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LED Driver System Calculation

This document provides calculations and specifications for an LED driver circuit using the FL7701 controller including: - Input values for maximum voltage, LED forward voltage, number of LEDs, peak and RMS LED currents, efficiency, and switching frequency. - Calculated values for current ripple, minimum LED current, average peak current, minimum duty cycle, output voltage, inductance, resistor values, expected output and input power. - Graphs showing the LED peak current, minimum current, input voltage, duty cycle, and expected waveforms over time.

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Tibor Rózsa
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440 views23 pages

LED Driver System Calculation

This document provides calculations and specifications for an LED driver circuit using the FL7701 controller including: - Input values for maximum voltage, LED forward voltage, number of LEDs, peak and RMS LED currents, efficiency, and switching frequency. - Calculated values for current ripple, minimum LED current, average peak current, minimum duty cycle, output voltage, inductance, resistor values, expected output and input power. - Graphs showing the LED peak current, minimum current, input voltage, duty cycle, and expected waveforms over time.

Uploaded by

Tibor Rózsa
Copyright
© Attribution Non-Commercial (BY-NC)
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as XLS, PDF, TXT or read online on Scribd
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Iout Number Vin_bulk Duty_ref Imin_ref f[kH] time Duty Ipeak Vin Imin Current ripple(I) Duty_min Delt Io I

FL7701 SYSTEM Calculation(Method2)


Item
Maximun Input Voltage LED Forward Voltage Number of LED LED Peak Current LED rms current Efficency Switching Frequency Vin.max.ac= Vf= Number of LED= ILED.peak= Ivae_rms= Eff= fsw=

Value
220 3.5 10 500

Units
[V] [V] [EA] [mA] 300 [mA] 85 [%] 45 [kHz]

Be inserted Input items

Current ripple LED min. Current LED current ave_pk Minimum Duty Output Voltage

I= Imin= (Imax+Imin)/2= Dmin= Vo= Lm= Rcs= Rt= Pout= Pin=

151.5 348.53

[mA] [mA]

Results

424 [mA] 13.237 [%] 35.000 4.455 1.000 44.919 10.500 12.353 [V] [mH] [ ] [k ] [W] [W]

Results

Inductance Current Sensing Resistor Frequency Setting Resistor Expected output power Expected Input power

max(Ipeak) 0.5 ripple(I) 151.472

0.6 [A] 0.5 0.4 0.3

Ipea k

LED min. current 348.5

0.2
0.1 0

-0.1 0
[A]
400

10

15 [ms]

Input 300 200 100


0

[ms]
0 5 10 15

-100

-100 -200 -300 -400

10

15

condition: Imax > 1.414*Irms

60
Ipea

50 40 30 20 10 0
[ms]

[%]

Duty

10

15

[ms]

Input

[ms]

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