NCP5006 ON Semiconductor, NCP5006 Datasheet - Page 8

• Manufacturer Part Number: NCP5006
• Description: Compact Backlight LED Boost Driver
• Manufacturer: ON Semiconductor

Output Current Range Set−Up
drop across the sense resistor R1. The voltage drop is
constantly monitored internally, and maximum peak
current allowed in the inductor is set accordingly in order
to keep constant this voltage drop (and thus the current
flowing through the LED). For example, should one need
a 10 mA output current, the sense resistor should be sized
according to the following equation:
The current regulation is achieved by means of an external sense resistor connected in series with the LED string.
The current flowing through the LED creates a voltage
R 1 + Feedback Threshold
I out
Pulse
GND
+ 200 mV
FB
3
10 mA
22 W
GND
R1
+ 20 W
CONTROLLER
Figure 9. Basic Schematic Diagram
Figure 8. Output Current Feedback
LWT67C LWT67C LWT67C LWT67C LWT67C
4
2
3
http://onsemi.com
D6
V
(eq. 9)
bat
NCP5006
U1
EN
GND
FB
NCP5006
8
D5
V
V
22 mH
yields 9.09 mA, good enough to fulfill the back light
demand. The typical application schematic diagram is
provided in Figure 9.
L1
bat
out
A standard 5% tolerance resistor, 22 W SMD device,
GND
5
1
D4
Q1
V
V
out
1
bat
D3
L1
22 mH
MBR0530
D1
4.7 mF
R1
xW
C1
D1
D2
GND
GND
GND
C2
1.0 mF