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Original question:

TLC59108: setting GRPPWM register to "0" illuminates all LEDs to full brightness

TLC59108: Group fully ON with GRPPWM = 00h

Damien Drix
Prodigy 30 points
Part Number: TLC59108

Hi TI,

I have exactly the same problem as a previous customer: e2e.ti.com/.../723439

If I write 01h to GRPPWM, the group brightness is very low as expected.

But if I write 00h to GRPPWM, the group is fully ON. I can confirm I read back 00h from the register.

Here's the full config:

REG_0x00: 0b00000001
REG_0x01: 0b00000000
REG_0x02: 0b11110100
REG_0x03: 0b11101100
REG_0x04: 0b11001100
REG_0x05: 0b11111100
REG_0x06: 0b00000100
REG_0x07: 0b00000100
REG_0x08: 0b00000101
REG_0x09: 0b00000010
REG_0x0A: 0b00000000
REG_0x0B: 0b00000000
REG_0x0C: 0b11111111
REG_0x0D: 0b10111010
REG_0x0E: 0b10010010
REG_0x0F: 0b10010100
REG_0x10: 0b10011000
REG_0x11: 0b10010000
REG_0x12: 0b11100111

Regards

  • 0
    Prodigy 30 points

    I have investigated further and it seems the problem occurs when transitioning too fast from a high group brightness to a zero group brightness.

    Eg. this works: (LEDs are off)

    GRPPWM = 100
GRPPWM = 0

    This works:

    GRPPWM = 255
GRPPWM = 1

    This does not work: (LEDs still ON)

    GRPPWM = 250
GRPPWM = 0

    This works:

    GRPPWM = 250
GRPPWM = 10
<10 ms wait>
GRPPWM = 0


    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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						in reply to Damien Drix
					
									
    
	
    
	                                    
                      
    
                        
                          TI__Genius
                        12915 points
                      
    
                          
                   		
		
    
					
    Hi DamienD,
    

    

    Could you help to read all register setting at the fault state happened when you set GRPPWM = 0? Also it is better to comparing with a right state when GRPPWM = 0. I cannot duplicate the failure at your setting on EVM. TLC59108 can support 1MHz I2C. I am not sure if transitioning too fast is the root cause.
    
			
    

		
		
		
		
	
    
	
    
		
    
			
		
    
	
    

	            
                 	
	
    
				
		                
                
                
                
                
                
                
        		
		
				
    
			
		
    
		
		 
		
		
     
    
	
    

    
			
    
			
    
		
    

		
    
	
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