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YB1520 View Datasheet(PDF) - YOBON TECHNOLOGIES,INC.

Part Name
Description
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YB1520
YOBON
YOBON TECHNOLOGIES,INC. YOBON
YB1520 Datasheet PDF : 10 Pages
1 2 3 4 5 6 7 8 9 10
YB1520
Step-up DC-DC Converter, White LED Driver
be reduced by pulse width modulating the
CTRL. A better approach is to adjust the
feedback voltage for dimming control.
Either a DC level signal or a filtered PWM
signal can be used to control the LED
current as illustrated in Figure 4 and Figure
5 respectively. Using the above different
scheme, the LED current can be controlled
from 20% to 80% to its maximum value.
Figure 4: Dimming Control Using a DC Voltage
Figure 5: Dimming Control Using a Filtered PWM
Signal (1KHz, 2Vp-p, duty 20%~80%)
Over Voltage Protection
The YB1520 has an internal over voltage
protection circuit which also acts as an
open-circuit protection. In the cases of
open circuit or the LEDs failure, the LEDs
are disconnected from the circuit, and the
feedback voltage will be zero. The YB1520
will then switch to a high duty cycle
resulting in a high output voltage, which
may cause SW pin voltage to exceed its
maximum 32V rating. The YB1520 will
shutdown automatically until input condition
changes to bring it out of the shutdown
mode.
Inductor Selection
A 33uH inductor is recommended for most
applications to drive 3X6 WLEDs in
serials/parallel. Although small size and
high efficiency are major concerns, the
inductor should have low core losses at
1MHz and low DCR (copper wire
resistance).
Diode Selection
To maintain high efficiency, the average
current rating of the Schottky diode should
be large than the peak inductor current, IPK.
Schottky diode with a low forward drop and
fast switching speeds are ideal for increase
efficiency in portable application. Choose a
reverse breakdown of the Schottky diode
large than the output voltage.
Capacitor Selection
Choose low ESR capacitors for the output
to minimize output voltage ripple. Multilayer
capacitors are a good choice for this as well.
A 47uF capacitor is sufficient for most
applications.
YB1520 Rev.1.4
www.yobon.com.tw
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