ZXLD1321 Ver la hoja de datos (PDF) - Zetex => Diodes

Número de pieza

componentes Descripción

Fabricante

ZXLD1321

Boost mode DC-DC converter for LED driving with 1A output and current control

Zetex => Diodes 

ZXLD1321

Fig 1

PWM control

A wider dimming range can be achieved by applying a PWM control signal to the ADJ pin to turn

the device on and off, giving an average output current proportional to the duty cycle of the

control signal. The ADJ pin can be driven directly from the open drain NMOS output of a

microcontroller, or indirectly with a low saturation voltage NPN transistor such as the Zetex

ZXTN25015DFH. (Fig 2).

ZXTN25015DFH

ADJ

ZXLD1321

Fig 2

In the circuit of Fig 4, the average LED output current will be

I LED (avg) = ILED (nom) * D

Where duty cycle

D = T2

(T1+ T 2)

A PWM frequency of 200Hz, or lower is recommended, to minimize errors due to the rise and fall

times of the converter output.

Issue 1 - January 2008

12

© Zetex Semiconductors plc 2008

www.zetex.com

Share Link: