ACT6359

Rev 1, 14-Feb-11

- 6 -

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Copyright © 2011 Active-Semi, Inc.

Capacitor Selection

The ACT6359 requires only a tiny 0.47µF output

capacitor for most applications. For circuits driving 6

or fewer LEDs, a 4.7µF input capacitor is generally

suitable. For circuits driving more than 6 LEDs, a

10µF input capacitor may be required.

When choosing a larger inductor which results in

CCM operation, stability and ripple can be improved

by adding a small feed forward capacitor from OUT

to FB. About 3000pF is a good starting point for

most applications, although a larger value can be

used to achieve best results in applications with 6

or fewer LEDs.

Ceramic capacitors are recommended for most ap-

plications. For best performance, use X5R and X7R

type ceramic capacitors, which possess less degra-

dation in capacitance over voltage and temperature.

Diode Selection

The ACT6359 requires a Schottky diode as the rec-

tifier. Select a low forward voltage drop Schottky

the peak current limit (500mA) and a peak repetitive

mum output voltage, typically set by the OV thresh-

old.

Shutdown

The ACT6359 features a low-current shutdown

mode. In shutdown mode, the control circuitry is

disabled and the quiescent supply current drops to

less than 1µA. To disable the IC, simply drive EN to

a logic low. To enable the ICs, drive EN to a logic

high or connect it to the input supply.

Low Input Voltage Applications

In applications that have low input voltage range,

such as those powered from 2-3 AA cells, the

ACT6359 may still be used if there is a suitable sys-

tem supply (such as 3.3V) available to power the

controller. In such an application, the inductor may

be connected directly to the battery, while the IC

power is supplied by the system supply.