On 23/07/13 09.04, Glenn wrote:> On 23/07/13 02.53, Harry Dellamano wrote: > .... >> Expensive fancy pants switcher, 0.24 USD/1K >> >> http://www.digikey.com/product-detail/en/UC3842BD1G/UC3842BD1GOS-ND/921708 >> >> >> Harry > > This series replaced UC384x "long" ago: > > ucc3802 til 100% 0,5mA > http://focus.ti.com/docs/prod/folders/print/ucc3802.html... Quote: "... Features 100�A Typical Starting Supply Current 500�A Typical Operating Supply Current Operation to 1 MHz Internal Soft Start Internal Fault Soft Start Internal Leading-Edge Blanking of the Current Sense Signal 1 Amp Totem-Pole Output 70ns Typical Response from Current-Sense to Gate Drive Output 1.5% Tolerance Voltage Reference Same Pinout as UC3842 and UC3842A ..." You can not ask for more? Glenn
New Improved +/-45V PSU
Started by ●July 18, 2013
Reply by ●July 23, 20132013-07-23
Reply by ●July 23, 20132013-07-23
Glenn <glenn2233@gmail.com> writes:> On 23/07/13 09.04, Glenn wrote: >> On 23/07/13 02.53, Harry Dellamano wrote: >> .... >>> Expensive fancy pants switcher, 0.24 USD/1K >>> >>> http://www.digikey.com/product-detail/en/UC3842BD1G/UC3842BD1GOS-ND/921708 >>> >>> >>> Harry >> >> This series replaced UC384x "long" ago: >> >> ucc3802 til 100% 0,5mA >> http://focus.ti.com/docs/prod/folders/print/ucc3802.html > ... > Quote: "... > Features > 100µA Typical Starting Supply Current > 500µA Typical Operating Supply Current > Operation to 1 MHz > Internal Soft Start > Internal Fault Soft Start > Internal Leading-Edge Blanking of the Current Sense Signal > 1 Amp Totem-Pole Output > 70ns Typical Response from Current-Sense to Gate Drive Output > 1.5% Tolerance Voltage Reference > Same Pinout as UC3842 and UC3842A > ..." > > You can not ask for more?Ah... how about "not being 5x the price?" :) -- John Devereux
Reply by ●July 23, 20132013-07-23
On Tue, 23 Jul 2013 13:03:55 +0100, John Devereux <john@devereux.me.uk> wrote:>Glenn <glenn2233@gmail.com> writes: > >> On 23/07/13 09.04, Glenn wrote: >>> On 23/07/13 02.53, Harry Dellamano wrote: >>> .... >>>> Expensive fancy pants switcher, 0.24 USD/1K >>>> >>>> http://www.digikey.com/product-detail/en/UC3842BD1G/UC3842BD1GOS-ND/921708 >>>> >>>> >>>> Harry >>> >>> This series replaced UC384x "long" ago: >>> >>> ucc3802 til 100% 0,5mA >>> http://focus.ti.com/docs/prod/folders/print/ucc3802.html >> ... >> Quote: "... >> Features >> 100�A Typical Starting Supply Current >> 500�A Typical Operating Supply Current >> Operation to 1 MHz >> Internal Soft Start >> Internal Fault Soft Start >> Internal Leading-Edge Blanking of the Current Sense Signal >> 1 Amp Totem-Pole Output >> 70ns Typical Response from Current-Sense to Gate Drive Output >> 1.5% Tolerance Voltage Reference >> Same Pinout as UC3842 and UC3842A >> ..." >> >> You can not ask for more? > >Ah... how about "not being 5x the price?" :)Some of those features, like the leading-edge blanking and soft start, eliminate external parts. The tradeoff depends on your purchasing and placement costs. If purchasing/placement costs 25 cents per part, it doesn't take many extra parts to sway the balance. I don't mind the cost of some of these switcher parts as much as the complexity and the number of discretes they often need. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●July 23, 20132013-07-23
On 07/23/2013 03:04 AM, Glenn wrote:> On 23/07/13 02.53, Harry Dellamano wrote: > .... >> Expensive fancy pants switcher, 0.24 USD/1K >> >> http://www.digikey.com/product-detail/en/UC3842BD1G/UC3842BD1GOS-ND/921708 >> >> >> Harry > > This series replaced UC384x "long" ago: > > ucc3802 til 100% 0,5mA > http://focus.ti.com/docs/prod/folders/print/ucc3802.html > 2,1 eu > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11464-5-ND > > ->ucc3803 til 100% 0,5mA 2,1 eu > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11466-5-ND > > ->ucc3800 til 100% 0,5mA 2,1 eu > http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11457-5-ND > > > Also these - but they are also outdated: > ( > UCC38C43 > MIC38HC43 > MIC38HC43-1 > MIC38C44 > SG3843 > KA3843 > ISL8843 > TL3843 > ISL8843 > ) > > /GlennThey're about five times the price--what's better about them that's enough to outweigh that? 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 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●July 23, 20132013-07-23
On Tue, 23 Jul 2013 12:05:01 -0400, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 07/23/2013 03:04 AM, Glenn wrote: >> On 23/07/13 02.53, Harry Dellamano wrote: >> .... >>> Expensive fancy pants switcher, 0.24 USD/1K >>> >>> http://www.digikey.com/product-detail/en/UC3842BD1G/UC3842BD1GOS-ND/921708 >>> >>> >>> Harry >> >> This series replaced UC384x "long" ago: >> >> ucc3802 til 100% 0,5mA >> http://focus.ti.com/docs/prod/folders/print/ucc3802.html >> 2,1 eu >> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11464-5-ND >> >> ->ucc3803 til 100% 0,5mA 2,1 eu >> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11466-5-ND >> >> ->ucc3800 til 100% 0,5mA 2,1 eu >> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11457-5-ND >> >> >> Also these - but they are also outdated: >> ( >> UCC38C43 >> MIC38HC43 >> MIC38HC43-1 >> MIC38C44 >> SG3843 >> KA3843 >> ISL8843 >> TL3843 >> ISL8843 >> ) >> >> /Glenn > >They're about five times the price--what's better about them that's >enough to outweigh that? > >Cheers > >Phil HobbsIf you're building a multi-kilobuck instrument in low volume, with high purchasing and placement cost, the book price of a small part doesn't much matter. What really matters is design time and risk. EMI is a big part of that risk. -- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
Reply by ●July 23, 20132013-07-23
On 07/23/2013 12:25 PM, John Larkin wrote:> On Tue, 23 Jul 2013 12:05:01 -0400, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 07/23/2013 03:04 AM, Glenn wrote: >>> On 23/07/13 02.53, Harry Dellamano wrote: >>> .... >>>> Expensive fancy pants switcher, 0.24 USD/1K >>>> >>>> http://www.digikey.com/product-detail/en/UC3842BD1G/UC3842BD1GOS-ND/921708 >>>> >>>> >>>> Harry >>> >>> This series replaced UC384x "long" ago: >>> >>> ucc3802 til 100% 0,5mA >>> http://focus.ti.com/docs/prod/folders/print/ucc3802.html >>> 2,1 eu >>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11464-5-ND >>> >>> ->ucc3803 til 100% 0,5mA 2,1 eu >>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11466-5-ND >>> >>> ->ucc3800 til 100% 0,5mA 2,1 eu >>> http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail?name=296-11457-5-ND >>> >>> >>> Also these - but they are also outdated: >>> ( >>> UCC38C43 >>> MIC38HC43 >>> MIC38HC43-1 >>> MIC38C44 >>> SG3843 >>> KA3843 >>> ISL8843 >>> TL3843 >>> ISL8843 >>> ) >>> >>> /Glenn >> >> They're about five times the price--what's better about them that's >> enough to outweigh that? >> >> Cheers >> >> Phil Hobbs > > > If you're building a multi-kilobuck instrument in low volume, with high > purchasing and placement cost, the book price of a small part doesn't much > matter. What really matters is design time and risk. EMI is a big part of that > risk. > >All true. However, when you're trying to figure out where the bodies are buried, inquiring minds want to know. ;) Cheers Phil -- 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 hobbs at electrooptical dot net http://electrooptical.net
Reply by ●July 23, 20132013-07-23
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message >>>>>> >> If you're building a multi-kilobuck instrument in low volume, with high >> purchasing and placement cost, the book price of a small part doesn't >> much >> matter. What really matters is design time and risk. EMI is a big part of >> that >> risk. >> >> > All true. However, when you're trying to figure out where the bodies are > buried, inquiring minds want to know. ;) > > Cheers > > Phil >You folks are correct, it is not the cost of the parts but design time, risk, heat and EMI just to name a few. I believe that you are taking a risk in your design without protection features that are normally needed. Such as under voltage shutdown and poor short circuit protection. If the 16V supply come up low or if the output is shorted you have a good chance of letting the smoke out. In normal operation your design has a large charge dumping spike at R1 at turn on. This screams for a 1nF cap at Q1-B to ground to mitigate the spike but will greatly effect short circuit protection. Needs lots of tweaking. I used the LT1242 only because it was the only model available in LTSpice. You are correct about LT controllers. They have too many hooks and features, to allow easy integration. Designers using LT parts normally copy the published designs to the letter and not think on their own. LT never learned that a great IC controller has less than 10 pins. If I were task with this design I would probably look at the LM3475 Hysteretic controller from TI. Your design works because this is a simple requirement but most PSU are not this simple and you need to be conformable with IC controllers. Highest regards, Harry
Reply by ●July 23, 20132013-07-23
On Tue, 23 Jul 2013 12:49:12 -0700, "Harry Dellamano" <harryd@tdsystems.org> wrote:> >"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message >>>> >>> >>> If you're building a multi-kilobuck instrument in low volume, with high >>> purchasing and placement cost, the book price of a small part doesn't >>> much >>> matter. What really matters is design time and risk. EMI is a big part of >>> that >>> risk. >>> >>> >> All true. However, when you're trying to figure out where the bodies are >> buried, inquiring minds want to know. ;) >> >> Cheers >> >> Phil >> > You folks are correct, it is not the cost of the parts but design time, >risk, heat and EMI just to name a few. I believe that you are taking a risk >in your design without protection features that are normally needed. Such as >under voltage shutdown and poor short circuit protection. If the 16V supply >come up low or if the output is shorted you have a good chance of letting >the smoke out. In normal operation your design has a large charge dumping >spike at R1 at turn on. This screams for a 1nF cap at Q1-B to ground to >mitigate the spike but will greatly effect short circuit protection. Needs >lots of tweaking.The thing I posted was just a concept, a starting point for playing with. Like I said, I had to run to Safeway. I did a production board of something similar, a schmitt ac-coupled boost converter. It uses a comparator for the source current sensing and it does have an RC in that path. The breadboard works fine and I haven't blown up a single IC so far. The first PCB will be here on Friday. This circuit doesn't mind a shorted load, because the mosfet peak current thing always works. Here's a schmitt-based voltage flipper. It's actually used on a couple of products. https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/DC_DC2.jpg> I used the LT1242 only because it was the only model available in LTSpice.There *is* a schmitt trigger model too! -- 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
Reply by ●July 23, 20132013-07-23
"John Larkin" <jlarkin@highlandtechnology.com> wrote in message news:miqtu8logu045op9fds57o7v8o2a26gh6l@4ax.com...> On Tue, 23 Jul 2013 12:49:12 -0700, "Harry Dellamano" > <harryd@tdsystems.org> wrote: > >> >> You folks are correct, it is not the cost of the parts but design time, >>risk, heat and EMI just to name a few. I believe that you are taking a >>risk >>in your design without protection features that are normally needed. Such >>as >>under voltage shutdown and poor short circuit protection. If the 16V >>supply >>come up low or if the output is shorted you have a good chance of letting >>the smoke out. In normal operation your design has a large charge dumping >>spike at R1 at turn on. This screams for a 1nF cap at Q1-B to ground to >>mitigate the spike but will greatly effect short circuit protection. >>Needs >>lots of tweaking. > > The thing I posted was just a concept, a starting point for playing > with. Like I said, I had to run to Safeway. > > I did a production board of something similar, a schmitt ac-coupled > boost converter. It uses a comparator for the source current sensing > and it does have an RC in that path. The breadboard works fine and I > haven't blown up a single IC so far. The first PCB will be here on > Friday. > > This circuit doesn't mind a shorted load, because the mosfet peak > current thing always works. > > Here's a schmitt-based voltage flipper. It's actually used on a couple > of products. > > https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/DC_DC2.jpg > > >> I used the LT1242 only because it was the only model available in >> LTSpice. > > There *is* a schmitt trigger model too! > > > -- > > John Larkin Highland Technology, Inc >Your sketch is a good case on point. If you replace the LM5112 with a LTC3801 (6 pins) with your feedback scheme, you now have a solid PSU and not a kludge. I have used that topology often, with an "off the shelf" coupled shielded inductor, to get tracking +/-V outputs. Safeway?? Have you ever eaten at "Brown Sugar" in Oakland. We should meet there some time an have grits an eggs. Cheers, Harry
Reply by ●July 23, 20132013-07-23
On Tue, 23 Jul 2013 14:24:47 -0700, "Harry Dellamano" <harryd@tdsystems.org> wrote:> >"John Larkin" <jlarkin@highlandtechnology.com> wrote in message >news:miqtu8logu045op9fds57o7v8o2a26gh6l@4ax.com... >> On Tue, 23 Jul 2013 12:49:12 -0700, "Harry Dellamano" >> <harryd@tdsystems.org> wrote: >> >>> >>> You folks are correct, it is not the cost of the parts but design time, >>>risk, heat and EMI just to name a few. I believe that you are taking a >>>risk >>>in your design without protection features that are normally needed. Such >>>as >>>under voltage shutdown and poor short circuit protection. If the 16V >>>supply >>>come up low or if the output is shorted you have a good chance of letting >>>the smoke out. In normal operation your design has a large charge dumping >>>spike at R1 at turn on. This screams for a 1nF cap at Q1-B to ground to >>>mitigate the spike but will greatly effect short circuit protection. >>>Needs >>>lots of tweaking. >> >> The thing I posted was just a concept, a starting point for playing >> with. Like I said, I had to run to Safeway. >> >> I did a production board of something similar, a schmitt ac-coupled >> boost converter. It uses a comparator for the source current sensing >> and it does have an RC in that path. The breadboard works fine and I >> haven't blown up a single IC so far. The first PCB will be here on >> Friday. >> >> This circuit doesn't mind a shorted load, because the mosfet peak >> current thing always works. >> >> Here's a schmitt-based voltage flipper. It's actually used on a couple >> of products. >> >> https://dl.dropboxusercontent.com/u/53724080/Circuits/Power/DC_DC2.jpg >> >> >>> I used the LT1242 only because it was the only model available in >>> LTSpice. >> >> There *is* a schmitt trigger model too! >> >> >> -- >> >> John Larkin Highland Technology, Inc >> > > Your sketch is a good case on point. If you replace the LM5112 with a >LTC3801 (6 pins) with your feedback scheme, you now have a solid PSU and >not a kludge.Why would you call a perfectly fine, works-as-designed, cute-as-a-button production circuit a kluge? Because it doesn't cost $3 and isn't blessed by some reference design? Besides, the LTC3801 isn't good to 12 volts. Would it even work as an inverter? I have used that topology often, with an "off the shelf">coupled shielded inductor, to get tracking +/-V outputs. > Safeway?? Have you ever eaten at "Brown Sugar" in Oakland. We should meet >there some time an have grits an eggs.The food in San Francisco is fabulous, except for two glaring exceptions: no decent Cajun/Creole, and no good BBQ. Oakland has both. Sure, any time. I love grits. Or come to SF and I'll give you the plant tour and take you to Zuni. They have grits, except that they call it polenta and charge 4 times as much. Zuni is where I discovered cranberry beans. https://dl.dropboxusercontent.com/u/53724080/Food/Cranberry1.jpg -- 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
