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YB1517

Step-up DC-DC Converter & White LED Driver

YOBON TECHNOLOGIES,INC. 

YB1517

Step-up DC-DC Converter & White LED Driver

Inductor Selection

A 22μH inductor is recommended for most

applications to the dc to dc converter and

OLED supply and TFT panel power supply.

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 4.7μF capacitor is sufficient for most

applications. For additional bypassing, a

100nF ceramic capacitor can be used to

shunt high frequency ripple on the input.

The input bypass capacitor CIN, as shown

in Figure 1, must be placed close to the IC.

This will reduce copper trace resistance

which affects input voltage ripple of the IC.

For additional input voltage filtering, a

100nF bypass capacitor can be placed in

parallel with CIN to shunt any high

frequency noise to ground. The output

capacitor, COUT, should also be placed

close to the IC. Any copper trace

connections for the COUT capacitor can

increase the series resistance, which

directly effect output voltage ripple.

The feedback network, resister R2 should

be kept close to the FB pin to minimize

copper trace connections that can inject

noise into the system. The ground

connection for the feedback resistor

network should connect directly to an

analog ground plane. The analog ground

plane should tie directly to the GND pin. If

no analog ground plane is available, the

ground connection for the feedback

network should tie directly to the GND pin.

Trace connections made to the inductor

and Schottky diode should be minimized to

reduce power dissipation and increase

overall efficiency.

Figure 5: Typical Application Circuit

YB1517 Rev.1.4

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