OK, I tracked down where the turnon surge current goes. It's the Vcc current of the two LT1011 comparators. Spice is a useful tool as long as you don't always believe what it reports.
Just after startup, the current in L1 is zero. Stays low until the first time the fet turns on.
I suppose you can find a definition of "efficiency" that comes up with that value. It's around 90% for most of the charging curve, and around
90% in the zones in which it will actually operate.
What equation (or clickey box) did you use to measure efficiency?
Surprise! Fets in a switching regulator have high peak currents! The customer won't see that, because I'll have bypass caps on my board.
The 9 volts will actually be present for a while before the boost inverter is enabled. It's only turned on when they want to use the laser. This will work.
The VCC current of the two LT1011 devices is a single spike at t=0, and nada thereafter. You're grasping at straws. Vladimir's assessment is correct.
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Only when it suits your purposes ?:-)
I ran it clear out to where equilibrium was reached. Averaged the 9V current over 500us out there at the end.... 110mW input... load is
60mW... what's the efficiency?
If you really need support only a very light load, there's much better ways to do it.
Do feel free to post all your "cute" circuits as LTspice files... makes for great fun >:-} ...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.
You're flailing. I like to see you flail :-) You didn't even look at the waveforms I posted. You're just scrambling to cover your own ass. ...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.
That's after the cap is charged up. We're idling, waiting for the next laser pulse. There's very little battery drain in this state. What matters is the 3 kilowatts of pulsed laser power, and the net load on the battery in operation. The efficiency that matters is when we're recharging the caps after a laser pulse, and it will be high.
When the laser is not in use, the customer will tell me to shut down, go to low power mode.
I threw the R5-R11 values in there for loop simulation, and because I
*want* to discharge the caps and see the top-off behavior of this switcher. Which is excellent.
You can't understand my application, but that's not the point. This is a new, at least to me, switcher topology, and it will work fine, and you and Vlad just don't like it.
There is, in theory, no load once the caps are charged up, until the next shot. I will scale up R5-R11 in the real thing, to a few megs maybe, as that's the only thing discharging the caps between shots... well, that and D1 leakage. What matters is the efficiency during recharge after a shot, with the caps ramping from roughly 38 volts back to idle at 48. At 1 milliwatt into R11, I don't much care if the efficiency is 50%.
--
| 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.
Engineering? I think not. What you love is trying to be vain and mean. You're not very good at any of the above.
The surge current that you complain about is the same thing Vlad complained about: the 2 uF cap, C1, has to be charged. That's trivial, given that I'm going to expect the customer to charge maybe 25 or 50 uF of input bypass capacitor.
What are the specifications, load, etc.? Let me know and I'll whip up a simpler way. ...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.
ISTM that a better metric to determine how happy I would be with it, if it were mine, would be watt-seconds in the output capacitor divided by watt-seconds supplied by the source, calculated over the charging interval.
For curosity, I did that and I see that it puts 4.6 w*s into the output capacitor while using 5 w*s from the source. That would be about 92% efficient. Not bad.
I'll convert this to modern technology in LTspice and post it. ...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.
Simply not true. I often use LTspice to play with a circuit to see what it might do. I also despise topologies (circuits without any values or described purpose) which you post a lot. Then again i do not design ICs which pretty well better work mighty close to right the first time. The IP $ in a mask set is not trivial.
--
| 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'd take a close look at the oscillator. It doesn't seem possible it could run due to the pullup resistor R1 going to +5. You would think the logic would lock up as soon as HB1 output switched to a low logic level.
Also, the 5V swing on C1 looks like it would drive the input of HB1 above
+5V and below ground.
Driving 5 HC14's in parallel into a 2N2369 to ground looks like it would cause some hurt somewhere.
LTspice is supposed to be able to run PSpice netlists. There is no schematic so I don't know how you select which waveforms to view. JK
The inductor current ramps up until the drop across R2 hits 0.2, and then the rest of the stuff pulls the HB1 input low, so it does oscillate. But it is messy. The low side of C2 could have been grounded, but I'd just as soon do it the way I did it.
Yup, it will bang the ESD diodes.
Driving the mosfet gate is fine. But the the c-b junction of the 2369 gets involved. Even messier.
There is no netlist.
Something like this might work for a really cheap booster:
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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
--
| 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.
That connection provides hysteresis. Actually didn't need the 'HC14's, could have used 'HC04's instead. I've used that scheme a lot on custom chips to provide a symmetrical digital delay... mostly to avoid crowbar problems with H-bridges.
I've addressed that in multiple posts involving using inverter packages as oscillators... all it does is affect the time constant.
There is a PSpice schematic
I can provide that. Actually you would need both the .CIR file and the .NET, concatenate as .CIR, works just fine
PSpice Schematics is a much more user friendly GUI so, when clients request running under LTspice, I just run the .CIR. (In LTspice, File, Open...)
Still need to address the initial surge which you said would bring down the system. Maybe a switched-in soft-start resistor? ...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.
--
| 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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