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???
07/07/09 18:49
Modified:
  07/07/09 18:51
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 		 #166843 - Have you considered a pMOSFET?
Responding to: ???'s previous message
Some of these have very low threshold voltages, hence will operate just fine under control of an MCU at 3V3. They're not always as cheap as cheap PNP's, but they are pretty cheap. If you add the on-resistance to the load forward voltage, you may not even need a series resistor. Don't count on it, but if there's enough margin, well, it might work just fine.

RE


List of 33 messages in thread
TopicAuthorDate
Driving a 5 v PNP with 3.3 volts pin            01/01/70 00:00      
   Diagram ?            01/01/70 00:00      
      Sketch..            01/01/70 00:00      
         Steve..            01/01/70 00:00      
            Why push-pull?            01/01/70 00:00      
               Thanks Rob            01/01/70 00:00      
               Very much depending on chip            01/01/70 00:00      
                  Yeah, but ...            01/01/70 00:00      
                     Better always add a note for potentially dangerous methods            01/01/70 00:00      
                        Is that my responsability?            01/01/70 00:00      
                  Westermark            01/01/70 00:00      
                     Erik did exmplain            01/01/70 00:00      
                        Sorry Westermark..            01/01/70 00:00      
         KISS            01/01/70 00:00      
   If it has not to be a PNP...            01/01/70 00:00      
      Relay has to be driven..            01/01/70 00:00      
         since I would never do that ...            01/01/70 00:00      
            Open drain pulled up to 5V..            01/01/70 00:00      
               did you read my post            01/01/70 00:00      
                  Deep waters            01/01/70 00:00      
                     OK, more            01/01/70 00:00      
                        I missed this post..            01/01/70 00:00      
      BC556 would turn on, wouldn't it?            01/01/70 00:00      
         It wouldn't. Sorry.            01/01/70 00:00      
   Have you considered a pMOSFET?            01/01/70 00:00      
      Yep, I second that! Use a FET            01/01/70 00:00      
         Have you considered that he must drive a 5V relay?            01/01/70 00:00      
            Does that really matter?            01/01/70 00:00      
               To what do you connect the source of this pMOSFET??            01/01/70 00:00      
                  It's the switched drain current that does the work            01/01/70 00:00      
                     Of course, it does! But...            01/01/70 00:00      
                        One could also use a "switch" ...            01/01/70 00:00      
                           Yes, that's safe!            01/01/70 00:00      

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