I'm just asking what smart people would use for a simple low drop out regulator (3.3v out) low quiescent current a bonus but I am more interested in devices with fewer pins (like 3 if possible). I want a regulated 3.3v for a uP that will mostly be asleep (but the peripherals will gobble power when energized hence what is wasted by the reg is pretty much unimportant). It has to be able to run from 4v or as close to it as possible.
TIA
Some rough specs would help. The LM1117 is the most common LDO, but it has horrible quiescent current consumption (worse than a 78xx series).
The LP2951 has reasonably low Iq and is popular, but it's a bit fussy about the output cap characteristics.
(with most all LDOs and many negative regulators, read the section on output caps with great interest, then read it again and don't go near the limits).
You could try Diodes' AP7313 which looks to me like some Asian ones.
s y
there should be tons to choose from from from all of the usuals it is right in the sweet spot for battery stuff, liion battery is 3.6-4.2V
-Lasse
On a sunny day (Fri, 5 Oct 2012 05:32:40 -0700 (PDT)) it happened " snipped-for-privacy@fonz.dk" wrote in :
If the 4V is stabilised, just use a si diode drop, that makes 3.3V.
1117 is an "MDO", a little better than an LM317 but not much. It wouldn't make 3.3 from 4. It also won't make 2.5 from 3.3... trust me on that.
LP2985IM5-3.3 is nice: sot23, and works with very low ESR caps, namely a big ceramic. 150 mA max.
Here's my fix for trying to get 2.5 from 3.3 with an LM1117:
That's a melf zener used in the forward direction. Worked great.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
How much current do you need ?
50 ma, 100 ma, 150 ma ??TC1014/TC1015/TC1185
"very low dropout voltage, typically 85 mV (TC1014), 180 mV (TC1015), and 270 mV (TC1185) at full-load."
MCP1702 is my favourite- 1uA quiescent.....
Actually that is a bad idea. The voltage drop depends largely on the current. A few years ago I fitted 3.3V memory modules in 5V slots. It turned out I needed to put 2 diodes in series to get somewhere between
3V and 4V (which was perfectly in range for the memory chips).-- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
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yep, probably be fine if you use tens of milliamps all the time, but when the mcu goes to sleep and uses tens of microamps instead you might get i trouble
-Lasse
On a sunny day (Fri, 05 Oct 2012 16:42:34 GMT) it happened snipped-for-privacy@puntnl.niks (Nico Coesel) wrote in :
Yes, it depends, as he gives no current values or tolerance the answer is correct.
Yup, and the data sheet says that too. Even at zero current it typically needs about a volt, and, extrapolating from the curve, maybe
1.1V typical at zero current and -40°C. "MDO" indeed.
One trick I sometimes do is stack 1117's, to get 1.25, then 2.5, with no resistors. For FPGA supplies.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
Stabilized? 4 to 6.2 volts so not very stable.
Many thanks all - I'm looking through he part numbers you all gave. Thanks again!
100 ma covers it. If I keep using the chip then 50ma might be tight.
100 ma covers it. If I keep using the chip then 50ma might be tight.
100 ma covers it. If I keep using the chip then 50ma might be tight.
LP2950! Looks like great stuff, but I've got to re-read the data on bypassing (thanks for that hint too).
On Fri, 05 Oct 2012 21:31:04 +1000, "David Eather" wrote:
--- A little late, too expensive, and way more than 3 pins, but just for grins:
Version 4 SHEET 1 880 680 WIRE -240 -16 -384 -16 WIRE 16 -16 -240 -16 WIRE 224 -16 16 -16 WIRE -240 16 -240 -16 WIRE 224 96 224 -16 WIRE 16 112 16 -16 WIRE -240 128 -240 96 WIRE -16 128 -240 128 WIRE 64 144 48 144 WIRE 160 144 144 144 WIRE -16 160 -64 160 WIRE -64 256 -64 160 WIRE 64 256 -64 256 WIRE 224 256 224 192 WIRE 224 256 144 256 WIRE -384 272 -384 -16 WIRE -240 272 -240 128 WIRE 224 288 224 256 WIRE -64 304 -64 256 WIRE -384 416 -384 352 WIRE -240 416 -240 336 WIRE -240 416 -384 416 WIRE -64 416 -64 384 WIRE -64 416 -240 416 WIRE 16 416 16 176 WIRE 16 416 -64 416 WIRE 224 416 224 368 WIRE 224 416 16 416 WIRE -384 464 -384 416 FLAG -384 464 0 SYMBOL res 208 272 R0 SYMATTR InstName R1 SYMATTR Value 33 SYMATTR SpiceLine "" SYMBOL voltage -384 256 R0 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 WINDOW 3 24 96 Invisible 2 SYMATTR Value2 "" SYMATTR SpiceLine "" SYMATTR Value PULSE(4 6 .001 .01) SYMATTR InstName V1 SYMBOL pnp 160 192 M180 SYMATTR InstName Q1 SYMATTR Value 2N3906 SYMBOL res 48 240 M90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 10k SYMATTR SpiceLine "" SYMBOL res -80 288 R0 WINDOW 0 -39 32 Left 2 WINDOW 3 -72 62 Left 2 SYMATTR InstName R3 SYMATTR Value 31250 SYMATTR SpiceLine "" SYMBOL Opamps\\LTC1050 16 80 R0 WINDOW 0 -104 -6 Left 2 WINDOW 3 -136 25 Left 2 SYMATTR InstName U1 SYMBOL References\\LT1634-2.5 -240 304 R0 WINDOW 3 12 -45 Left 2 WINDOW 0 15 -76 Left 2 SYMATTR InstName U2 SYMBOL res -256 0 R0 SYMATTR InstName R4 SYMATTR Value 15K SYMATTR SpiceLine "" SYMBOL res 160 128 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R5 SYMATTR Value 100 SYMATTR SpiceLine "" TEXT -376 440 Left 2 !.tran .02
-- JF
You're right, that's hilarious! Try adding a little load capacitance.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
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