ACE717C

High Efficiency 1.2MHz 24V Step-up DC/DC Converter

VER 1.1

6

Inductor Selection

The recommended values of inductor are 4.7 to 22μH. Small size and better efficiency are the major

concerns for portable device, such as ACE717C used for mobile phone. The inductor should have low

core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation current rating should

be considered.

Capacitor Selection

voltage filtering, ceramic capacitors with low ESR are recommended. X5R and X7R types are suitable

because of their wider voltage and temperature ranges.

Diode Selection

Schottky diode is a good choice for ACE717C because of its low forward voltage drop and fast reverses

recovery. Using Schottky diode can get better efficiency.

The

high

speed

rectification is also a good

characteristic of Schottky diode for high switching frequency. Current rating of the diode must meet the

root mean square of the peak current and output average current multiplication as following:

The diode’ s reverse breakdown voltage should be larger than the output voltage.

Layout Consideration

When laying out the printed circuit board, the following checking should be used to ensure proper

operation of the ACE717C .

Check the following in your layout:

1.

The power traces, consisting of the GND trace, the SW trace and the VIN, trace should be kept short,

direct and wide.

2.

Does the (+) plates of Cin connect to Vin as closely as possible. This capacitor provides the AC

current to the internal power MOSFETs.

3.

Keep the switching node SW away from the sensitive VOUT node.

4.

Keep the (-) plates of Cin and Cout as close as possible