Product category:
Power Supply ICs and Controllers
News Release from: Zetex | Subject: ZXLD1100 and ZXLD1101
Edited by the Electronicstalk Editorial
Team on 10 November 2003
LED drivers provide true analogue
dimming control
A new range of white LED drivers feature the novel option of an integrated true analogue dimming mode, offering a noise-free alternative to pulsed dimming control.
A new range of white LED drivers feature the novel option of an integrated true analogue dimming mode, offering a noise-free alternative to pulsed dimming control The ZXLD1100 and ZXLD1101 inductive boost converters can produce an adjustable linear output current for controlling the brightness of series connected LEDs used in colour LCD backlighting
This article was originally published on Electronicstalk on 24 Jul 2008 at 8.00am (UK)
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With a PWM signal of greater than 10kHz applied to its internally filtered enable pin, the ZXLD1100 series IC produces an output current that is linearly proportional to the duty cycle of the enable pin signal.
A signal of less than 1kHz gates the device on and off to produce a conventional chopped output and an average LED current proportional to the enable signal duty cycle.
Where a circuit requires the enable pin to remain available for use, the ZXLD1100 series also offers three alternative dimming control schemes, whereby a DC voltage, PWM or logic signal can be used to trigger the feedback pin.
In its low profile 6-pin SC70 package, the ZXLD1100 helps to reduce PCB size by providing integrated open circuit protection, that removes the need for the external zener and resistor components required by alternative LED driver ICs and the SOT23-5 packaged ZXLD1101.
Both white LED drivers also include an internal NDMOS switch and a peak current sense resistor and can operate to a maximum output voltage of 28V.
Quiescent current is typically 60uA and to help conserve portable battery life, a shutdown function is provided to reduce this current to less than 500nA in the off state.
85% efficient, the ZXLD1100 and ZXLD1101 operate over a wide input voltage range from 2.5 to 5.5V and provide an adjustable output current of up to 50mA.
The ICs drive up to eight series connected LEDs from a Li-ion cell and support colour LCD backlighting in a range of portable products including mobile phones and digital stills cameras.
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