STMicroelectronics EVALHVLED815W10 and EVALHVLED815W15 Evaluation Board for the Offline LED Driver with Primary-Sensing and High Power Fact EVALHVLED815W10 データシート

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Finally the current sense resistor R

SENSE

 can be estimated in order to select the 

desiderated average output current value:

         

where V

 is internally defined (0.2 V typical - see 

).

Starting from the previous estimated components value, further fine-tuning on the real LED 
driver board could be necessary and it can be easily done considering that:

–

Decreasing/increasing the R

PF

 resistor value, the power factor effect 

increases/decreases.

–

Decreasing/increasing the R

OS

 resistor value, the line regulation effect 

increases/decreases.

–

Decreasing/increasing the R

OS

 resistor value, the R

A 

+ R

B

 resistors value should 

be increased/decreased to keep the desiderated voltage across the C

OS

 capacitor 

).

–

Decreasing/increasing the R

SENSE

 resistor value the average output current 

increases/decreases (

A proper printed circuit board layout is essential for correct operation of any switch-mode 
converter and this is true for the HVLED815PF device as well. Careful component placing, 
correct traces routing, appropriate traces widths and compliance with isolation distances are 
the major issues.

In particular:


Current sense resistor (R

SENSE

) should be connected as close as possible to the 

SOURCE pin, maintaining the trace for the GND as short as possible.



Resistor connected on CS pin (R

OS

, R

PF

, R

1

) should be connected as close as 

possible to the pin.



Compensation network (R

COMP

, C

COMP

) should be connected as close as possible to 

the COMP pin, maintaining the trace for the GND as short as possible.



Signal ground should be routed separately from power ground, as well from the sense 
resistor trace.



DMG partition resistors (R

DMG

, R

FB

) should be connected as close as possible to the 

DMG pin, minimizing the equivalent parasitic capacitor on DMG pin.