Datasheet

NCP5005
http://onsemi.com
17
Digital Control
Due to the EN pin, a digitally controlled luminosity can
be implemented by providing a PWM signal to this pin (see
Figure 31). The output current depends upon the Duty
Cycle, but care must be observed as the DC/DC converter
is continuously pulsed ON/OFF and noise are likely to be
generated.
Figure 31. Typical Semi−Pulsed Mode of Operation
EN
1
5
V
out
V
bat
R1
NCP5005
L1
22 mH
V
bat
C1
4.7 mF
GND
U1
4
2
GND
GND
FB
3
D1
MBR0530
22 W
GND
GND
Pulse
C2
1.0 mF
NOTE: Pulse width and frequency depends upon the application constraints.
D6 D5 D4 D3 D2
LWT67C LWT67C LWT67C LWT67C LWT67C
V
load
The PWM operation, using the EN pin as a digital
control, is depicted in Figures 32 and 33. The tests have
been carried out at room temperature with V
bat
= 3.60 V,
L = 22 mH, five LEDs in series, RFB = 22 W.
PWM
VFB
VPWM
V
load
Figure 32. Operation @ PWM = 10 kHz, DC = 10%