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???
09/06/10 15:57
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 		 #178460 - Still need for power - but varying voltages and low loss
Responding to: ???'s previous message
Many new devices are not satisfied with any "standardized" 5V anymore.

They may need 1.4V for a processor core. 3.3V for most I/O signals. 4.2V for GSM. 5V for GPS.

Next thing is that they may accept 9V .. 40V DC in which case the losses in the power supply can be very high.

And lower voltages means higher currents for the same power.

Let's say you have a device with USB. So maybe 5V 0.5A required.
And then a CF slot, type II means 500mA more.
Add a 3G module, a couple of relays, ...

Quite soon you get something that draws 250mA from 12V on average but may consume 15W or more when all peripherials are at their max.

So in the end, you don't need any PC-class hardware to have power needs similar to these 5V 5A regulators. Just that the small box gets hot enough from powering everything in it without the need for having a burning hot serial regulator.

In many situations the heat sink together with cost of mounting the mechanics will be way higher than the cost of a switching mode regulator - and then the switching mode regulator will save money for every Wh consumed by the unit.

List of 21 messages in thread
TopicAuthorDate
LM78H05K Datasheet really exists?            01/01/70 00:00      
   Searching for Datasheets            01/01/70 00:00      
      photo            01/01/70 00:00      
         Yes, that's National Semiconductor            01/01/70 00:00      
            You are right again...            01/01/70 00:00      
               I think the "H" may be because it is 5A isnt it?            01/01/70 00:00      
                  from the days of burning your fingers            01/01/70 00:00      
                      I fail to see a modern design needing that amount...            01/01/70 00:00      
                        qualify            01/01/70 00:00      
                           Still need for power - but varying voltages and low loss            01/01/70 00:00      
                           12V the big favourite in a PC            01/01/70 00:00      
                     Killed off by switchers            01/01/70 00:00      
                        The heat was always a challenge with high-power linears            01/01/70 00:00      
                  Disapointed but clear.            01/01/70 00:00      
                     How so?            01/01/70 00:00      
                     You can make your own ...            01/01/70 00:00      
                        re: You can make your own            01/01/70 00:00      
                           Yes, they did, and those sheets were excellent!            01/01/70 00:00      
   the first mistake            01/01/70 00:00      
   Fairchild was the original manufacturer            01/01/70 00:00      
   these parts are hybrids ... so you can synthesize them            01/01/70 00:00      

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