RT8560 Datasheet, PDF (1/15 Pages) Richtek Technology Corporation – High Voltage 4 Channel LED Driver

RT8560
High Voltage 4 Channel LED Driver
General Description
The RT8560 is a 60V 4-channel LED driver capable of
delivering 30mA to each channel with 15 LEDs (3.6V per
diode) total 60 LEDs with one driver. The RT8560 is a
current mode boost converter opearated at 1MHz switching
frequency, wide V_IN range covers from 7V to 40V and the
on-chip current switch is rated at 1.5A.
The PWM output voltage loop selects and regulates the
LED pin with the highest voltage string to 0.9V allowing
voltage mismatches between LED strings. The RT8560
automatically detects and disconnects any unconnected
and/or broken strings during operation from PWM loop to
prevent V_OUT from over voltage.
The 3% matched LED currents on all channels are simply
programmed with a resistor or a current sink. Both analog
dimming and digitally controlled PWM dimming are
supported by RT8560. Analog dimming is linearly
controlled by an external voltage. With an on-chip output
clampping amplifier and a 200kΩ resistor, PWM dimming
signal is easily low-pass filtered to an analog dimming
signal with one external capacitor for noise-free PWM
dimming. A very high contrast ratio true digital PWM
dimming can be achieved by driving EN pin to PWM
shutdown the chip or by driving ACTL pin.
Other protecting features include programmable PWM
output over voltage protection, LED curren limit, PWM
switch current limit and thermal shutdown. The RT8560
is packaged with a tiny footprint package of WQFN-20L
4x4 packages.
Pin Configurations
(TOP VIEW)
20 19 18 17 16
GND 1
15 LED4
GND 2
14 VC
GND 3
GND
13 SS
SW 4
21
12 OVP
SW 5
11 EN
6 7 8 9 10
WQFN-20L 4x4
DS8560-01 April 2011
Features
z High Voltage : V_IN up to 40V, V_OUT up to 60V, Driving
up to 60 x 3.6V LEDs (15 each channel)
z Channel Current Programmabe 4mA to 30mA and
Matched to 3% Accuracy
z Current Mode PWM 1MHz Boost Converter
z Easy Analog and Digital Dimming Control
z Programmable Soft Start
z Automatic Detecting Unconnected and/or Broken
Channel
z Programmable Over Voltage Protection
z Disconnects LED in Digital Dimming : Providing
High Accuracy Digital Dimming by PWM at ACTL
Pin or EN Pin
z V_IN Under Voltage Lockout
z Over Temperature Protection
z Current Limiting Protection
z Small 20-Lead WQFN Package
z RoHS Compliant and Halogen Free
Applications
z UMPC and Notebook Computer Backlight
z GPS, Portable DVD Backlight
z Desk Lights and Room Lighting
Ordering Information
RT8560
Package Type
QW : WQFN-20L 4x4 (W-Type)
Note :
Lead Plating System
G : Green (Halogen Free and Pb Free)
Richtek products are :
` RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
` Suitable for use in SnPb or Pb-free soldering processes.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
www.richtek.com
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