TPS92518: 0.1% duty on PWM dimming

Part Number:TPS92518

Hello

We see data sheet page1 is 0.01%(10,000:1) for PWM dimming range.

So, Customer is evaluating TPS92518 EVM.

Customer applies PWM signal from their MCU to TPS92518EVM.

Customer's issue is ILED =0 mA at PWM=0.1% duty. ..test result is excel file.

Customer is using CREE's 36V/1A LED. (VIN=48V)

Anyway,

I had tested TPS92518EVM myself using PWM signal in LEDSPIMCUEVM and GUI, using same CREE's LED,VIN=48V.

I had also found that ILED is approx 0mA at PWM=0.1% duty.

My test result is attached PPT.

Customer's and my test result about ILED was approx 0mA when duty = 0.1% ... but would you please advise about the reason?

We want to know whether our usage ( register setting ) was wrong or no.

We see TPS92518 EVM user's guide (sluubm0) Fig4 shows Output current 5mA~10mA even duty=0%.

We want to know how to add Offset as Fig4 of user's guide.

( I heard from you that Fig4 is based on PWM dimming only ( not shuntFET dimming) , but how do you achieve Fig4 ?)

We think the corrective aciton should be customer's MCU set higher duty in case small duty ,intentionally.

But concern is linearity curve ( gain/offset) may be changed each VLED ( Customer will use several kind of VLED in their same PCB).

Do you think linearity curve ( gain/offset) may be changed by VLED ?

( I should ask customer to use 0x0Ah~ 0x0Fh for VLED reading?...)

Thank you for your support!

Thank you for your cooperation

Best Regards

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