A customer asks a question about the LT3741: “how (do) you calculate the accuracy or tolerance of the current it is controlling”?
Let’s limit the discussion to the VCTRL = 1.5V case because you will have the best current regulation accuracy when VCTRL = 1.5V.
The LT3741 regulates the voltage across the resistor sensing the current (the SENSE+ to SENSE- voltage) as shown in the image below of the Full Range SENSE+ to SENSE- line item from the LT3741 datasheet ELECTRICAL CHARACTERISTS table:
I asked the design group and they said the Full Range SENSE+ to SENSE- line item is at a fixed duty (12VIN and constant VOUT), so if your application is a fixed duty your current regulation accuracy will be according to Full Range SENSE+ to SENSE- line item shown above.
If your application is NOT a fixed duty, there will be UP TO +/-1% of error IN ADDITION to the Full Range SENSE+ to SENSE current regulation error indicated above, DEPENDING ON YOUR DUTY CYCLE VARIATION. According to the design group, the +/- 1% variation in current regulation accuracy shown by the Current Regulation Accuracy CTRL = 1.5V, VIN = 12V graph from the datasheet TYPICAL PERFORMANCE CHARACTERISTICS shown below is due to a full sweep of duty cycle.
The effect of an increase in current regulation error with duty cycle range is shown in the datasheet VIN vs VOUT series of graphs shown below: