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TPS92518: Trimming is necessary for mass production?

KANJI SHIBATANI
Mastermind 6205 points
Part Number: TPS92518

 

Hello

My customer had started design using TPS92518.

We see Eq(5) in datasheet p13.

As per customer's calculation ,even though LED_PKTH_DAC=255, they see +/- 8% including the accuracy of Vcst, tDEL,td_off. ( assume inductor L(uH) =+/- 0%) .

( I don't attach customer's excel calc. sheet, but I believe it should be correct)

Customer want to keep the ILED accuracy within +/- 5%  including inductors and resistors.

 

Q1

Do you have any practical idea for improve error depends Vcst, tDEL, td_off ?

Q2  

Do you think customer should trim the Rsense resistor or change(trim)  LED_PKTH_DAC for mass production?

 

Thank you for your support.

Best Regards

 

 

  • 0
    TI__Mastermind 28655 points
    Hello,

    This requires analyzing where the current regulation errors are in the design. If the inductor current ripple is high the inductor tolerance can be a large contributor. Are they using 1% current sense resistors? They can lower this to 0.1% to remove that variable. This just requires design analysis to remove or at least know where the errors are coming from. You can trim the setpoint via LED_PKTH_DAC. They just have to set the current a little higher so they can trim both ways (+/-).

    Regards,