yb1508p YOBON TECHNOLOGIES,INC., yb1508p Datasheet - Page 4

• Manufacturer Part Number: yb1508p
• Description: Step-up Dc-dc Converter White Driver
• Manufacturer: YOBON TECHNOLOGIES,INC.

Functional Block Diagram
Application Information
Operation
YB1508 MRev1.4
T h e o p e r a t i o n o f Y B 1 5 0 8 c a n b e
understood by referring to the block
d i a g r a m i n F i g u r e 3 .
proportional to the switch current is added
to a ramp output and the resulting sum is
fed into the positive terminal of the PWM
comparator. When this voltage exceeds
the level of the comparator negative input,
the peak current has been reached, and
the SR latch is reset and turns off the
power switch. The voltage at the negative
input of the comparator comes from the
output of the error amplifier. The error
amplifier sets the correct peak current
level to keep the output in regulation. If
the error amplifier’s output increases,
more current is delivered to the output; if it
decreases, less current is delivered.
Inductor Selection
A 22uH inductor is recommended for most
YB1508 applications. Although
Step-up DC-DC Converter , White LED Driver
A v o l t a g e
Figure 3. Block Diagram
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small size and high efficiency are major
concerns, the inductor should have low
core losses at 1MHz and low DCR
(copper wire resistance).
Capacitor Selection
The small size of ceramic capacitors
m a k e s t h e m i d e a l f o r Y B 1 5 0 8
applications. X5R and X7R types are
recommended because they retain their
capacitance over wider voltage and
temperature ranges than other types.
Diode selection
To maintain high efficiency, the average
current rating of the schottky diode
should be larger than the peak inductor
current, IPK. Schottky diode with a low
forward drop and fast switching speeds
are ideal for increasing efficiency in
portable
breakdown voltage of the schottky diode
must be larger than the output voltage.
applications.
The
YB1508
reverse
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