ITech IT8500plus Series User Manual page 47

According to four parameters above and the V-I curve of LED, you can
calculate the value of R and Vd.

R

V
d
Or you can roughly calculate the value of R and Vd with the following equation.
V =V*0.8
d
Where:

V: constant working voltage of load LED of LED constant current source;

I: output current of LED constant current source;

V

R: constant resistance.
In the following example, the output voltage of LED driver is 50V, verify that
whether the output current of LED is rated current 200mA: Vd=50V*0.8=40V
R=(0.2*50V)/0.2A=50Ω.
Setting CR-LED Mode
Example: LED driver specification
The output current is 200mA and the range of output voltage is from 45V to
62V.
Operating steps:
1. Start CR-LED function and set the Vd value.
1) Press [Shift] + [CR] keys to enter configuration menu.
2) Press Right Key and select ON. Press
3) Press the
2. Set CR mode
1) Press [CR] key and set corresponding constant resistance. (Set
2) Press the
3. Press [On/Off] key to turn on load input.

V V
2 1

I I
2 1
 
 
V I R
o 0
NOTE
The value of V2, V1, I2 and I1 should be close to the static working point of LED as
shown in the red circle above.
R=0.2V/I
: break-over voltage of diode (string);
d
(Set Vd=40V).
Select OFF to disenable CR-LED function, and then press [Enter] to
exit the setting menu.
key to save the settings.
[Enter]
CR=50Ω)
key to save the settings.
[Enter]
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Functions and Characteristics
key to set the Vd value.
[Enter]
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