I had not seen that cascoded circuit yet, it's interesting indeed. I just wonder what the total efficiency would be, according to the datasheets it runs at about 80 - 85% in standard configuration, so the cascoded circuit is probably 70-75% as you loose quite a bit of efficiency in the gate charge @ 1MHz and the on resistance is not all that low either (around 260mOhm @ 6V).
I can't change the current design of the concept boards as they are at the PCB manufacturer already. I do expect to reach a higher efficiency than 80% in my design, but we'll see. Michel On Jan 31, 5:52 pm, Nick <n...@desmith.net> wrote: > On Jan 31, 5:57 am, Cobra007 <mic...@xiac.com> wrote: > > > You could convert a battery voltage to a nixie voltage relatively easy > > with a MAX771 circuit. It will only not give you the maximum > > efficiency. What I have done is basically design a circuit (using > > multiple ICs) that together function in a similar way as the MAX771, > > but slightly different in order to increase the efficiency. So it's a > > bit more complicated than just using 1 IC, but I hope it pays off the > > effort. > > The MAX771 is marked "Not recommended for new designs" (its > deprecated) and has been so for several years (maybe 10?). The MAX1771 > is its replacement. The 771/1771 are not good at low input voltages - > its a topology that would need bootstrapping, which then begs the > question: "Why use it in such a specialised design". As size is such a > key issue here, I would probably go for something that switched in the > MHz range so the inductor is far smaller. The TPS61040/61041 are > really nice devices that I've used a few times > -http://www.ti.com/product/tps61040http://www.ti.com/lit/ds/slvs413f/slvs413f.pdf. > > Have a look at this EDN Design Ideas - "Cascode MOSFET increase boost > regulator's input and output voltage ranges" for some ideas... One > basic problem with straight boost converters of this topology is that > they require a high voltage FET and the physics of such FETs means > that they are generally not logic-level driven and mechanically large > - other topologies work far better in this application - have a look > at "flyback converters" - they use low voltage FETs with low Vgs and > which are physically small. > > Nick -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to neonixie-l@googlegroups.com. To unsubscribe from this group, send email to neonixie-l+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
