Rev1.0

Preliminary and all contents are subject to change without prior notice

© Seaward Electronics Inc., 2014. • www.seawardinc.com.cn • Page 7

SE2490

2.8A，Wide-Input Sensorless CC/CV Step-Down

DC/DC Converter

capacitance. In the case of ceramic output

contribute to the ripple. Therefore, a lower

capacitance value can be used for ceramic type. In

the case of tantalum or electrolytic capacitors, the

ripple is dominated by RESR multiplied by the

ripple current. In that case, the output capacitor is

chosen to have sufficiently low ESR.

For ceramic output capacitor, typically choose

a capacitance of about 470μF. For tantalum or

electrolytic capacitors, choose a capacitor with less

than 50mΩ ESR.

Rectifier Diode

Use a Schottky diode as the rectifier to

conduct current when the High-Side Power

Switch is off.

The Schottky diode must have current rating

higher than the maximum output current and a

reverse voltage rating higher than the maximum

input voltage.

Output Cable Resistance Compensation

To compensate for resistive voltage drop

across the charger's output cable, the SE2490

integrates a simple, user-programmable cable

voltage drop compensation using the impedance

at the FB pin. Use the curve in Figure 2 to choose

the proper feedback resistance values for cable

voltage divider.

Figure2 Cable Compensation at Various Resistor Divider Values