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]]
*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] <mailto:[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] <mailto:[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]
<mailto:[email protected]>]
*Sent:* Tuesday, November 17, 2020 9:57 AM
*To:* [email protected] <mailto:[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] <mailto:[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]
<mailto:[email protected]>] *On Behalf Of
*Pete Soper via TriEmbed
*Sent:* Monday, November 16, 2020 10:46 AM
*To:* [email protected] <mailto:[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:
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