 8v golf cart battery >> >> >> On 11/15/20 10:34 PM, The MacDougals via TriEmbed wrote: >> >> _______________________________________________ >> Triangle, NC Embedded Computing mailing list >> >> To post message: [email protected] >> List info: >> http://mail.triembed.org/mailman/listinfo/triembed_triembed.org >> TriEmbed web site: http://TriEmbed.org >> To unsubscribe, click link and send a blank message: mailto: >> [email protected]?subject=unsubscribe >> >> > > -- > [image: photo] > *Shane D Trent* > Patent Agent > > 919-348-0061 | [email protected] > > ShaneTrent.com | Skype: skype:shane.trent1 > <#m_189338381597980778_SignatureSanitizer_SafeHtmlFilter_> > Raleigh, North Carolina > [image: Social icon] <http://www.linkedin.com/in/shanetrent> [image: > Social icon] <http://twitter.com/sdtrent> > Create your own email signature > <https://www.wisestamp.com/create-own-signature/?utm_source=promotion&utm_medium=signature&utm_campaign=create_your_own&srcid=> > _______________________________________________ > Triangle, NC Embedded Computing mailing list > > To post message: [email protected] > List info: http://mail.triembed.org/mailman/listinfo/triembed_triembed.org > TriEmbed web site: http://TriEmbed.org > To unsubscribe, click link and send a blank message: mailto: > [email protected]?subject=unsubscribe > >
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