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SSM2019 Production
The SSM2019 is a latest generation audio preamplifier, combining SSM preamplifier design expertise with advanced processing. The result is excellent audio...
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SSM2019 on Analog.com

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SSM2019 circuit drops output after a given amount of time

		
	
				

			

									
					    bdayson
					
							

            
            			
				
									
											
			
			
				
			
			
			    	
			                    
                
				                on May 22, 2025 
				
			
			
		

		
		                     
				
        		

		    
		    		    

		      		            		        
Category: Hardware

    		        		            		    
Product Number:  SSM2019  

    		        		    		    

		    		    
		    			

			    
I've designed a SSM2019 MEMS mic preamp circuit, however after around 3 minutes, the output drops out, as shown in the oscilloscope images. My first thought was that this would be thermal, but turning the power supply off and on again rapidly resets the state and gives another 3 minutes, so I don't think this is the case. Attached is the schematic and PCB. It is being driven by a signal generator on IN+ and GND, with IN- shorted to GND. The power supply is a TEC 2-2423WI isolated DC-DC power supply block, which is being powered by a bench top PSU. Just before the audio drops out, power draw increases by 0.07A.




    

			

			
									
		                             
                        

    

                                            
                 hardware
                
                                                    
                 Microphone Pre-Amp Audio Interfaces
                
                                                    
                 Audio Amplifiers
                
                                                    
                 ssm2019
                
                                                    
                 audio
                
                                
            

    
    
		


				
				        
        		

			
						
									
												
			
			
                        
                                    
                        
                        
                        
            
			            
						
						
			
			
			
			
		


        
        
        
    
					

			





















	

	

					



			


				
	









	
    
	

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    •  Analog Employees  
    •  Super User  
    
            
						
                            
            
            				
            
                on May 22, 2025 4:52 PM
            
            
						
			            		
    
		
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    Hello bdayson,
    

    There are a couple of things that peaked my interest. 
    

    First, what is the VCC and VEE voltage you are using? I did not see that in the schematics you posted. 
    

    

    On the Microphone input section of the schematic:
    

    What is the voltage on the points labeled DC+ and DC-? It is strange that the polarized caps are both in the same direction. 
    

    Is the header J1 connecting to the MEMS mic?
    

    How is the mic powered? Is it an analog MEMS mic? 
    

    All MEMS mics I have worked with have a digital output not analog. Provide a link to the mic you are using.
    

    The IN+ seems to be just floating and not referenced to anything. I think however you are powering the mic is slowly draining off or rising up and then it stops working. 
    

    Dave T
    

    
			
    

		
			
	      

		
		
	
    
	
    
		
    
			
		
    
	
    
	
    
		
						
						
				
						
				
				
		
		
    
			
		
    
	
    

    

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