"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
Yeahbut you tried to cram a burst mode at one of my questions and I hadn't even asked for a design.
It wasn't because burst mode was best for my app, it was because you didn't know PWM - not exactly honest was it.
Input?
RL
Like you, right?
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
Snicker...
I also came across a voltage vs. current move paper by TI (maybe unitrode) not sure. That may have something in it too.
It should be some where in those links above.
Cheers
Display driver.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
Oh joy -- so, do you have the frequency headroom to use a lower inductance coil with the same core, to get the saturation current up?
-- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
Has the value of inductor been selected properly? The rule of thumb for a boost converter in continuous conduction mode is L = (V * D)/(R*I_l*f), where the parameters are evaluated at the _lowest_ specified (worst case for a boost) input voltage. V is the input voltage, I_l is the DC inductor current (I_o/(1-D)), D is the duty cycle, f is the switching frequency. R is the "ripple current ratio" and has an optimum value of 0.4 for continuous conduction mode in most cases.
At low voltages the inductor can be sized solely based on the DC load current requirements - if the current limiting is fast enough it doesn't matter if the inductor saturates under abnormal conditions.
If the inductor is still too big maybe use discontinuous mode instead? It'll be harder to stabilize, unfortunately.
Car ignition key?
Of course ;-) ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 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 where my thoughts are progressing... ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 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.
Just how big does this inductor have to be? Looking here:
A 100 uH 150 mA inductor looks like it could be a chip inductor a few mm high.
A stupid look on their face as they ignore you? ;-)
-- You can't have a sense of humor, if you have no sense.
Zits?
-- "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)
nnnnkkkkkk-splutter.. :D
k
est
and
ake it
But 4 ohms d.c.r. means it'll drop 600mV @ 150mA. Increasing f by a factor of 3 reduces i^2*r loss by that same factor. Or, keep the loss and trade for a smaller L and C.
Switching inductors without magnetic shields make RFI, magnetic nasties, etc. Shielded are better.
-- Cheers, James Arthur
-- Your "questions" are little more than trolls designed to attract and focus attention on you and, since you asked for "help" and it was offered and you rejected it, out of hand, you're an ingrate with an agenda disparate from ours, which is to help.
Do try to pay attention sometimes!
All I asked for was load curves for bicycle dynamos.
I didn't ask anyone to design it for me - I already have that well in hand.
I didn't reject the few (unsolicited) solutions from the minority of smart-asses pretending to know more than they did - I just ignored them.
-- Well, since ignorance seems to be your strong suit, that was probably a good move on your part.
Well I certainly saved myself some aggro by ignoring the unsuitable topology suggested by your chum.
Can't help wondering whether he'd have got it right if he had known how to do the correct way.
Ian _and_ a notable other poster on this topic are severely ignorant about the real world.
PWM BUCK is trivial. I chose BURST for the hub dynamo because it would be a freebie around the 555, and I was intent on rubbing the 555 up some snobbish noses ;-)
PWM BOOST is NOT trivial, though I'm well on my way to an off-the-wall STABLE solution... found by running the math instead of my mouth. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 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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