https://www.digikey.com/product-detail/en/linear-technology-analog-devices/LTM8078IY-PBF/161-LTM8078IY-PBF-ND/10668252 It has a nice combination of input and output range, and the size is insane: about 1/4" square. It will do forced synchronous, burst, or synchronized switching. I wonder if it can be persuaded to convert a positive rail to two negative outputs. Sadly, LT Spice does not yet include a model for this one. My designs often need a few negative supplies, and negative switchers a neglected area. I'd love to xray one of these. I can't imagine how they crammed the inductors inside. -- John Larkin Highland Technology, Inc trk jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
nice little switcher
Started by ●December 25, 2019
Reply by ●December 25, 20192019-12-25
John Larkin wrote...> >https://www.digikey.com/product-detail/en/linear-technology-analog-devices/LTM8078IY-PBF/161-LTM8078IY-PBF-ND/10668252 > > I wonder if it can be persuaded to convert a > positive rail to two negative outputs.I'll say, of course, connect the GND pin to your desired most negative output voltage, and Vout of that buck converter to ground. -- Thanks, - Win
Reply by ●December 25, 20192019-12-25
On 25 Dec 2019 06:52:24 -0800, Winfield Hill <winfieldhill@yahoo.com> wrote:>John Larkin wrote... >> >>https://www.digikey.com/product-detail/en/linear-technology-analog-devices/LTM8078IY-PBF/161-LTM8078IY-PBF-ND/10668252 >> >> I wonder if it can be persuaded to convert a >> positive rail to two negative outputs. > > I'll say, of course, connect the GND pin to your > desired most negative output voltage, and Vout > of that buck converter to ground.That works for one of the negative outputs. Make, say, -8 volts first from +24, which is what I need now. But I also need -1.5. The second regulator section has +24 as its V+ input, and -8 as its ground. If its feedback pin is a resistor to ground, it thinks it's a +6.5 volt reg riding on -8, with a +32 supply. I think that will work, but the tolerance stackup is awful for the -1.5. I'm powering some THS4303 opamps at their abs max supply voltage, +4.5 and -1.5. The -8 is for something else. I could make, say, -8 and -2.5, and LDO the -2.5 down to -1.5, which takes one more chip but is reasonably efficient. Or use an opamp to create the feedback to the second switcher. Do the math to make the second switcher really regulate to -1.5. Hard to think about at 7AM and 6400 feet. I might Spice it with two LTM8023's. -- John Larkin Highland Technology, Inc trk jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●December 25, 20192019-12-25
Why don’t you select another switcher? It is expensive, has bad efficiency, hard to solder and what not Could roll your own for a tenth of the price with a lot better performance Cheers Klaus
Reply by ●December 25, 20192019-12-25
Klaus Kragelund wrote...> > Why don't you select another switcher? > > It is expensive, has bad efficiency, > hard to solder and what not. > > Could roll your own for a tenth of the > price with a lot better performance.Yes, small is not always beautiful. -- Thanks, - Win
Reply by ●December 26, 20192019-12-26
On 25 Dec 2019 13:12:19 -0800, Winfield Hill <winfieldhill@yahoo.com> wrote:>Klaus Kragelund wrote... >> >> Why don't you select another switcher? >> >> It is expensive, has bad efficiency, >> hard to solder and what not. >> >> Could roll your own for a tenth of the >> price with a lot better performance. > > Yes, small is not always beautiful.We want complex designs to work first pass. Design spins and added time to market are expensive. Noisy switchers make jitter in fast circuits. The LTM bricks are small and quiet. I don't want to compromise a $4000 box by saving a few dollars. -- John Larkin Highland Technology, Inc trk jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
Reply by ●December 26, 20192019-12-26
First hit on Digikey: https://www.digikey.com/product-detail/en/microchip-technology/MIC28513-2YFL-T5/576-4885-1-ND/5216764 Add an inductor and cap and your set For you 10 dollar switcher we do a complete motor control including RFI filter, PCB, power supplies, oh and also the motor and all pump hydraulics and mechatronics But yes, we spend some time on it Cheers Klaus
Reply by ●December 26, 20192019-12-26
Reply by ●December 26, 20192019-12-26
4000 USD is your sales price, right? With 5x mark up you are at 80 Production CTP is probably 10 So a 10 USD switcher would be 14% of your Vom Cheers Klaus
Reply by ●December 26, 20192019-12-26
