Post by thread:voltage regulator question

Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. I'm finding very few options in the datasheets. PCB size is a premium. Reliability is SUPER important, component cost/complexity is secondary. Ideas? Thanks! Andy ================================================================== Montana Design Tech Support - http://www.montanadesign.com ==================================================================

Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. That's well within the range of telco-oriented dc/dc converters (which have input voltage of typically 36-72V), although those tend to start with a particular package size and cram as many watts as possible into them, rather than picking a number of watts and making the package as small as possible. For example, in about the size of a 24pin DIP, Datel has a 3W converter. I suspect you had something much smaller in mind... BillW

The TL317CD is the SO8 version of a LM317 regulator. Max 40 V and 100 mA, but - I guess it ould run too hot... You don't have room to help this little fellow out do you ?; with a zener in series to the input or soething ? Anyway - just look at the size of a SO8 product. Whatever it contains, it needs thermal assistance with black aluminium somehow in my opinion. Can you fit a cooler on top ? Sven -----Ursprungligt meddelande----- FrŒn: Andy Kunz <spam_OUTsupportTakeThisOuTMONTANADESIGN.COM> Till: .....PICLISTKILLspam@spam@MITVMA.MIT.EDU <PICLISTKILLspamMITVMA.MIT.EDU> Datum: den 14 maj 1999 20:31 €mne: voltage regulator question {Quote hidden}>Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? > 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. > >I'm finding very few options in the datasheets. > >PCB size is a premium. Reliability is SUPER important, component >cost/complexity is secondary. > >Ideas? > >Thanks! > >Andy > >================================================================== > Montana Design Tech Support - http://www.montanadesign.com >================================================================== >

>The TL317CD is the SO8 version of a LM317 regulator. Max 40 V and 100 mA, >but - I guess it ould run too hot... Thnks. I'll check. >You don't have room to help this little fellow out do you ?; with a zener >in series to the input or soething ? Room? It's about 1cm square. A Zener would be possible, but it'll still be warm. >Anyway - just look at the size of a SO8 product. Whatever it contains, it >needs thermal assistance with black aluminium somehow in my opinion. Can you >fit a cooler on top ? Cooler? HA! Andy ================================================================== Montana Design Tech Support - http://www.montanadesign.com ==================================================================

Hi again Andy , A whole sq cm ? That is not so bad. An SO8 and a zener would find room. Not knowing your product, and how this PCB is to be used, I am not joking, as I suggest that you should look for a 1x1 cm cooler. Maybe 6 - 8 mm high. Just guessing - but a block like that (with small "fins" of course) would just get luke warm at 2 Watts. That's how I would look at it. Such coolers are available. And again - 2 Watts is always 2 Watts. Whatever the compmonent. Color, material and size counts. But again - I don't know if that is to tall, impossible to affix, or whatever. Depending on quantity, a custom designed cooler might be a solution. Best Regards Sven -----Ursprungligt meddelande----- FrŒn: Andy Kunz <.....supportKILLspam.....MONTANADESIGN.COM> Till: EraseMEPICLISTspam_OUTTakeThisOuTMITVMA.MIT.EDU <PICLISTspam_OUTMITVMA.MIT.EDU> Datum: den 14 maj 1999 22:04 €mne: Re: SV: voltage regulator question {Quote hidden}>>The TL317CD is the SO8 version of a LM317 regulator. Max 40 V and 100 mA, >>but - I guess it ould run too hot... > >Thnks. I'll check. > >>You don't have room to help this little fellow out do you ?; with a zener >>in series to the input or soething ? > >Room? It's about 1cm square. A Zener would be possible, but it'll still >be warm. > >>Anyway - just look at the size of a SO8 product. Whatever it contains, it >>needs thermal assistance with black aluminium somehow in my opinion. Can you >>fit a cooler on top ? > >Cooler? HA! > >Andy > >================================================================== > Montana Design Tech Support - http://www.montanadesign.com >================================================================== >

You will find power supply chips for Telecom circuits does this. First try siliconix, then maixm, linear tech, SGS, to name few. U/Interface on ISDN is powered from 48V to 5V converters. Regards, Jay PS If I find part numbers I will post it next week. At 14:28 14/05/99 -0400, you wrote: {Quote hidden}>Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? > 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. > >I'm finding very few options in the datasheets. > >PCB size is a premium. Reliability is SUPER important, component >cost/complexity is secondary. > >Ideas? > >Thanks! > >Andy > >================================================================== > Montana Design Tech Support - http://www.montanadesign.com >================================================================== > > >

I am doing something similar to this with an lm3480, but the entire PCB is encased in a heat conductive potting compound (an epoxy) On Fri, 14 May 1999, MILTON MEDICINTEKNIK KB wrote: {Quote hidden}> Hi again Andy , > > A whole sq cm ? That is not so bad. An SO8 and a zener would find room. > > Not knowing your product, and how this PCB is to be used, I am not joking, as I suggest that you should look for a 1x1 cm cooler. Maybe 6 - 8 mm high. Just guessing - but a block like that (with small "fins" of course) would just get luke warm at 2 Watts. That's how I would look at it. Such coolers are available. And again - 2 Watts is always 2 Watts. Whatever the compmonent. Color, material and size counts. > > But again - I don't know if that is to tall, impossible to affix, or whatever. Depending on quantity, a custom designed cooler might be a solution. > > Best Regards > > > Sven > -----Ursprungligt meddelande----- > Från: Andy Kunz <@spam@supportKILLspamMONTANADESIGN.COM> > Till: KILLspamPICLISTKILLspamMITVMA.MIT.EDU <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> > Datum: den 14 maj 1999 22:04 > Ämne: Re: SV: voltage regulator question > > > >>The TL317CD is the SO8 version of a LM317 regulator. Max 40 V and 100 mA, > >>but - I guess it ould run too hot... > > > >Thnks. I'll check. > > > >>You don't have room to help this little fellow out do you ?; with a zener > >>in series to the input or soething ? > > > >Room? It's about 1cm square. A Zener would be possible, but it'll still > >be warm. > > > >>Anyway - just look at the size of a SO8 product. Whatever it contains, it > >>needs thermal assistance with black aluminium somehow in my opinion. Can you > >>fit a cooler on top ? > > > >Cooler? HA! > > > >Andy > > > >================================================================== > > Montana Design Tech Support - http://www.montanadesign.com > >================================================================== > > >

What about National's HV versions of simple switcher. LM2594HV is 5V, SOIC 8pin, max Vin 60V. On Fri, 14 May 1999, Andy Kunz wrote: {Quote hidden}> Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? > 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. > > I'm finding very few options in the datasheets. > > PCB size is a premium. Reliability is SUPER important, component > cost/complexity is secondary. > > Ideas? > > Thanks! > > Andy > > ================================================================== > Montana Design Tech Support - http://www.montanadesign.com > ================================================================== >

At 02:28 PM 5/14/99 -0400, you wrote: >Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? > 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. > >I'm finding very few options in the datasheets. > >PCB size is a premium. Reliability is SUPER important, component >cost/complexity is secondary. > Check with National Semi. They have variants of the 78xx series in a "DPAK" configuration. Gets over 30 volts on the inputs, but I don't recall how far over. Unless you need a really WIDE input range, put a power zener in series to drop the voltage to an acceptable level. A 30 volt .05 A zener would need to be 2 watts and would drop your 40 volts to 15 which most SMT devices will handle (16 volt MAX). A note to everyone: Check out the TELCOM TC55 series! 200 mA output, 3 microamps quiescent current, VERY low dropout voltage, and CHEAP. SOT-23 package. We plan on buying a reel of 5 and 3.3 volt parts and would consider selling in smaller quantities. This is a really good part! **************************************************************************** ******** All legitimate attachments to this email will be clearly identified in the text. Please note our new address and phone numbers. William K. Borsum, P.E. DASCOR P.O.Box 462885 Escondido, CA 92046-2885 V&M&F) 760-796-7785 Direct) 760-796-7788 <spamBeGoneborsumspamBeGonedascor.com>

On Fri, 14 May 1999 20:15:18 -0700, you wrote: >At 02:28 PM 5/14/99 -0400, you wrote: >>Anybody know of a SMT regulator which can handle 45V input, 5V/50mA output? >> 40V * 50mA = 2W - an awful lot for a tiny PCB to handle. >> >>I'm finding very few options in the datasheets. >> >>PCB size is a premium. Reliability is SUPER important, component >>cost/complexity is secondary. If reliability is important, you don't want to be dissipating 2 watts, especially in a small space. Use a switcher, e.g. nat. semi. LM2574HV which takes up to 60V input and comes in a 14 pin SO or 8 pin DIP. Although it will take more board space for components, you'll save the space you'd otherwise use on the heatsinking you'd need for a linear reg, as well as drastically reducing the power draw from the 40V supply. At 50mA o/p you should be able to use a pretty small inductor, diode and caps.

Andy A series resistor will get the majority of the dissipation away from the IC. You can let the regulator drop only a few volts when you are at full design current. At low or no current the regulator will take most of the dissipation and voltage but it will be less critical. You nominated SMT but the resistors may not have to be. 4 x Philips SFR16 series resistors will handle max required dissipation (and will mount in about 6mm x 3mm space each if necessary) and there are of course lots of metal film resistors which will handle this power in a single unit. regards Russell McMahon. {Original Message removed}