STMicroelectronics STEVAL-TLL009V1 Camera flash based on the STCF07 STEVAL-TLL009V1 STEVAL-TLL009V1 Fiche De Données

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R

LC

 resistor value can be calculated with the following equations:

R

LC 

= (160 mV - I

LC 

* R

HC

) / I

LC

 and P

RLC 

= R

LC 

* I

LC

2

where P

RLC

 is the dissipated power on the R

LC

 resistor. It is recommended to use a thin 

metal film resistor with a 1% or 5% tolerance.

The NTC resistor for sensing LED temperature and the R

X

 resistor create a voltage divider. 

The output of this divider is compared with the 1.192 V internal voltage reference. When 
voltage on the output of the voltage divider is increased over the reference, the logic 
switches off the power circuit. Voltage divider is possible to supply from the NTC pin, where 
is output of the 1.8 V internal reference.