While playing around with 2s RC lipos (8.4V, up to 40-80A discharge power!!!) I burnt out a maple mini (not the BAITE version) very quickly (maybe only the voltage regulator, I’ll check this later). Even with the BAITE ones (they have the “bigger” AMS1117 clone voltage regulator) I wouldn’t connect them directly to such powerful lipos: I burnt those AMS clones on other devices – they are really bad made and after they are dead, they tend to give the whole input voltage to the output.
This happend without any particular load on the mini!
As a silly and cheap workaround I use a separate LM7805 (with heatsink) to reduce the power and connected it to the “Vin” of the maple.
While playing around with 2s RC lipos (8.4V, up to 40-80A discharge power!!!) I burnt out a maple mini (not the BAITE version) very quickly (maybe only the voltage regulator, I’ll check this later). Even with the BAITE ones (they have the “bigger” AMS1117 clone voltage regulator) I wouldn’t connect them directly to such powerful lipos: I burnt those AMS clones on other devices – they are really bad made and after they are dead, they tend to give the whole input voltage to the output.
This happend without any particular load on the mini!
As a silly and cheap workaround I use a separate LM7805 (with heatsink) to reduce the power and connected it to the “Vin” of the maple.
U = 8.4V I=50mA
P = 8.4*0.05 = 0.42W
T = 25 + 0.42W*90C/W = 25 + 37.8 = 62.8C
63degC cannot damage the 1117 voltage regulator, I guess..
failure at the first on-to-off is normally found out at the second the off-to-on.
5v into a LM7805 does not give out 5v, almost certainly below V-usb, what then happens is higher level wins!
stephen
absolutely no idea how the brain cell did that.
IEC/EN General Safety. Report: SPCLVD 1407030-1. IEC/EN-60950-1, 2nd Edition. MTBF (25°C). MIL-HDBK-217F. 4185 x 10³ hours. (70°C). MIL-HDBT-217F
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U = 8.4V I=50mA
P = 8.4*0.05 = 0.42W
T = 25 + 0.42W*90C/W = 25 + 37.8 = 62.8C
63degC cannot damage the 1117 voltage regulator, I guess..
once upon a time i modified my motorbike with a solid block full bridge rectifier, it handled the 6v to 12v inverter for the 55W halogen full beam headlight. took about 8 secs to ramp up the extra load, not good at 60mph at night.
now i’m thinking i’m puzzled as to why i needed a bridge rectifier ?
i’d also changed it from a single carb to a twin carb head, so said rectifier got stuck in an empty space with a rag to stop the rattle.
70 miles down the motorway, in the outside lane at 70mph, i always had the headlight on, i had a 12″ square smoke tail right under the petrol tank.
i’ve never known how i got to the emergency lane, with the luggage, seat with its two rounded over hex head bolts, wiring harness and petrol tank all off in about 30-50 seconds. needed a new pair of gloves.
now i tend to overly heat sink things.
i’ve only ever done this once.
take one 6v electrolytic cap, fed it full wave rectified 6v ac, eyes got it, blind 5 flights of stairs yelling gangway from my newly rented room to the nearest water in the kitchen.
stephen
i’ve only ever done this once.
take one 6v electrolytic cap, fed it full wave rectified 6v ac, eyes got it, blind 5 flights of stairs yelling gangway from my newly rented room to the nearest water in the kitchen.
stephen
But this sounds really unlikely, unless very thick wire was used to connect to the regulator.
Perhaps the regulator is a cloned product and has reduced operating limits?
Perhaps the regulator is a cloned product and has reduced operating limits?
Beware of fakes. I have a bag full of AMS1117-5 (SOT223) here that fail in unpleasant ways (pass input direct to output) when you exceed about 10v input, at any current draw. As long as you don’t exceed about 10v input they are ok,
Beware of fakes. I have a bag full of AMS1117-5 (SOT223) here that fail in unpleasant ways (pass input direct to output) when you exceed about 10v input, at any current draw. As long as you don’t exceed about 10v input they are ok,
OK, folks … the above is just a complete distortion of fact. I’m going to defend Aliexpress since it is my primary off-shore store and I have no experience with DX; but Alliexpress is a wrapper service and not the seller. I seriously doubt there is much oversight from mother Ali, but I do know that I have had one order canceled by Aliexpress when the vendor appeared to oversell their inventory. Aliexpress put a 10-day hold on all orders and required the vendor to “prove” supply capability. No charges were ever placed on my credit card.
IMO:
If you buy from off-shore Asian sources, you need to do your own quality testing. QA for items that seemingly are near free when free shipping is considered are almost assuredly not fully tested – if tested at all.
So, if you buy a PSU or even those ugly prototype power units – test them! Honestly, PGM (piss-gripe-moan) will only go so far toward making you feel better… the best defense is a great offense. TEST FIRST.
Ray
The AMS1117 series of adjustable and fixed regulators are easy to
use and are protected against short circuit and thermal overloads.
Thermal protection circuitry will shut-down the regulator should
the junction temperature exceed 165°C at the sense point.
Unless the regulator is a fake, or a defect unit, the only way you can destroy it with a “fizz”, is a) wrong polarity of the Vin, b) pins mismatch, c) high input voltage Vin, d) maybe a high inductive load (generating highvoltage peaks).
A high capacitive load (ie 1F blocking capacitor at Vout) should not have destroyed the regulator as the overcurrent protection does not allow that.
A high temperature of the package, ie. 140°C will decrease its life, however..
it has a reason why I put this thread under “maple mini”:
As we all know there are two different kinds of the maple mini clone out there:
The BAITE one (with the large AMS(?)1117))
the “other one” (with a two small (smd transitor like) voltage regulators) – It seems it’s not really available at the moment.
The “other one” was destroyed while connecting it directly to a 2s lipo (40C).
So I (and other ones here) researched a little bit and found out, that many chinese clone voltage (especially AMS1117) regulators may make big problems with higher voltage / ampere.
So the big question is, if also the BAITE ones are involved by this problem so we should add a warning to the Wiki.
<…>
So the big question is, if also the BAITE ones are involved by this problem so we should add a warning to the Wiki.
I never reviewed any item but sometimes you can understand something about the quality.
DX has also a UK, USA and AU shops with much less items, never bought from there.
I agree with ray but I am not a professional, I buy items for fun. Very few devices are working on italian volcanoes doing simple tasks like moving a mirror for an instrument (an FTIR spectrometer).
The typical thermal resistance of SOT-223 package soldered on PCB is about 80-90 C/W.
The power limit is calculated:
Tmax = Tambient + W * 90
Tmax = 125 by datasheet, and Tambient=40, then:
Wmax =(125-40)/90 = 0.95W
It is very easy to calculate the maximum current of device given the input voltage. Some examples:
Vin=8.5V, Vout=3.3 => Imax = 0.95 / (8.5-3.3) = 182 mA, much lower than rated current of device.
Vin=8.5V, Vout=5 => Imax = 0.95 / (8.5-5) = 270 mA
Vin=12V, Vout=5 => Imax = 0.95 / (12-7) = 190 mA
Vin=12V, Vout=3.3 => Imax = 0.95 /(12-3.3) = 109 mA
Normally, AMS1117 has internally thermal protection that switches off the output if the temperature is beyond limits, but you can not depend on this, specially with questionable quality parts.
All cheap breadboard power supplies use AMS1117 in SOT-223 package. The power limit of this device is very low, try to feed it with an external regulator with as low voltage as possible, to reduce the heating dissipation ( Vin must be greater than Vout+1 )
