The LED driver circuit i've made here does not output a constant 1A current.
With an input voltage of 12V and 9V total Vf on the three LEDs (CREE LED star), the current is only 0.65A. Am I understanding the datasheet correctly? If so, the AL8860 should output 1A with a 0.1 ohm resistor across the Vin - SET pins (Iout = 0.1/Rs).
When testing on a power supply, I set the voltage limit to 12V and increase the current from 0. The voltage starts at 7V and increases as the current increases until it hits 12V between 1.1 and 1.2A. The power supply will then switch to voltage limiting and the current will drop to 0.65A, staying at 12V. As I then drop the current limit down, it switches back to current limiting at 0.8A, the voltage then changes from 12V to 8-9V.
I'm sorry for the convoluted explanation of my testing but I cannot understand what is happening here. The PCB and components are all correct.
Note: The MOSFET is not currently in the physical design.