Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: <snip>> 48V warts aren't at all common IME. Modems used to use 24VAC ones, but > there aren't many of those left.+48VDC is a telecommunications industry standard voltage. There's tons of adapters all over the place. But the wart's often distal from the electric power outlet as shown below: https://sep.yimg.com/ay/yhst-46542159655918/ruckus-wireless-48vdc-68a-power-adapter-w-6ft-ac-cord-20.jpg Thank you, -- Don Kuenz, KB7RPU
On 2017-12-15, Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:> I've only seen modems use 9V AC, to get something like +/-12V I assume > > I wonder how much hardware it takes to use USB-C, that's 20V,5A > laptops are starting use it for chargingYou'd need a micro with in-built USB. the increased voltage, and re-purposed data lines need to be negotiated over a data channel. -- This email has not been checked by half-arsed antivirus software
On Friday, December 15, 2017 at 8:07:24 AM UTC-8, Phil Hobbs wrote:> 48V warts aren't at all common IME. Modems used to use 24VAC ones, but > there aren't many of those left.POE :== Power On Ethernet Thanks to POE (Power On Ethernet) expect to see more 48V used. It was always a telco standard, so there's good DC/DC converter support. A combination of 24VAC for the isolation transformer, and a voltage-doubler rectifier (two Schottky diodes, two capacitors), makes circa 65VDC and that's in the acceptable input range for those telco-style DC/DC converters.
"Phil Hobbs" <pcdhSpamMeSenseless@electrooptical.net> wrote in message news:prmdnY0Ed4Gvbq7HnZ2dnUU7-YudnZ2d@supernews.com...> 48V warts aren't at all common IME. Modems used to use 24VAC ones, but > there aren't many of those left.Probably uncommon because < 42V is SELV. As for 36, who knows; overshadowed by 24, just not an important value? Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Contract Design Website: https://www.seventransistorlabs.com/
Den fredag den 15. december 2017 kl. 17.07.24 UTC+1 skrev Phil Hobbs:> On 12/15/2017 10:53 AM, George Herold wrote: > > On Thursday, December 14, 2017 at 8:53:36 PM UTC-5, John Larkin wrote: > >> On Thu, 14 Dec 2017 19:59:23 -0500, Phil Hobbs > >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> > >>> On 12/14/2017 07:19 PM, John Larkin wrote: > >>>> On Thu, 14 Dec 2017 17:02:41 -0500, Phil Hobbs > >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>> > >>>>> On 12/14/2017 04:42 PM, John Larkin wrote: > >>>>>> On Thu, 14 Dec 2017 14:40:49 -0500, Phil Hobbs > >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>>>> > >>>>>>> On 12/14/2017 12:17 PM, John Larkin wrote: > >>>>>>>> On Thu, 14 Dec 2017 09:45:17 -0500, Phil Hobbs > >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>>>>>> > >>>>>>>>> Modern buck regulators seem to have way too many features that I can't > >>>>>>>>> turn off or customize. > >>>>>>>>> > >>>>>>>>> The otherwise very nice AOZ1282-1 snookered me by having a 600-us fixed > >>>>>>>>> short-circuit protection interval--it wouldn't start up into a 220 uF > >>>>>>>>> capacitor, even with a very light load. Fortunately, switching to 22 uF > >>>>>>>>> fixed it, and I had some with the right footprint. > >>>>>>>>> > >>>>>>>>> And then many go into stutter mode at light loads, e.g. the MCP16311. > >>>>>>>>> Its brother, the MCP16312, is claimed to stay in vanilla PWM mode > >>>>>>>>> throughout the load range, but the data sheet lies. That bit me once > >>>>>>>>> when I was trying to make an isolated +24 -> +-5V converter for an > >>>>>>>>> industrial control system, using two coupled inductors. Simulated > >>>>>>>>> great, but the undocumented stutter mode of the MCP16312 screwed it up. > >>>>>>>>> > >>>>>>>>> Chips these days. > >>>>>>>>> > >>>>>>>> > >>>>>>>> My latest fave is the TPS54302. It's a 6-pin SOT23, nice and dumb, and > >>>>>>>> behaves very well. > >>>>>>>> > >>>>>>>> There is no usable model (Web-bench never works for me) so I had to > >>>>>>>> breadboard the various compensations, but that's done now. > >>>>>>>> > >>>>>>>> > >>>>>>> Looks like a nice part, but distributor stock appears to be very thin. > >>>>>>> > >>>>>>> Cheers > >>>>>>> > >>>>>>> Phil Hobbs > >>>>>> > >>>>>> I'd better check on that. It's very similar to the AOZ part but, of > >>>>>> course, different pinout. > >>>>>> > >>>>>> > >>>>> Yeah, there's a big run on quite a few chips at the moment, it seems. > >>>>> The AOZ1282-1 is in "full production" but nobody has any more till at > >>>>> least January. It's the 400 mA, 1-MHz version of the vanilla 1282, > >>>>> which is a 1A, 500 kHz part. Faster is nice when you're coming off a > >>>>> 24V rail. > >>> > >>>> > >>>> We just nabbed 500 of the TI parts from Arrow. > >>> > >>> Which was about 40% of the total world supply at that point. Weird--you > >>> don't look at all like Bunker Hunt. ;) > >> > >> Maybe they will be the next bitcoin. > >> > >> > >>>> > >>>> The 54302 works fine making 24 into 5 or 3.3. It gets inefficient > >>>> making +1 (FPGA core voltage) from 24. For that, I went from 24 to 5, > >>>> then 5 to 1. > >>>> > >>>> The TI claims to run up to 3 amps, and it does, but it gets pretty > >>>> warm. 2.5 seems more prudent. Not bad for a SOT-23. > >>>> > >>>> It's not entirely clear how the heat gets out of this chip, so we hung > >>>> some copper on everything. > >>>> > >>>> https://www.dropbox.com/s/mxjunh0ykivkjys/P5_Regs_1.JPG?raw=1 > >>> > >>> Yup, vias are free, pours are cheap, but field fails are _expensive_. > >>> > >>> BTW we took your advice and standardized on the highest > >>> commonly-available wall wart voltage (+24). We use a pretty strict UVLO > >>> setting (19V) so that if somebody connects the wrong supply, nothing > >>> happens. > >> > >> Yeah, somebody might accidentally plug a 12v wart into a 6v box, but > >> it's unlikely anyone will have anything above 24, so no transzorbs > >> needed. Maybe reverse protection, though. > > I went looking for wall warts and found that 48V seemed to be the next > > 'standard' value. I built a gizmo with one. > > (Power plug gets pitted by arcs when it is disconnected 'hot'.) > > > > George H. > > 48V warts aren't at all common IME. Modems used to use 24VAC ones, but > there aren't many of those left.I've only seen modems use 9V AC, to get something like +/-12V I assume I wonder how much hardware it takes to use USB-C, that's 20V,5A laptops are starting use it for charging
On Friday, December 15, 2017 at 11:07:24 AM UTC-5, Phil Hobbs wrote:> On 12/15/2017 10:53 AM, George Herold wrote: > > On Thursday, December 14, 2017 at 8:53:36 PM UTC-5, John Larkin wrote: > >> On Thu, 14 Dec 2017 19:59:23 -0500, Phil Hobbs > >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> > >>> On 12/14/2017 07:19 PM, John Larkin wrote: > >>>> On Thu, 14 Dec 2017 17:02:41 -0500, Phil Hobbs > >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>> > >>>>> On 12/14/2017 04:42 PM, John Larkin wrote: > >>>>>> On Thu, 14 Dec 2017 14:40:49 -0500, Phil Hobbs > >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>>>> > >>>>>>> On 12/14/2017 12:17 PM, John Larkin wrote: > >>>>>>>> On Thu, 14 Dec 2017 09:45:17 -0500, Phil Hobbs > >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>>>>>> > >>>>>>>>> Modern buck regulators seem to have way too many features that I can't > >>>>>>>>> turn off or customize. > >>>>>>>>> > >>>>>>>>> The otherwise very nice AOZ1282-1 snookered me by having a 600-us fixed > >>>>>>>>> short-circuit protection interval--it wouldn't start up into a 220 uF > >>>>>>>>> capacitor, even with a very light load. Fortunately, switching to 22 uF > >>>>>>>>> fixed it, and I had some with the right footprint. > >>>>>>>>> > >>>>>>>>> And then many go into stutter mode at light loads, e.g. the MCP16311. > >>>>>>>>> Its brother, the MCP16312, is claimed to stay in vanilla PWM mode > >>>>>>>>> throughout the load range, but the data sheet lies. That bit me once > >>>>>>>>> when I was trying to make an isolated +24 -> +-5V converter for an > >>>>>>>>> industrial control system, using two coupled inductors. Simulated > >>>>>>>>> great, but the undocumented stutter mode of the MCP16312 screwed it up. > >>>>>>>>> > >>>>>>>>> Chips these days. > >>>>>>>>> > >>>>>>>> > >>>>>>>> My latest fave is the TPS54302. It's a 6-pin SOT23, nice and dumb, and > >>>>>>>> behaves very well. > >>>>>>>> > >>>>>>>> There is no usable model (Web-bench never works for me) so I had to > >>>>>>>> breadboard the various compensations, but that's done now. > >>>>>>>> > >>>>>>>> > >>>>>>> Looks like a nice part, but distributor stock appears to be very thin. > >>>>>>> > >>>>>>> Cheers > >>>>>>> > >>>>>>> Phil Hobbs > >>>>>> > >>>>>> I'd better check on that. It's very similar to the AOZ part but, of > >>>>>> course, different pinout. > >>>>>> > >>>>>> > >>>>> Yeah, there's a big run on quite a few chips at the moment, it seems. > >>>>> The AOZ1282-1 is in "full production" but nobody has any more till at > >>>>> least January. It's the 400 mA, 1-MHz version of the vanilla 1282, > >>>>> which is a 1A, 500 kHz part. Faster is nice when you're coming off a > >>>>> 24V rail. > >>> > >>>> > >>>> We just nabbed 500 of the TI parts from Arrow. > >>> > >>> Which was about 40% of the total world supply at that point. Weird--you > >>> don't look at all like Bunker Hunt. ;) > >> > >> Maybe they will be the next bitcoin. > >> > >> > >>>> > >>>> The 54302 works fine making 24 into 5 or 3.3. It gets inefficient > >>>> making +1 (FPGA core voltage) from 24. For that, I went from 24 to 5, > >>>> then 5 to 1. > >>>> > >>>> The TI claims to run up to 3 amps, and it does, but it gets pretty > >>>> warm. 2.5 seems more prudent. Not bad for a SOT-23. > >>>> > >>>> It's not entirely clear how the heat gets out of this chip, so we hung > >>>> some copper on everything. > >>>> > >>>> https://www.dropbox.com/s/mxjunh0ykivkjys/P5_Regs_1.JPG?raw=1 > >>> > >>> Yup, vias are free, pours are cheap, but field fails are _expensive_. > >>> > >>> BTW we took your advice and standardized on the highest > >>> commonly-available wall wart voltage (+24). We use a pretty strict UVLO > >>> setting (19V) so that if somebody connects the wrong supply, nothing > >>> happens. > >> > >> Yeah, somebody might accidentally plug a 12v wart into a 6v box, but > >> it's unlikely anyone will have anything above 24, so no transzorbs > >> needed. Maybe reverse protection, though. > > I went looking for wall warts and found that 48V seemed to be the next > > 'standard' value. I built a gizmo with one. > > (Power plug gets pitted by arcs when it is disconnected 'hot'.) > > > > George H. > > 48V warts aren't at all common IME. Modems used to use 24VAC ones, but > there aren't many of those left. >Sure the arcing is not so nice. We like these 15W Phihong wall warts with different blades for different countries. https://phihong.com/assets/pdf/PSA15R.pdf I really wanted a 36V one, but I guess with DC switchers, people make what they need.> Cheers > > Phil Hobbs > > -- > Dr Philip C D Hobbs > Principal Consultant > ElectroOptical Innovations LLC / Hobbs ElectroOptics > Optics, Electro-optics, Photonics, Analog Electronics > Briarcliff Manor NY 10510 > > http://electrooptical.net > https://hobbs-eo.com
On 12/15/2017 10:53 AM, George Herold wrote:> On Thursday, December 14, 2017 at 8:53:36 PM UTC-5, John Larkin wrote: >> On Thu, 14 Dec 2017 19:59:23 -0500, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 12/14/2017 07:19 PM, John Larkin wrote: >>>> On Thu, 14 Dec 2017 17:02:41 -0500, Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> On 12/14/2017 04:42 PM, John Larkin wrote: >>>>>> On Thu, 14 Dec 2017 14:40:49 -0500, Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>> >>>>>>> On 12/14/2017 12:17 PM, John Larkin wrote: >>>>>>>> On Thu, 14 Dec 2017 09:45:17 -0500, Phil Hobbs >>>>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>>>> >>>>>>>>> Modern buck regulators seem to have way too many features that I can't >>>>>>>>> turn off or customize. >>>>>>>>> >>>>>>>>> The otherwise very nice AOZ1282-1 snookered me by having a 600-us fixed >>>>>>>>> short-circuit protection interval--it wouldn't start up into a 220 uF >>>>>>>>> capacitor, even with a very light load. Fortunately, switching to 22 uF >>>>>>>>> fixed it, and I had some with the right footprint. >>>>>>>>> >>>>>>>>> And then many go into stutter mode at light loads, e.g. the MCP16311. >>>>>>>>> Its brother, the MCP16312, is claimed to stay in vanilla PWM mode >>>>>>>>> throughout the load range, but the data sheet lies. That bit me once >>>>>>>>> when I was trying to make an isolated +24 -> +-5V converter for an >>>>>>>>> industrial control system, using two coupled inductors. Simulated >>>>>>>>> great, but the undocumented stutter mode of the MCP16312 screwed it up. >>>>>>>>> >>>>>>>>> Chips these days. >>>>>>>>> >>>>>>>> >>>>>>>> My latest fave is the TPS54302. It's a 6-pin SOT23, nice and dumb, and >>>>>>>> behaves very well. >>>>>>>> >>>>>>>> There is no usable model (Web-bench never works for me) so I had to >>>>>>>> breadboard the various compensations, but that's done now. >>>>>>>> >>>>>>>> >>>>>>> Looks like a nice part, but distributor stock appears to be very thin. >>>>>>> >>>>>>> Cheers >>>>>>> >>>>>>> Phil Hobbs >>>>>> >>>>>> I'd better check on that. It's very similar to the AOZ part but, of >>>>>> course, different pinout. >>>>>> >>>>>> >>>>> Yeah, there's a big run on quite a few chips at the moment, it seems. >>>>> The AOZ1282-1 is in "full production" but nobody has any more till at >>>>> least January. It's the 400 mA, 1-MHz version of the vanilla 1282, >>>>> which is a 1A, 500 kHz part. Faster is nice when you're coming off a >>>>> 24V rail. >>> >>>> >>>> We just nabbed 500 of the TI parts from Arrow. >>> >>> Which was about 40% of the total world supply at that point. Weird--you >>> don't look at all like Bunker Hunt. ;) >> >> Maybe they will be the next bitcoin. >> >> >>>> >>>> The 54302 works fine making 24 into 5 or 3.3. It gets inefficient >>>> making +1 (FPGA core voltage) from 24. For that, I went from 24 to 5, >>>> then 5 to 1. >>>> >>>> The TI claims to run up to 3 amps, and it does, but it gets pretty >>>> warm. 2.5 seems more prudent. Not bad for a SOT-23. >>>> >>>> It's not entirely clear how the heat gets out of this chip, so we hung >>>> some copper on everything. >>>> >>>> https://www.dropbox.com/s/mxjunh0ykivkjys/P5_Regs_1.JPG?raw=1 >>> >>> Yup, vias are free, pours are cheap, but field fails are _expensive_. >>> >>> BTW we took your advice and standardized on the highest >>> commonly-available wall wart voltage (+24). We use a pretty strict UVLO >>> setting (19V) so that if somebody connects the wrong supply, nothing >>> happens. >> >> Yeah, somebody might accidentally plug a 12v wart into a 6v box, but >> it's unlikely anyone will have anything above 24, so no transzorbs >> needed. Maybe reverse protection, though. > I went looking for wall warts and found that 48V seemed to be the next > 'standard' value. I built a gizmo with one. > (Power plug gets pitted by arcs when it is disconnected 'hot'.) > > George H.48V warts aren't at all common IME. Modems used to use 24VAC ones, but there aren't many of those left. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net https://hobbs-eo.com
On Thursday, December 14, 2017 at 8:53:36 PM UTC-5, John Larkin wrote:> On Thu, 14 Dec 2017 19:59:23 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > > >On 12/14/2017 07:19 PM, John Larkin wrote: > >> On Thu, 14 Dec 2017 17:02:41 -0500, Phil Hobbs > >> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> > >>> On 12/14/2017 04:42 PM, John Larkin wrote: > >>>> On Thu, 14 Dec 2017 14:40:49 -0500, Phil Hobbs > >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>> > >>>>> On 12/14/2017 12:17 PM, John Larkin wrote: > >>>>>> On Thu, 14 Dec 2017 09:45:17 -0500, Phil Hobbs > >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: > >>>>>> > >>>>>>> Modern buck regulators seem to have way too many features that I can't > >>>>>>> turn off or customize. > >>>>>>> > >>>>>>> The otherwise very nice AOZ1282-1 snookered me by having a 600-us fixed > >>>>>>> short-circuit protection interval--it wouldn't start up into a 220 uF > >>>>>>> capacitor, even with a very light load. Fortunately, switching to 22 uF > >>>>>>> fixed it, and I had some with the right footprint. > >>>>>>> > >>>>>>> And then many go into stutter mode at light loads, e.g. the MCP16311. > >>>>>>> Its brother, the MCP16312, is claimed to stay in vanilla PWM mode > >>>>>>> throughout the load range, but the data sheet lies. That bit me once > >>>>>>> when I was trying to make an isolated +24 -> +-5V converter for an > >>>>>>> industrial control system, using two coupled inductors. Simulated > >>>>>>> great, but the undocumented stutter mode of the MCP16312 screwed it up. > >>>>>>> > >>>>>>> Chips these days. > >>>>>>> > >>>>>> > >>>>>> My latest fave is the TPS54302. It's a 6-pin SOT23, nice and dumb, and > >>>>>> behaves very well. > >>>>>> > >>>>>> There is no usable model (Web-bench never works for me) so I had to > >>>>>> breadboard the various compensations, but that's done now. > >>>>>> > >>>>>> > >>>>> Looks like a nice part, but distributor stock appears to be very thin. > >>>>> > >>>>> Cheers > >>>>> > >>>>> Phil Hobbs > >>>> > >>>> I'd better check on that. It's very similar to the AOZ part but, of > >>>> course, different pinout. > >>>> > >>>> > >>> Yeah, there's a big run on quite a few chips at the moment, it seems. > >>> The AOZ1282-1 is in "full production" but nobody has any more till at > >>> least January. It's the 400 mA, 1-MHz version of the vanilla 1282, > >>> which is a 1A, 500 kHz part. Faster is nice when you're coming off a > >>> 24V rail. > > > >> > >> We just nabbed 500 of the TI parts from Arrow. > > > >Which was about 40% of the total world supply at that point. Weird--you > >don't look at all like Bunker Hunt. ;) > > Maybe they will be the next bitcoin. > > > >> > >> The 54302 works fine making 24 into 5 or 3.3. It gets inefficient > >> making +1 (FPGA core voltage) from 24. For that, I went from 24 to 5, > >> then 5 to 1. > >> > >> The TI claims to run up to 3 amps, and it does, but it gets pretty > >> warm. 2.5 seems more prudent. Not bad for a SOT-23. > >> > >> It's not entirely clear how the heat gets out of this chip, so we hung > >> some copper on everything. > >> > >> https://www.dropbox.com/s/mxjunh0ykivkjys/P5_Regs_1.JPG?raw=1 > > > >Yup, vias are free, pours are cheap, but field fails are _expensive_. > > > >BTW we took your advice and standardized on the highest > >commonly-available wall wart voltage (+24). We use a pretty strict UVLO > >setting (19V) so that if somebody connects the wrong supply, nothing > >happens. > > Yeah, somebody might accidentally plug a 12v wart into a 6v box, but > it's unlikely anyone will have anything above 24, so no transzorbs > needed. Maybe reverse protection, though.I went looking for wall warts and found that 48V seemed to be the next 'standard' value. I built a gizmo with one. (Power plug gets pitted by arcs when it is disconnected 'hot'.) George H.> > This one is nice, rated 36 watts with good margin. > > https://www.digikey.com/product-detail/en/cui-inc/SMI36-24-V-P6/102-3833-ND/5417799 > > Comes with all the international adapters. > > > -- > > John Larkin Highland Technology, Inc > picosecond timing precision measurement > > jlarkin att highlandtechnology dott com > http://www.highlandtechnology.com
On Thu, 14 Dec 2017 19:59:23 -0500, Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:>On 12/14/2017 07:19 PM, John Larkin wrote: >> On Thu, 14 Dec 2017 17:02:41 -0500, Phil Hobbs >> <pcdhSpamMeSenseless@electrooptical.net> wrote: >> >>> On 12/14/2017 04:42 PM, John Larkin wrote: >>>> On Thu, 14 Dec 2017 14:40:49 -0500, Phil Hobbs >>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>> >>>>> On 12/14/2017 12:17 PM, John Larkin wrote: >>>>>> On Thu, 14 Dec 2017 09:45:17 -0500, Phil Hobbs >>>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>>> >>>>>>> Modern buck regulators seem to have way too many features that I can't >>>>>>> turn off or customize. >>>>>>> >>>>>>> The otherwise very nice AOZ1282-1 snookered me by having a 600-us fixed >>>>>>> short-circuit protection interval--it wouldn't start up into a 220 uF >>>>>>> capacitor, even with a very light load. Fortunately, switching to 22 uF >>>>>>> fixed it, and I had some with the right footprint. >>>>>>> >>>>>>> And then many go into stutter mode at light loads, e.g. the MCP16311. >>>>>>> Its brother, the MCP16312, is claimed to stay in vanilla PWM mode >>>>>>> throughout the load range, but the data sheet lies. That bit me once >>>>>>> when I was trying to make an isolated +24 -> +-5V converter for an >>>>>>> industrial control system, using two coupled inductors. Simulated >>>>>>> great, but the undocumented stutter mode of the MCP16312 screwed it up. >>>>>>> >>>>>>> Chips these days. >>>>>>> >>>>>> >>>>>> My latest fave is the TPS54302. It's a 6-pin SOT23, nice and dumb, and >>>>>> behaves very well. >>>>>> >>>>>> There is no usable model (Web-bench never works for me) so I had to >>>>>> breadboard the various compensations, but that's done now. >>>>>> >>>>>> >>>>> Looks like a nice part, but distributor stock appears to be very thin. >>>>> >>>>> Cheers >>>>> >>>>> Phil Hobbs >>>> >>>> I'd better check on that. It's very similar to the AOZ part but, of >>>> course, different pinout. >>>> >>>> >>> Yeah, there's a big run on quite a few chips at the moment, it seems. >>> The AOZ1282-1 is in "full production" but nobody has any more till at >>> least January. It's the 400 mA, 1-MHz version of the vanilla 1282, >>> which is a 1A, 500 kHz part. Faster is nice when you're coming off a >>> 24V rail. > >> >> We just nabbed 500 of the TI parts from Arrow. > >Which was about 40% of the total world supply at that point. Weird--you >don't look at all like Bunker Hunt. ;)Maybe they will be the next bitcoin.>> >> The 54302 works fine making 24 into 5 or 3.3. It gets inefficient >> making +1 (FPGA core voltage) from 24. For that, I went from 24 to 5, >> then 5 to 1. >> >> The TI claims to run up to 3 amps, and it does, but it gets pretty >> warm. 2.5 seems more prudent. Not bad for a SOT-23. >> >> It's not entirely clear how the heat gets out of this chip, so we hung >> some copper on everything. >> >> https://www.dropbox.com/s/mxjunh0ykivkjys/P5_Regs_1.JPG?raw=1 > >Yup, vias are free, pours are cheap, but field fails are _expensive_. > >BTW we took your advice and standardized on the highest >commonly-available wall wart voltage (+24). We use a pretty strict UVLO >setting (19V) so that if somebody connects the wrong supply, nothing >happens.Yeah, somebody might accidentally plug a 12v wart into a 6v box, but it's unlikely anyone will have anything above 24, so no transzorbs needed. Maybe reverse protection, though. This one is nice, rated 36 watts with good margin. https://www.digikey.com/product-detail/en/cui-inc/SMI36-24-V-P6/102-3833-ND/5417799 Comes with all the international adapters. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On 12/14/2017 07:19 PM, John Larkin wrote:> On Thu, 14 Dec 2017 17:02:41 -0500, Phil Hobbs > <pcdhSpamMeSenseless@electrooptical.net> wrote: > >> On 12/14/2017 04:42 PM, John Larkin wrote: >>> On Thu, 14 Dec 2017 14:40:49 -0500, Phil Hobbs >>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>> >>>> On 12/14/2017 12:17 PM, John Larkin wrote: >>>>> On Thu, 14 Dec 2017 09:45:17 -0500, Phil Hobbs >>>>> <pcdhSpamMeSenseless@electrooptical.net> wrote: >>>>> >>>>>> Modern buck regulators seem to have way too many features that I can't >>>>>> turn off or customize. >>>>>> >>>>>> The otherwise very nice AOZ1282-1 snookered me by having a 600-us fixed >>>>>> short-circuit protection interval--it wouldn't start up into a 220 uF >>>>>> capacitor, even with a very light load. Fortunately, switching to 22 uF >>>>>> fixed it, and I had some with the right footprint. >>>>>> >>>>>> And then many go into stutter mode at light loads, e.g. the MCP16311. >>>>>> Its brother, the MCP16312, is claimed to stay in vanilla PWM mode >>>>>> throughout the load range, but the data sheet lies. That bit me once >>>>>> when I was trying to make an isolated +24 -> +-5V converter for an >>>>>> industrial control system, using two coupled inductors. Simulated >>>>>> great, but the undocumented stutter mode of the MCP16312 screwed it up. >>>>>> >>>>>> Chips these days. >>>>>> >>>>> >>>>> My latest fave is the TPS54302. It's a 6-pin SOT23, nice and dumb, and >>>>> behaves very well. >>>>> >>>>> There is no usable model (Web-bench never works for me) so I had to >>>>> breadboard the various compensations, but that's done now. >>>>> >>>>> >>>> Looks like a nice part, but distributor stock appears to be very thin. >>>> >>>> Cheers >>>> >>>> Phil Hobbs >>> >>> I'd better check on that. It's very similar to the AOZ part but, of >>> course, different pinout. >>> >>> >> Yeah, there's a big run on quite a few chips at the moment, it seems. >> The AOZ1282-1 is in "full production" but nobody has any more till at >> least January. It's the 400 mA, 1-MHz version of the vanilla 1282, >> which is a 1A, 500 kHz part. Faster is nice when you're coming off a >> 24V rail.> > We just nabbed 500 of the TI parts from Arrow.Which was about 40% of the total world supply at that point. Weird--you don't look at all like Bunker Hunt. ;)> > The 54302 works fine making 24 into 5 or 3.3. It gets inefficient > making +1 (FPGA core voltage) from 24. For that, I went from 24 to 5, > then 5 to 1. > > The TI claims to run up to 3 amps, and it does, but it gets pretty > warm. 2.5 seems more prudent. Not bad for a SOT-23. > > It's not entirely clear how the heat gets out of this chip, so we hung > some copper on everything. > > https://www.dropbox.com/s/mxjunh0ykivkjys/P5_Regs_1.JPG?raw=1Yup, vias are free, pours are cheap, but field fails are _expensive_. BTW we took your advice and standardized on the highest commonly-available wall wart voltage (+24). We use a pretty strict UVLO setting (19V) so that if somebody connects the wrong supply, nothing happens. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC / Hobbs ElectroOptics Optics, Electro-optics, Photonics, Analog Electronics Briarcliff Manor NY 10510 http://electrooptical.net http://hobbs-eo.com