You know, now that you mention it, I have a bunch of DC-DC boards as well, buck converters, LM2596S based, they are not the most efficient but great for prototyping; both voltage and current limited separately adjustable, if anybody needs one. Vin 4.5-40VDC, Vout 3.0-36.5 VDC, Iout max is (optimistically) 3 amps, if this would be useful. -j
On Thu, Nov 19, 2020 at 3:07 PM Nick Edgington via TriEmbed < [email protected]> wrote: > I also have in my box of stuff a number of *ARTESYN NFC40-48T05-15 in > DC/DC 36-72V [email protected]& [email protected] > <https://pdf1.alldatasheet.com/datasheet-pdf/view/156797/ARTESYN/NFC40-48T05-15.html>* > isolated DC-DC converter modules, most forklifts and golf carts seem to > run 48v, they have never been used and are a little overkill here, I had > bought them for a POE project If they would help you are welcome to one. > > Nick > > On Thu, Nov 19, 2020 at 2:37 PM John Wettroth via TriEmbed < > [email protected]> wrote: > >> Pete, >> If the high current peaks are a small fraction of the time, you can >> "bypass" your way around it- I don't know if the ESP gadgets do this- maybe >> you or others do. >> >> There are several systems that do this in either simple or pretty complex >> ways. We called these techniques "BFC" for big fat capacitor. >> >> If you have a high current spike that is drawn for some time at some >> current- the product iT is charge- coulombs. Charge is also CV, so you can >> charge up a cap and dump into your load. The simplest way to do this to >> have big cap at the load fed by a low value resistor to limit recharge >> current to something you can live with. If the duty cycle is low, you >> can blast out a big pulse and then have plenty of time to charge back up >> before its needed. The problem is usually that in this simple case, you >> need to use a much larger cap 10x than just CV would dictate because while >> the cap is discharging- the charge is depleting and its voltage is >> falling (I/c =dv/dt). To limit the droop to something liveable, you uses >> an 8x or 10x sized cap- this way it only droops 10 or 12% over the burst. >> >> The first time that I ever saw this trick was in two way pagers way back >> when. The reciever on a pager drew nothing but when 2 ways came out, every >> now and then, they needed to send a little text message and that drew a >> bunch of current. This was the techniuque. In two way pagers, they >> engineered in the droop and started with transmit power kind of dialed back >> and as the cap discharged, it turned up the relative power in order to keep >> a constant total power output. Pretty clever, this was early days of >> supercaps but they were high impedance, the newer ones would be great- like >> from Maxwell. I think they just used a few thousand uF tantalum or some >> kind of nice electrolytic like a Sanyo OS-Con. >> >> There are quite a few systems that use this trick- I've seen a lot of >> hobby (and pro) spot welders that do this. A lot of energy harvesting >> systems take in energy as the can until they get enough and then do their >> high powered thing and start the cycle again. Walmart had these little >> solar powered LCD price tags (about 2 x 1" cell) that worked this >> way. The host system had IR emitters in the ceiling that sent command to >> the tags. The tags could always receive but they communicated >> acknowldgements back to the system with an IR led when they could. The >> time budget was something like an hour or something- better than sending a >> person with a price gun etc. >> >> I saw a fancier system at Rockwell Automation- AKA Allen Bradely. A >> common problem in industrial is "last gasp" mode on power failures. In >> these little PLC's they need to shutdown in an orderly way and it took >> someting like a minute. Batteries weren't an option in most cases due to >> life. They came up with a clever little discrete circuit using maybe 4 >> transistors and an inductor. It consited of a boost converter that took >> the 24v and made something like 300v to charge a HV cap. The same little >> circuit could turn around and become a buck converter that could take the >> 300v and bring it back to 24v when the power failed. This takes a >> different tack and uses a pretty nice bit of physics. The energy in a >> capacitor is 1/2 CV^2, by boosting up the voltage they could get this >> squared energy. Energy is Power x Time, (watt-seconds or joules). When >> the engineer showed me his solution, I was amazed and we couldn't make >> anything any cheaper or better really. >> >> I guess the ultimate in this is Xenon flash strobes though I don't think >> phones have to rely on this for using LED flash- the battery has such a low >> impedance, you just hammer it for a little bit. >> >> I have a little Ryobi cordless nailer- I don't know exactly how it works >> but the final action is a piston that runs from an air resevoir. I don't >> know if it has a little tiny air compressor that fills up the air resevoir >> or some kind of piston run by solenoid to recharge the air. It >> recycles really quickly. There is a tear down by AVe on the web. I need >> to watch it again. >> >> If you know the peak current, duration, etc- you can see if this works >> for the ESP32. The charge storage IT is good but the energy storage with >> the 1/2CV^2 with a buck boost could work probably. I would think that a >> regulators like Nick found would be simplest- its kind of ideally suited >> excecpt for the 5v max Vin. >> >> >> >> 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:* Thursday, November 19, 2020 10:47 AM >> *To:* [email protected] >> *Subject:* Re: [TriEmbed] Powering ESP32 from an 8v golf cart battery >> >> Thanks for sharing, this, John. The other day trying to gauge how much >> Paul's golf cart battery would be drained with a linear vs switching >> regulator a very quick glance of ESP32 stuff gave a guestimate of about >> 4.7V*50mA (but I guessed this wasted power wasn't relevant to Paul). But I >> hadn't thought at all about peak currents as they relate to regulator >> choice, and more importantly how much time is spent at those higher >> currents. >> >> But I'm writing to wonder how much help decoupling the regulator and >> minimizing inductance might help with transient scenarios like you describe >> below? Or would the cap dumping current just fake out the regulator and >> simply make the droop happen a little later? >> >> -Pete >> On 11/19/20 8:53 AM, John Wettroth via TriEmbed wrote: >> >> That's a nice part Nick. Like a lot of modern parts on small process, >> its kind of designed around one LiIon cell operation. I like the "green >> mode" stuff. LTC and Maxim make some parts like that. The difficulty with >> switchover type parts is when you have a big load transient (eg- a transmit >> burst). If the part is in the low quiescent mode, it can droop and cause >> havoc.I noticed it has a forced green mode pin which could alleviate this >> with some thought in software. A lot of times, its easier to have a >> seperate regulator for the high current case or if they can be split up. >> >> I didn't realize that these ESP devices require so much current, I've >> only played with one on the bench pretty casually. For the 8v input case, >> you really might want to consider a buck converter unless the high current >> only runs very intermittently. The power wasted in a linear could create >> potential heat problems. You're talking about getting rid of 1.5 watts >> from your 8v source. >> >> I agree with Nick on those DFN packages- awful, you're into hot air or >> oven reflow. I like parts that come in a variety of packages including >> through hole, this is getting rare these days. >> >> Regards, >> John M. Wettroth >> (984) 329-5420 (home) >> (919) 349-9875 (cell) >> >> ------------------------------ >> *From:* Nick Edgington [mailto:[email protected] >> <[email protected]>] >> *Sent:* Wednesday, November 18, 2020 6:44 PM >> *To:* Josh Wyatt >> *Cc:* [email protected]; TriEmbed Discussion >> *Subject:* Re: [TriEmbed] Powering ESP32 from an 8v golf cart battery >> >> personal I like the STM *LD39130SJ30R* >> <https://www.st.com/resource/en/datasheet/ld39130s.pdf>which is a good >> match for esp32 it will do 300ma with a 300mv drop the quiescent current is >> a remarkable 1 µA in green mode, 45 µA in normal mode which matched with >> the ULP mode on the esp32, Not a problem with a golf cart but important >> for low power sensor. and to top it of STM will send you a couple for just >> the shipping cost, >> >> The package a somewhat of a pain. >> >> Nick >> >> I have a number of the regulator board I pictured earlier should you be >> near Apex and want one. >> >> >> nje >> >> On Wed, Nov 18, 2020 at 1:17 PM Josh Wyatt via TriEmbed < >> [email protected]> wrote: >> >>> 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_4537398578539011642_m_4427072674128384416_m_133033098193379331_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 >>>> >>>> _______________________________________________ >>> 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 >>> >>> >> _______________________________________________ >> 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 >> <[email protected]?subject=unsubscribe> >> >> _______________________________________________ >> 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 >> >> _______________________________________________ > 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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