<div dir="ltr">This is awesome info John, I'm enjoying the read.<div><br></div><div>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.</div><div><br></div><div>Thanks,<br>Josh</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Nov 18, 2020 at 9:42 AM John Wettroth via TriEmbed <<a href="mailto:triembed@triembed.org">triembed@triembed.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
<div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">Shane,</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">There are a ton and its unfortunately one of these "it
depends" kind of things. But here are a few and why.</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">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.
</font></span><span><font color="#0000ff" size="2" face="Arial">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.</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">Some old favorites-</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">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.</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">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.</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"><span><font color="#0000ff" size="2" face="Arial">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. </font></span></font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"><span></span></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"><span></span></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">Some favorites lately (doing low cost
stuff)</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">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.</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">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.</font></span></div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div dir="ltr" align="left"><span><font color="#0000ff" size="2" face="Arial">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.</font></span></div>
<div dir="ltr" align="left"><span></span><span></span><span></span><span></span><font color="#0000ff" size="2" face="Arial"></font> </div>
<div><span><font color="#0000ff" size="2" face="Arial">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?</font></span></div>
<div><span><font color="#0000ff" size="2" face="Arial"></font></span> </div>
<div><span><font color="#0000ff" size="2" face="Arial">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.</font></span></div>
<p><font size="2">Regards,<br>John M. Wettroth<br>(984) 329-5420 (home)<br>(919)
349-9875 (cell) </font></p>
<div> </div><br>
<div lang="en-us" dir="ltr" align="left">
<hr>
<font size="2" face="Tahoma"><b>From:</b> Shane Trent [mailto:<a href="mailto:shanedtrent@gmail.com" target="_blank">shanedtrent@gmail.com</a>]
<br><b>Sent:</b> Tuesday, November 17, 2020 9:57 AM<br><b>To:</b>
<a href="mailto:jwet@mindspring.com" target="_blank">jwet@mindspring.com</a><br><b>Cc:</b> Pete Soper; TriEmbed
Discussion<br><b>Subject:</b> Re: [TriEmbed] Powering ESP32 from an 8v golf cart
battery<br></font><br></div>
<div></div>
<div dir="ltr">John,
<div><br></div>
<div>Thank you for your breakdown on voltage regulators. Would you mind sharing
some of your favorite part numbers in the "Modern BiCMOS LDOs"? </div>
<div><br>Thanks!</div>
<div>Shane</div></div><br>
<div class="gmail_quote">
<div class="gmail_attr" dir="ltr">On Mon, Nov 16, 2020 at 5:52 PM John Wettroth via
TriEmbed <<a href="mailto:triembed@triembed.org" target="_blank">triembed@triembed.org</a>>
wrote:<br></div>
<blockquote class="gmail_quote" style="padding-left:1ex;border-left:1px solid rgb(204,204,204);margin:0px 0px 0px 0.8ex"><u></u>
<div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>There are
several classes of dropout that are driven by the design of the ouput
stage</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>Vdropout</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>2v standard bipolar linears
like the 7805 use an NPN darlington output- nice low impedance and easy to
use.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>1v LM1117 type bipolar linears
use a Sziklai modified darlington with an NPN follower driven by a PNP- pretty
good comprimise</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>.5v LM2940 PNP pass element parts
have low dropout but some squirelly stability issues at times and can have
high quiescent at dropout</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>.1v PMOS or charge pumped NPN pass
element types that looks like a small resistance in dropout.
Quiescent can be very low.</span></font></div>
<div dir="ltr" align="left"><span></span><font face="Arial"><font size="2"><font color="#0000ff">.</font></font></font></div>
<div dir="ltr" align="left"><font face="Arial"><font size="2"><font color="#0000ff"><span>Depending on the type of regulator, there are subtlties
that happen around dropout.</span></font></font></font></div>
<div dir="ltr" align="left"><font face="Arial"><font size="2"><font color="#0000ff"><span></span></font></font></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>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.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span>My 2
cents.</span></font></div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div dir="ltr" align="left"><font color="#0000ff" size="2" face="Arial"><span></span></font> </div>
<div> </div>
<p><font size="2">Regards,<br>John M. Wettroth<br>(984) 329-5420 (home)<br>(919)
349-9875 (cell) </font></p>
<div> </div><br>
<div lang="en-us" dir="ltr" align="left">
<hr>
<font size="2" face="Tahoma"><b>From:</b> TriEmbed [mailto:<a href="mailto:triembed-bounces@triembed.org" target="_blank">triembed-bounces@triembed.org</a>] <b>On Behalf Of </b>Pete
Soper via TriEmbed<br><b>Sent:</b> Monday, November 16, 2020 10:46
AM<br><b>To:</b> <a href="mailto:triembed@triembed.org" target="_blank">triembed@triembed.org</a><br><b>Subject:</b> Re: [TriEmbed]
Powering ESP32 from an 8v golf cart battery<br></font><br></div>
<div></div>
<p><br></p>
<div>On 11/15/20 10:34 PM, The MacDougals via TriEmbed wrote:<br></div>
<blockquote type="cite"></blockquote></div>_______________________________________________<br>Triangle,
NC Embedded Computing mailing list<br><br>To post message: <a href="mailto:TriEmbed@triembed.org" target="_blank">TriEmbed@triembed.org</a><br>List info: <a href="http://mail.triembed.org/mailman/listinfo/triembed_triembed.org" rel="noreferrer" target="_blank">http://mail.triembed.org/mailman/listinfo/triembed_triembed.org</a><br>TriEmbed
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