ZXLD1352 datasheet(19/21 Pages) DIODES

Part #	ZXLD1352

Description	30V 350mA LED DRIVER WITH 1000:1 PWM DIMMING AND AEC-Q100

PDF	21 Pages

Scroll/Zoom	100%

Manufacturer	DIODES [Diodes Incorporated]

Direct Link	http://www.diodes.com

Logo

19 / 21 page

ZXLD1352

Document number: DS33469 Rev. 3 - 2

19 of 21

www.diodes.com

December 2010

A Product Line of

Diodes Incorporated

Dimming Output Current Using PWM

When the ADJ pin is driven with a low frequency PWM signal (eg 100Hz), with a high level voltage VADJ and a low level of zero,

the output current will be switched on and off at the PWM frequency, resulting in an average output current IOUTavg proportional

to the PWM duty cycle. (See Figure 2)

Figure 3. Low Frequency PWM Operating Waveforms

The average value of output current in this mode is given by:

The average value of output current is given by:

IOUTavg = 0.1DPWM/RS

for DPWM >0.01

PWM dimming is preferable to DC dimming if optimum LED 'whiteness' is required. It will also provide the widest possible

dimming range (approx. 1000:1) and higher efficiency at the expense of greater output ripple.

VADJ

PWM Voltage

Ton

IOUTavg

Toff

0.1/Rs

IOUTnom

Output Current

ZXLD1352 Datasheet(PDF) 19 Page - Diodes Incorporated