Feeler Extremely efficient boost circuits

[BluRay]

Yeah, whats going on here? are these still getting made? if so i would like in on say 3-4. and they are adjustable right?


Another question, when will these be ready to sell and shipped out?





Tommy

 

[rkcstr]

Where can you go to get PCB's assembled cheaply?

I don't know how much they charge, but the place I had some PCBs made offers assembly too. They had good prices on the PCBs, so they may have good prices on the assembly too? Advanced Circuits, www.4pcb.com. You have the option of them sourcing parts or you sending the parts in (they're in the US) and obviously then can make the PCBs too. If you don't mind, I would appreciate a referral too if you do go with them (PM me in that case).

 

[mmykle]

Bump...

Does anyone know whats going on with these? I'm tempted to PM Toked but he's probably still busy with school work (Speaking of which I should really be working on my hw now... :). Phoenix, you said you were thinking about making some, do you think you would have time to put that together? If not and no one else is up to it I could just use the company Rkcstr was talking about, but I'd have to wait till winter break before I had time to do it.

Or... I do have access to a pcb at my internship. Is there a parts list somewhere that I missed? Maybe I can make a few myself.

 

[treb76]

Yeah, whats going on here? are these still getting made? if so i would like in on say 3-4. and they are adjustable right?
Another question, when will these be ready to sell and shipped out?
Tommy

not according to toked.

 

[treb76]

shameless bump

 

[jamilm9]

never used it
http://www.batchpcb.com/

 

[Zom-B]

usually you make a board with multiple drivers in an array. Then order v-groove or milling (if they support it) to separate them.

 

[treb76]

I misread it ;D

 

[rkcstr]

If you get 0.031" board, you can easily cut it with some sharp scissors.   Doesn't look like BatchPCB supports thinner board, though.  That place is pretty cheap if you just want a small amount of boards, but if you plan to make a decent number of them, its cheaper to go elsewhere.

It looks like (based on the specs listed in that layout), the exact dimensional area would cost about $0.37 per board, but that doesn't allow for adequate spacing around each board for separation.  And, I don't know if they require it, but there may also be necessary spacing around the edge of the board, which would add to total cost.

To compare prices:  Looking at their prices ($2.50/sq in) a maximum (10x15", 150sq in) board filled with as many PCBs as possible would cost $375 (before shipping), comparatively, I got 4 boards of similar size (160 sq in) for about the same price for ALL 4.

 

[phoenix3200]

Trust me, this project is far from dead...I've been doing a lot of research into making (something quite similar to) this.  I found a site which charges $0.45 a square inch after setup costs - but I still don't think my design is ready for manufacture yet.

Since I'm planning on using a different chip than the TPS61200 (who really needs a 0.3 V minimum operating voltage?), I'm not completely confident that my board will work with a AA/AAA...at least at the current levels people would like to see.  That, and I'd like to try out some reflow soldering on other components before building this.

As for the fixed/adjustable, I'd prefer to just make them in set ranges since the pots would cost me as much as the chip will.

My only (empty) promise is that this is being looked at. If you want a timetable, I'd guess early December would be the soonest you'll see this.

 

[mmykle]

Well I can run that circuit diagram by the people I work with and see if that's possible to build and if they have the parts. I don't know if the branch I'm working in would carry those pieces.

Phoenix, what chip would you use besides the .3V chip? That chip is rated for a 95% duty cycle according to Texas Instruments. If you could find one with a 100% duty cycle that would be really cool. Also, to my understanding "boost" chips just boost a low DC to a higher AC. Is that right?

 

[phoenix3200]

Phoenix, what chip would you use besides the .3V chip? That chip is rated for a 95% duty cycle according to Texas Instruments. If you could find one with a 100% duty cycle that would be really cool. Also, to my understanding "boost" chips just boost a low DC to a higher AC. Is that right?

I can't remember the particular model, but it's another TI chip that operates at 0.9 V. I'm a little worried that the load expected of the battery (up to 1 W) would drop even a brand new AA to less than the planned operating voltage, but even if that happens, I could distribute lower mA versions, or people could use multiple batteries in series/parallel.

As for what "boost" means - The chip sets its output based on a feedback voltage, and to do that, it alters its duty cycle. Due to the duty cycle, the output will fluctuate, but then again, that's why we use capacitors.

 

[treb76]

I can't remember the particular model, but it's another TI chip that operates at 0.9 V.

TPS61020

How do you calculate the wattage?

 

[phoenix3200]

TPS61020

How do you calculate the wattage?

That's the one. TI changed the *** pinout in that circuit and put the enable pin on the opposite corner of the chip from the battery pin. Bastards. I still was able to cut the area down to 10x5mm for a double sided board, but the final board design will probably be more square than that (but less than 8mm wide) and take up a hair more space

Power ("Wattage")=Current * Voltage. At roughly 5.5 V output and 200mA output, that's roughly 1.1 W output. Disregarding efficiency, a 1.5V battery would need to supply 700mA to the circuit. If you include efficiency losses, you're probably asking for around 900 mA from the battery.

The question isn't if the chip can handle the current, the question is if the battery can handle the load.

 

[Zom-B]

[quote author=treb76 link=1222224046/60#76 date=1226352515]TPS61020

How do you calculate the wattage?

That's the one. TI changed the *** pinout in that circuit and put the enable pin on the opposite corner of the chip from the battery pin. Bastards. I still was able to cut the area down to 10x5mm for a double sided board, but the final board design will probably be more square than that (but less than 8mm wide) and take up a hair more space

Power ("Wattage")=Current * Voltage. At roughly 5.5 V output and 200mA output, that's roughly 1.1 W output. Disregarding efficiency, a 1.5V battery would need to supply 700mA to the circuit. If you include efficiency losses, you're probably asking for around 900 mA from the battery.

The question isn't if the chip can handle the current, the question is if the battery can handle the load.[/quote]

When a battery drains, the voltage drops. The driver still tries to keep the power the same, so the current rises.

If the battery is 1.0V, the current is already >1.1A. If the battery drops to 0.6V, the current is >1.8A (if the battery can handle it, that is)

The battery drains at an ever increasing rate. This'll be very VERY bad for rechargeable batteries, which are not deep-discharge types. (except protected Li-Ion)

 

[phoenix3200]

When a battery drains, the voltage drops. The driver still tries to keep the power the same, so the current rises.

If the battery is 1.0V, the current is already >1.1A. If the battery drops to 0.6V, the current is >1.8A (if the battery can handle it, that is)

The battery drains at an ever increasing rate. This'll be very VERY bad for rechargeable batteries, which are not deep-discharge types. (except protected Li-Ion)

No disagreement there...except I hadn't even considered battery damage or rechargeable batteries yet.  My worry is that the extremely high load of 1.1-1.3 W will drop the load voltage to less than the 0.9 V if the battery has a high internal resistance (e.g. a 1.2 V battery must have an internal resistance less than 0.2 ohms to work)

Imax = Pload/Vload_min = 1.3 W/0.9 = 1.444 A
Rint_max = (Vbat_min - Vload_min)/Imax = (Vbat_min - 0.9)/1.444