You have a huge inductor in the motor, which will put huge transient spikes everywhere, and that includes the places you don't want them. I am not sure you can overdo the isolation. Al the rules apply single-point grounding, Pi networks of L's and C's are a good start. An isolated DC-DC converter would not be overkill. I am sure you mention it but what is the bus voltage out of the battery.
Nick On Thu, Nov 19, 2020 at 10:46 AM Pete Soper via TriEmbed < [email protected]> wrote: > 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_-2812097307455768919_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 > >
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