It was not "advertised" as doing anything but what it does.
It's cheap, cute, and efficient. It uses a small number of standard parts. Its startup and topoff behavior are excellent. Your technical criticisms are simply wrong; neither the peak drain voltage nor the peak drain current are problems, much less "infinite." You just don't like it.
You totally missed (or evaded) the point. Is anyone surprised? ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
Hey!!!! It's CUTE! Did you miss that ?>:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
This is a 3W converter? place the 9V node symbol on the other side of R8 to include control power in your loss equation.
Then, note the free gate drive energy - about 50mW resistive loss, half of it in R3, the other half in IC 'A'......and that's not counting IC A's internal switching losses (it's a schmitt???).
Your coupling and filter capacitors are ESR-free. While there are some pretty low-esr parts out there, the issue is never going away.
With small converters, measurement error, even in a simulation, is significant. Luckily, efficiency usually isn't.
The losses in the ESR of the capacitor you're charging are not included in the efficiency equation, either. If a 1mR sensor makes that much difference under peak/average loading, imagine what 8mR esr will do?
Capacitive dumping, without energy storage is a 50/50 proposition.
Most of the integrated boost controllers need a lot of discretes, which take room. And they often do stuff that I don't want, like burst mode, foldback, complex and poorly defined stuff.
Besides, I'm a circuit designer. It's not much fun to just copy reference designs.
I simulated one LTC circuit that did weird things so I asked for support. Useless. And there's no way to figure it out from the data sheet and an encrypted bahavioral model.
Your critiques are purely emotional. It works. Neither of the flaws you cited are problems. Find something actually wrong with it.
I think I should back out of this thread. I do not understand your definition of efficiency because you have no load on your simulation. I always thought that efficiency was Pout/Pin. Since Pout is close to zero (steady state) your efficiency cannot be very good.
Maybe R7 (1 m Ohm) can be removed to reduce a node since the FET already has 25 m Ohms ?
You could also maybe place the 1 m Ohm ESR of L3, L5 (and L4 -- R1, C7 -- R9 if you want to) inside the part itself to reduce nodes and possibly help it to run a bit faster but maybe you want them there so you can think about the circuit better.
All energy transfer in this circuit is capacitor to capacitor, or voltage to voltage. The only intermediate energy storage is leakage inductance, and that's never there where it's needed.
Every time you do that, you throw half the energy away.
You can change the model yourself and see this. Just remember that for capacitor charging storage, the 'output' voltage has I x esr subtracted from it, at all times.
The same considerations are needed for the source, where efficiency calculations are concerned.
On Thu, 04 Jul 2013 18:39:21 -0700, John Larkin wrote:
Reducing the current sensor values to be less than 1/10th the dominant impedances is the usual way of compensating for their effect in the circuit.
Here's a skeptic afflicted with esr. Losses in both the source and the load are considered in the total efficiency, just to agravate things. It's not necessary - ignoring input and output esr, but measuring the real peak currents flowing in the sensors, easily sends efficiency below 50%;
120) SYMATTR InstName B1 SYMBOL res 1216 656 R90 WINDOW 0 70 60 VBottom 2 WINDOW 3 78 61 VTop 2 SYMATTR InstName R1 SYMATTR Value 1K SYMBOL cap 1248 736 R0 WINDOW 0 -37 63 Left 2 WINDOW 3 -43 94 Left 2 SYMATTR InstName C2 SYMATTR Value 10n SYMBOL Digital\\schmtinv 160 512 R0 SYMATTR InstName A1 SYMATTR Value2 Vhigh=5 Vt=2.5 Vh=0.5 SYMATTR SpiceLine Td=5n SYMBOL cap 80 928 R0 WINDOW 0 44 60 Left 2 WINDOW 3 37 92 Left 2 SYMATTR InstName C4 SYMATTR Value 500p SYMBOL res 128 464 R270 WINDOW 0 88 58 VTop 2 WINDOW 3 74 57 VBottom 2 SYMATTR InstName R4 SYMATTR Value 2K SYMBOL Digital\\schmtinv 304 448 R0 SYMATTR InstName A2 SYMATTR Value2 Vhigh=5 Vt=2.5 Vh=1 SYMATTR SpiceLine Td=5n SYMBOL Digital\\schmtinv 304 384 R0 SYMATTR InstName A3 SYMATTR Value2 Vhigh=5 Vt=2.5 Vh=1 SYMATTR SpiceLine Td=5n SYMBOL Digital\\schmtinv 304 512 R0 SYMATTR InstName A4 SYMATTR Value2 Vhigh=5 Vt=2.5 Vh=1 SYMATTR SpiceLine Td=5n SYMBOL Digital\\schmtinv 304 320 R0 SYMATTR InstName A5 SYMATTR Value2 Vhigh=5 Vt=2.5 Vh=1 SYMATTR SpiceLine Td=5n SYMBOL cap 1424 352 R0 WINDOW 0 -70 43 Left 2 WINDOW 3 -64 77 Left 2 SYMATTR InstName C5 SYMATTR Value 4µ SYMBOL res 640 320 R0 WINDOW 0 47 70 Left 2 WINDOW 3 41 102 Left 2 SYMATTR InstName R7 SYMATTR Value 1m SYMBOL res 640 672 R0 WINDOW 0 70 52 Left 2 WINDOW 3 75 86 Left 2 SYMATTR InstName R10 SYMATTR Value 0.2 SYMBOL Comparators\\LT1011 368 704 M0 SYMATTR InstName U1 SYMBOL voltage -96 160 R0 WINDOW 0 63 53 Left 2 WINDOW 3 61 85 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V1 SYMATTR Value 0.2 SYMBOL Comparators\\LT1011 368 912 M0 SYMATTR InstName U2 SYMBOL voltage -96 464 R0 WINDOW 0 61 45 Left 2 WINDOW 3 54 83 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName V3 SYMATTR Value 1.25 SYMBOL res 640 912 R0 WINDOW 0 -56 37 Left 2 WINDOW 3 -57 71 Left 2 SYMATTR InstName R5 SYMATTR Value 1K SYMBOL res 832 880 R90 WINDOW 0 69 56 VBottom 2 WINDOW 3 74 56 VTop 2 SYMATTR InstName R11 SYMATTR Value 37.4K SYMBOL cap 800 288 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C1 SYMATTR Value 2µ SYMATTR SpiceLine Rser=.008 SYMBOL res 640 608 R90 WINDOW 0 65 54 VBottom 2 WINDOW 3 71 54 VTop 2 SYMATTR InstName R2 SYMATTR Value 1K SYMBOL cap 496 720 R0 WINDOW 0 54 32 Left 2 WINDOW 3 43 63 Left 2 SYMATTR InstName C8 SYMATTR Value 300p SYMBOL schottky 880 416 R180 WINDOW 0 42 2 Left 2 WINDOW 3 -44 -85 Left 2 SYMATTR InstName D2 SYMATTR Value 10MQ060N SYMATTR Description Diode SYMATTR Type diode SYMBOL res 1424 208 R0 SYMATTR InstName R12 SYMATTR Value 8m SYMBOL res 224 128 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R13 SYMATTR Value .01 TEXT 1184 576 Left 2 !.tran 0 4m 20u 10n uic TEXT 1168 480 Left 2 ;SKEPTIC CONVERTER TEXT 1208 528 Left 2 ;JL July 3 2013 TEXT 688 128 Left 2 !K L1 L2 0.99 TEXT 192 624 Left 2 ;74HC14 TEXT 160 504 Left 2 ;OSC TEXT 736 176 Left 2 ;1:1 TEXT 160 808 Left 2 ;USE LM393
It's not necessary - ignoring input and output esr, but measuring the real peak currents flowing in the sensors, easily sends efficiency below 50%; The fact that it's better than 50% in the early stages is the effect if the leakage terms in the choke - but these are not employed effectively at the conversion frequency.
If you look at the postive terminal of V3, you'll see that it's not '9'.
I did already. Wimp. Wimp. Whine, Whine. ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
I really have you in a tizzy. I've succeeded >:-} ...Jim Thompson
--
| James E.Thompson | mens |
| Analog Innovations | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| San Tan Valley, AZ 85142 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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