Question
We’re working with the WLD in constant current mode, and we think we observe a non linearity between VSET and ILD. Is the non-linearity normal? Should we use external feedback between IMON and VSET?
We chose RSENSE = 0.35 Ω to get 2 A, trim RLIM not to exceed 2 A, and we adjust R between pins 5 and 6 to get 1 A output with VSET = 1 V.
Answer
First, we advise against adding a feedback loop between IMON and VSET because the controller implements internal circuitry to perform that feedback function.
There is a small offset between VSET and ILD to ensure that when VSET is zero the leakage current is minimal. The offset may vary slightly from unit to unit due to internal circuit tolerance variations. Again, it is an offset, but it is not a non-linearity.