1v boost converter

[Dr_Doggy]

Recently i purchased some TL499acp
https://www.ti.com/lit/ds/symlink/tl499a.pdf
and most of the components listed on the datasheet, i am trying to boost a single AA battery, to run a micro-controller(16f526) and a RGB LED, so circuit is good, testing with pickit, circuit shuts down and led stops blinking below 3v (5v may be too much as i didnt load down my LEDS 2.4-3.6videal

so. i will start from the begining:
according the datasheet i was to get a 50uH inductor, so i did test circuit with this one:
https://www.digikey.ca/product-detail/en/B78108S1473J/495-5568-1-ND/4245861

which obviously failed for obvious reasons, so i got some of these aswell:
https://www.digikey.ca/product-search/en?KeyWords=811-2046-ND &WT.z_header=search_go

that surprised me, i thought those would work forsure, but no, so next i tried this one:
https://www.digikey.ca/product-search/en/inductors-coils-chokes/fixed-inductors/196627?k=M8385-ND

and still nothing, so as always in these situations i did what i always do, started pulling resistors, first with pin4 resistor, then pin2 and pulled it to ground.

what i noticed is then is that i was actually using a 1.2v battery, so i switched it up to a 1.5v battery, and i $hit you not that the volts pulled up to stable 4v, powered down and up ideally several tests, and ran blinky program for 48hrs, again no resistors, on huge coil, at that point the battery died, and when i switched it out converter did not come back online. Its been said that im under volting it, so maybe i had a freak battery, either way i need resolution, should i really switch to oscillator circuit, i usually dont have much success,, I am experienced with multi-vibrator, and thinking about using that to drive boost switches.. here is block diag of what i'm dealing with:

2.5v SOLAR CELL ---DIODE --- AA BATTERY ---- app

2.5v SOLAR CELL ---DIODE --- AA BATTERY --boost conv-- 3.5v MICRO

need suggestion, cannot modify/stack solar cell, what is "Best" (easiest -- cost effective), adjustments i need to make here?

 

[ronsimpson]

Your second inductor should work!
Please send a schematic of your LT499 circuit.
The data sheet does not show a input capacitor that should be there.
Going from a single battery to 5V you can't get more than 40mA out.

 

[Dr_Doggy]

i have done the math, but to reconfirm things i did hardware test, and 3v is ideal, consuming a max of 40mA when hardware is at full tilt, which will be rare in the field, running one led at a time we are looking closer to 15ma,

i dont like that full tilt consumption due to such a draw on the battery , but booster may need to support it,

I am using that exact circuit, and did include that capacitor on the battery, 330uf, and diode/capacitor 200uf on output pin 8. also i pulled pin 2,4 straight to ground when it worked for that day..

i have hooked circuit back up, 200ohm on pin4 , with no load, and ref still to ground, i am convinced though im under volted since when i put power to pin3 i get good spike ,, but then drops to 900mV, this is on a fresh battery at 1.6v, no load

i am actually able even keep the micro controller going if i rub the battery wire along the inductor leg and cause alot of noise there

 

[Mosaic]

Any reason why a LI ion AAA or AA style rechargeable can't work?

I use them for PIC circuits just fine...they will last quite a while if the PIC sleeps. Like 40- 50 Days.

 

[Dr_Doggy]

ohya, are rechargeable, but solar cell is only 2.5v

 

[Mosaic]

yes...charge pump the solar output using an MPPT V&I range to charge the battery.
Part like this:ADP5090
Key Features : 1 – Optimizes efficient conversion of harvested limited power down to 10µW – 1mW range with best in class sub-µW operation losses 2 – Programmable maximum power point tracking with open circuit voltage sensing ensures most energy extracted from harvester 3 – 250nA quiescent current in deep-sleep mode prolongs operation time with minimized loss of ambient energy 4 – Integrated charge pump circuitry enables cold start at 380-mV input voltage with no energy on system node.

https://www.analog.com/static/imported-files/data_sheets/ADP5090.pdf

 

[Dr_Doggy]

ok ty, but i already stocked these 494 IC's. but one thing, i could not find your part at manufacture, but found equivalent, but like all other through hole parts, min vin=1.5v, but i will consider those for next time,

it is good to know though that i got right inductor! and with that knowledge i continued to pull wires(debugging),

circuit is now under 300Ohm test load;
pulling wire on pin 7 seems to be a straw.... i have gotten output to stableize at 10v, >200ma draw at battery, but cannot lower volts!
here is pic of current schematic,
putting anything on pin 7 seems to destabilize,
output adjustments are still not responding when i do put pot back on pin2..
and look at photo 2 as well, this dip on output is totally random and goes away while im typing here.
ima keep tryin thing, but rite now ref pin does not lower volts

 

[Dr_Doggy]

*update!
d2 in my diag seems to be the factor!
after trying different configs, pulling that diode, original circuit diag is now working! referring to the original schematic i had it between the last two nodes on the output(the cap and pot), so i am surprised it had an effect.

Rcl = 3k3
Re2 =3k3
Re1 = 3k3
Cp = 0.1uf
pin7 now tied to ground

circuit is now stable and drawing only milli amps, with the blinky program(single leds)

But I am still having problem on power up, when i plug input vcc pin from battery cap to booster, plugging it straight in will only raise volts to 1.5v ish, what i need to do is pull and plug the Vcc pin about 3x in accurately timed pulses, causing the output to raise each time, but I cannot leave Vcc in until output is at 3v, until that and otherwise circuit wont stable-ise?

so close i can taste it!

 

[Dr_Doggy]

done! turns out that the panel could run the pic but the blocking diode put it under. boost converter IC failed due to under voltage after battery reduced to 75% charge, plus the original batteries are only 1.2v, instead of a joule thief though i used a discrete multi-vibrator to drive my boost inductor, then a capacitor multiplier circuit to boost up to charging voltage, and installed 3 series batteries for pic.

thnx again!