ILD4071 Datasheet, PDF (19/25 Pages) Infineon Technologies AG – LED Driver for High Power LEDs

ILD4071
Application Information
8
Application Information
Note: The following information is given as a hint for the implementation of the device only and shall not be
regarded as a description or warranty of a certain functionality, condition or quality of the device.
8.1
Output Peak Current Adjustment via R_SET
The external resistor R_SET is used to adjust the peak current of the regulator. Maximum achievable peak current
is 700mA and minimum achievable peak current is 100mA. The SET pin provides an internally fixed voltage level
at typ.: 1.225V. Out of this considerations the equation is:
I_peak = (1.225V / R_SET) * 5710
The factor 5710 is derived from following considerations:
• Ipeak, max = 700mA (R_SET = 10kΩ)
• Ipeak,min = 100mA (R_SET = 70kΩ)
Internal comperator voltage at SET pin = 1.225V.
The circuitry behind the SET pin is adjusting higher peak currents with lower R_SET values.
The R_SET value should be in the range from 10kΩ to 70kΩ to achieve the requested peak current range.
The following setup applies for the table displayed in Figure 9: V_REC=12V, V_LED=7.2V, L_SW=220µH.
I_PEAK [mA]
100
200
300
400
500
600
700
R_SET [kΩ]
70
35
23
18
14
12
10
Figure 9 R_SET Resistor Selection
Datasheet
19
Rev. 1.0, 2011-11-16