NCP5006 ON Semiconductor, NCP5006 Datasheet - Page 15

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

TYPICAL APPLICATIONS CIRCUITS
Standard Feedback
LED, independently of the V
PWM Operation
LED by means of an external PWM signal as depicted in
Figure 29. By optimizing the internal high impedance
presented by the FB pin, one can set up a simple R/C
network to accommodate such a dimming function. Two
modes of operation can be considered:
•
•
function, from a human eye standpoint, it will continuously
The standard feedback provides a constant current to the
The analog feedback Pin 3 provides a way to dim the
Although the pulsed mode will provide a good dimming
Pulsed mode, with no filtering
Averaged mode with filtering capacitor
GND
Figure 28. Basic DC Current Mode Operation with Analog Feedback
bat
supply and number of LED
15 W
GND
R1
V
bat
LWT67C
4
2
3
D6
NCP5006
U1
EN
GND
FB
http://onsemi.com
LWT67C LWT67C LWT67C LWT67C
D5
V
V
NCP5006
bat
out
15
5
1
V
associated in series. Figure 28 depicts a typical application
to supply 13 mA to the load.
D4
start and stop the converter, yielding high transients . These
transients might generate spikes difficult to filter out in the
rest of the application, a situation not recommended. The
output current depends upon the duty cycle of the signal
presented to the node Pin 3: this is very similar to the digital
control discussed in Figure 31.
converter operates continuously, together with a very good
dimming function. The cost is an extra resistor and one
extra capacitor, both being low cost parts.
bat
The average mode yields a noise free operation since the
L1
22 mH
D3
MBR0530
4.7 mF
D1
C1
D2
GND
GND
C2
1.0 mF