The resistor RSETI sets the current through each LED string (ILED), according to the formula ILED = 1500/RSETI. If RSETI is shorted, the LED current will increase rapidly (the brightness of the backlight/LEDs will increase). The peak inductor current is sensed from the voltage across the current-sense resistor RCS and the RSCOMP resistor as shown in Figure 7 of the datasheet, included below. The voltage across the current sense resistor will cause the switch to be turned when the voltage at CS is 416mV typical which is when the peak current limit is reached.