Diodes AP8802H Manuel d'utilisateur télécharger pdf (Page 10)

AP8802H

60V 1A LED STEP-DOWN CONVERTER

AP8802H

Document number: DS32227 Rev. 6 - 2

10 of 14

www.diodes.com

May 2012

PRELIMINARY

NEW PRODUCT

Applications Information (cont.)

Soft-Start

An external capacitor from the CTRL pin to ground will provide a soft-start delay, by increasing the time taken for the voltage on this pin to

rise to the turn-on threshold and by slowing down the rate of rise of the control voltage at the input of the comparator. Adding capacitance

increases this delay by approximately 200µs/nF. The graph below shows the variation of soft-start time for different values of capacitor.

012020 10040 60 80

-S

IME (ms)

CAPACITANCE (nF)

Soft Start Time vs. Capacitance from ADJ Pint to Ground

-2

Thermal Considerations

The graph below in Figure 19, gives details for power derating. This assumes the device to be mounted on a 25x25mm PCB with 1oz

copper standing in still air.

-40 -25 5-10 20 35 50 8065 95 110 125

AMBIENT TEMPERATURE (°C)

Maximum Power Dissipation

Figure. 19 AP880H Derating Curve

DISSI

N (W)

2.5

1.5

0.5

1 2 ... 5 6 7 8 9 10 11 12 13 14

Pas de commentaire

Diodes AP8802H Manuel d'utilisateur Page 10