[TriEmbed] Powering ESP32 from an 8v golf cart battery
Nick Edgington
nickedgington at edgingtonlabs.com
Wed Nov 18 17:43:51 CST 2020
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 <
triembed at triembed.org> 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 <
> triembed at triembed.org> 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:shanedtrent at gmail.com]
>> *Sent:* Tuesday, November 17, 2020 9:57 AM
>> *To:* jwet at mindspring.com
>> *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 <
>> triembed at triembed.org> 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:triembed-bounces at triembed.org] *On Behalf Of *Pete
>>> Soper via TriEmbed
>>> *Sent:* Monday, November 16, 2020 10:46 AM
>>> *To:* triembed at triembed.org
>>> *Subject:* Re: [TriEmbed] Powering ESP32 from an 8v golf cart battery
>>>
>>>
>>> On 11/15/20 10:34 PM, The MacDougals via TriEmbed wrote:
>>>
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>>
>> --
>> [image: photo]
>> *Shane D Trent*
>> Patent Agent
>>
>> 919-348-0061 | shanedtrent at gmail.com
>>
>> ShaneTrent.com | Skype: skype:shane.trent1
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