LED driver current setting

[eem2am]

Hello, i cannot work out how to set the LED string current in the MAX16812

**broken link removed**

There are two current sense points.
One is the Switching Mosfet current which is done via the SRC pin and this is simply and well explained at the middle left of page 12.

However, the setting of the LED string current is done via the current sense resistor between the CS+ and CS- pins.

-They have attempted to explain how to calculate the sense resistor size at the top left of page 11 but i cannot see how they do it.

Does any reader have any ideas.

 

[exnol]

SRC is the pin through which the switching MOSFET is connected to GND. The MOSFET is turned off when the voltage across the resistor b/n RSRC and GND reaches 600mV. (Hope this will be of use to someone).

 

[alexan_e]

You will fing better explenation in **broken link removed**

in page 3 right side

Peak Inductor Current-Limit Setting
The parallel combination of current-sense resistors R10 and R11 (Rsrc) sets the EV kit’s peak inductor current limit to 2A. Use the following equation to calculate the peak current limit:



where IILIM is the inductor peak current and RTOTAL is the total parallel resistance placed at the R10 and R11 (Rsrc) PCB pads.
Refer to the Internal Switching MOSFET Current Limit section in MAX16812 IC data sheet
for additional information on setting the peak current-limit threshold.

Setting External LEDs Current
Resistors R13 and R14 (Rcs) set the MAX16812 EV kit average LED current up to a maximum 360mA.
The potentiometer R2 allows the external LED current to be adjusted from 175mA (min) to 360mA (max).
The LED string current can be programmed using the following equation:



where ILED is the LED current, VREFI is the voltage at TP1, and 0.82Ω is the parallel resistance of R13 and R14 (Rcs).

Alex