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Circuit for source HDMI 5V



		

			

									
					    phan
					
							

			
				
									
											
			
			
				
    
			
			
			    	
			                    
                
				                on Dec 10, 2014 
				
			
			
		
    

				
		
    
		    		    
		    
		    	
			
    Hi,
    
 
    I am looking for a simple device/circuitry that will take internal 5VDC and provide HDMI compliance 5V to the HDMI connector (4.8-5.3V, 500mA max). 
    
 
    From the ADV7842/ADV7511 eval schematic, it is just a simple connection to internal 5V, but in reviewing the HDMI spec, this is a hard requirement (Shall) so I need to provide a protection scheme. Resettable fuses are out of picture because of high drop.
    
 
    Suggestions are appreciated.
    
 
    Thanks,
    
 
    Tai
    
									
			        
		
    

				
						
        

    
    Tags: 
                                            
                 hdmi 5v source device
                
                                
            
    
    
    

		
    
			
						
									
									
						
						
			
			
			
			
		
    

        
        

					
    
			
    


    
















    
	
    
	
    
					



			








	
	
	
	



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							FormerMember
					
      
		
      
			
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									FormerMember
							        
			
			
			
    
            
			                            
                                                                                                                        
            
				
			
            
					
    
	
    

		
		
    
					
    HDMI 1.4b spec says the source shall provide +5V power with over-current protection of no more that 0.5A.  All HDMI source shall be able to supply a minimum of 55mA.  The sink shall not draw more and 50mA.
    
 
    So there are several methods I've seen to meet this:
    
 
    1) Hard tie to source +5V rail.  Bad plan since a short at the sink will bring down the source
    
 
    2) Use PTC resistors (resettable fuse).  To meet the minimum voltage of 50mA load the fuse needs to be 0.75A which exceeds the maximum of 0.5A.  This also is a bad plan
    
 
    3) If you have greater than 6V available on the source board the use and LDO like the ADP3335ARMZ-5 to drive the output.  It provides the required 5V and will current limit at 100mA or thermally or over-current conditions.  Also provides easy way to allow the source to turn off and on the DDC_5V rail.  Down side is it needs a >6V rail on the source board to work from
    
 
    4) Use an AD9334 specifically designed 3.3V to 5V charge pump meant to drive HDMI 5V signals.  Runs from 3.3V and has enable switch to turn 5V on and off.  This is probably the best solution
    
 
    AD9394 datasheet and product info | 5 V Charge Pump HDMI Tx Companion Chip | Analog/HDMI/DVI Interfaces | Analog Devices
    
 
    5) Other vendors have current limiting HDMI interfaces which include ESD protection form the TMDS lines and current limit p-channel fet for the 5V signal.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    


	



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							FormerMember
					
      
		
      
			
													0
							
			
				
									FormerMember
							        
			
			
			
    
            
			                            
                                                                                                                        
            
				
			
            
					
    
	
    

		
		
    
					
    HDMI 1.4b spec says the source shall provide +5V power with over-current protection of no more that 0.5A.  All HDMI source shall be able to supply a minimum of 55mA.  The sink shall not draw more and 50mA.
    
 
    So there are several methods I've seen to meet this:
    
 
    1) Hard tie to source +5V rail.  Bad plan since a short at the sink will bring down the source
    
 
    2) Use PTC resistors (resettable fuse).  To meet the minimum voltage of 50mA load the fuse needs to be 0.75A which exceeds the maximum of 0.5A.  This also is a bad plan
    
 
    3) If you have greater than 6V available on the source board the use and LDO like the ADP3335ARMZ-5 to drive the output.  It provides the required 5V and will current limit at 100mA or thermally or over-current conditions.  Also provides easy way to allow the source to turn off and on the DDC_5V rail.  Down side is it needs a >6V rail on the source board to work from
    
 
    4) Use an AD9334 specifically designed 3.3V to 5V charge pump meant to drive HDMI 5V signals.  Runs from 3.3V and has enable switch to turn 5V on and off.  This is probably the best solution
    
 
    AD9394 datasheet and product info | 5 V Charge Pump HDMI Tx Companion Chip | Analog/HDMI/DVI Interfaces | Analog Devices
    
 
    5) Other vendors have current limiting HDMI interfaces which include ESD protection form the TMDS lines and current limit p-channel fet for the 5V signal.
    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    





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