ACE738D

2A, 24V Synchronous Step-Down Converter

VER 1.1

9

Inductor

The inductor is used to supply constant current to the output load, and the value determines the ripple

current which affect the efficiency and the output voltage ripple. The ripple current is typically allowed to

be 30% of the maximum switch current limit, thus the inductance value can be calculated by:

frequency, and

△IL is the

peak-to-peak inductor ripple current.

External Boost rap Capacitor

A boost rap capacitor is required to supply voltage to the top switch driver. A 0.1uF low ESR ceramic

capacitor is recommended to connected to the BST pin and SW pin.

External Soft-start Capacitor

A soft-start capacitor is required to set the soft-start period，which controls the rate of the output voltage

rise. Take the startup current and voltage rise rate into consideration, a 0.1uF ceramic capacitor is

recommended.

PCB Layout Note

For minimum noise problem and best operating performance, the PCB is preferred to following the

guidelines as reference.

1.

Place the input decoupling capacitor as close to ACE738D (VIN pin and PGND) as possible to

eliminate noise at the input pin.

The loop area formed by input capacitor and GND must be minimized.

2.

Put the feedback trace as far away from the inductor and noisy power traces as possible.

3.

The ground plane on the PCB should be as large as possible for better heat dissipation.