ImperialGuardWH40K Posted July 15, 2006 Report Share Posted July 15, 2006 Hello, Quote Link to comment Share on other sites More sharing options...
hotwaterwizard Posted July 15, 2006 Report Share Posted July 15, 2006 A part number would help. The answer to your question:One rating is with a heat sink and the lower is without a heatsink.Here is the datasheet.http://www.jameco.com/wcsstore/Jameco/Products/ProdDS/51246.pdf Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 15, 2006 Report Share Posted July 15, 2006 You can buy a lot of voltage regulators. 7805 is 5V, 7809 is 9V, 7812 is 12V and 7815 is 15V.You can buy them in a small plastic case and their max current is 100mA or a larger TO-220 case that can be bolted to a heatsink and their max current is 500mA and 1A.Current in a load resistor changes proportionally with voltage. A voltage regulator can supply as much current as it is made for. Quote Link to comment Share on other sites More sharing options...
Theatronics Posted July 16, 2006 Report Share Posted July 16, 2006 Remember your basics.P = E * I. If the Voltage into the chip is 9V and the voltage out is 5 then there is a 4V drop across the part.If the current flowing is 250ma then the wattage being expended at that part is250ma * 4V = 1WIf you drop that part in Liquid N (Assuming it can operate at that temp)You would get a MUCH higher Wattage beause the heat wouldn't melt the part down.Current carrying capicity is really all about how much HEAT a part can handle or get rid of. High current parts are usually large because they need to sink more heat.-Mike Quote Link to comment Share on other sites More sharing options...
Theatronics Posted July 16, 2006 Report Share Posted July 16, 2006 close,I think they just put the same part in a cheaper package.there is no differance between a 7805 in a TO-220 case or a TO-92 case.They are the exact same die. But the smaller TO-92 case will pop likea firecracker if you try to pull 2 amps through it.-Mike Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 16, 2006 Report Share Posted July 16, 2006 I think they just put the same part in a cheaper package.there is no differance between a 7805 in a TO-220 case or a TO-92 case.They are the exact same die. Quote Link to comment Share on other sites More sharing options...
Theatronics Posted July 16, 2006 Report Share Posted July 16, 2006 I've blown them up. :omagic smoke escaped, parts flew, blown up.That protection stuff works for well designed circuits.when you just plain abuse them, they go poof.-Mike Quote Link to comment Share on other sites More sharing options...
audioguru Posted July 16, 2006 Report Share Posted July 16, 2006 You can overload or short the output of a regulator. It will limit the current, get hotter and hotter and if the heatsink isn't big enough then the regulator will shut down. After it cools it will begin working again.It isn't recommended to leave a regulator cycling like that because of the thermal stress of it heating and cooling so many times. Quote Link to comment Share on other sites More sharing options...
Theatronics Posted July 16, 2006 Report Share Posted July 16, 2006 Just in case you wondered.The inside of a 7805 looks like this.(Sort of).Depends on the manufacturer.-Mike Quote Link to comment Share on other sites More sharing options...
ante Posted July 16, 2006 Report Share Posted July 16, 2006 I've blown them up. :omagic smoke escaped, parts flew, blown up.That protection stuff works for well designed circuits.when you just plain abuse them, they go poof.-MikeThere is at least one way to do this; reverse the polarity on the output! Example; put a charged capacitor the wrong way across the output! Use safety goggles for this one! 8) Quote Link to comment Share on other sites More sharing options...
indulis Posted July 16, 2006 Report Share Posted July 16, 2006 The die will be the same, only the current limit point will be trimmed (laser) to a different point. The carrier size is for heat. Quote Link to comment Share on other sites More sharing options...
c3r14l.k1l4 Posted July 16, 2006 Report Share Posted July 16, 2006 How is it that 5 volts could output 250mA and 1 amp?Because those devices are current limited (it's like they have resistors in series inside them). They wont give you more current for the purpose of not exceeding the maximum rating power (humm, burn :D). Quote Link to comment Share on other sites More sharing options...
indulis Posted July 17, 2006 Report Share Posted July 17, 2006 That is correct, they do have resisistors inside of them that are trimmed with lasers when the wafer is being tested. BTW- there are capacitors in there too, and some even have inductors. Quote Link to comment Share on other sites More sharing options...
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