NUD4011 データシートの表示（PDF） - ON Semiconductor

部品番号

コンポーネント説明

メーカー

NUD4011

Low Current LED Driver

ON Semiconductor 

NUD4011

APPLICATION INFORMATION

Design Guide for DC Applications

1. Define LED’s current:

a. ILED = 30 mA

2. Calculate Resistor Value for Rext:

a. Rext = Vsense (see Figure 2) / ILED

b. Rext = 0.7(TJ = 25 °C) / 0.030 = 24 W

3. Define Vin:

a. Per example in Figure 5, Vin = 120 Vdc

4. Define VLED @ ILED per LED supplier’s data

sheet: per example in Figure 5,

a. VLED = 3.0 V (30 LEDs in series)

b. VLEDs = 90 V

5. Calculate Vdrop across the NUD4001 device:

a. Vdrop = Vin – Vsense – VLEDs

b. Vdrop = 120 V – 0.7 V – 90 V

c. Vdrop = 29.3 V

6. Calculate Power Dissipation on the NUD4001

device’s driver:

a. PD_driver = Vdrop * Iout

b. PD_driver = 29.3 V 0.030 A

c. PD_driver = 0.879 W

7. Establish Power Dissipation on the NUD4001

device’s control circuit per below formula:

a. PD_control = (Vin – 1.4 – VLEDs)@ / 20,000

b. PD_control = 0.040 W

8. Calculate Total Power Dissipation on the device:

a. PD_total = PD_driver + PD_control

b. PD_total = 0.879 W + 0.040 W = 0.919 W

9. If PD_total > 1.13 W (or derated value per

Figure 3), then select the most appropriate

recourse and repeat steps 1−8:

a. Reduce Vin

b. Reconfigure LED array to reduce Vdrop

c. Reduce Iout by increasing Rext

d. Use external resistors or parallel device’s

configuration

Vin 1

Boost 2

Rext 3

PWM

4

120 V

NUD4011

Current

Set Point

8 Iout

7 Iout

6 Iout

Iout

5

LED1

LED2

LED30

Figure 5. 120 V Application

(Series LED’s Array)

10. Calculate the junction temperature using the

thermal information on Page 8 and refer to

Figure 4 to check the output current drop due to

the calculated junction temperature. If desired,

compensate it by adjusting the value of Rext.

http://onsemi.com

4

Share Link: