RT8577 Datasheet, PDF (1/12 Pages) Richtek Technology Corporation – High Voltage 4-CH LED Driver

RT8577
High Voltage 4-CH LED Driver
General Description
The RT8577 is an 4-CH LED driver capable of delivering
200mA for each channel. The RT8577 is a current mode
boost converter with an adjustable switching frequency
via the RT pin from 100kHz to 1MHz and a wide VIN
range from 9V to 28V.
The PWM output voltage loop selects and regulates the
LED pin with the highest voltage string to 0.6V, hence
allowing voltage mismatches between LED strings. The
RT8577 automatically detects and disconnects any
unconnected and/or broken strings during operation from
PWM loop to prevent V_OUT from over voltage. The 1.5%
matched LED currents on all channels are simply
programmed with a resistor. A very high contrast ratio true
digital PWM dimming can be achieved by driving the PWM
pin with a PWM signal.
When an abnormal situation (open/short/thermal) occurs,
a status signal will be sent to the system to shut down
the IC.
Ordering Information
RT8577
Package Type
QW : WQFN-20L 5x5 (W-Type)
Note :
Lead Plating System
Z : ECO (Ecological Element with
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
RT8577
ZQW
YMDNN
RT8577ZQW : Product Number
YMDNN : Date Code
Features
z Wide Input Supply Voltage Range : 9V to 28V
z Adjustable Boost Controller Switching Frequency
from 100kHz to 1MHz
z Programmable Channel Current
z Channel Current Matching : ±1.5%
z External Dimming Control
z Boost MOSFET Over Current Protection
z Automatic LED Open/Short Protection to Avoid
Output Over Voltage
z VCC Under Voltage Lockout
z Adjustable Over Voltage Protection
z Under Voltage Protection
z Thermal Shutdown Protection
z Abnormal Status Indicator for Open/Short/Thermal
Condition
z RoHS Compliant and Halogen Free
Applications
z LCD TV, Monitor Display Backlight
z LEDDriver Application
z General Purpose Constant Current Source
Pin Configurations
(TOP VIEW)
20 19 18 17 16
LED2 1
LED1 2
GND 3
OVP/UVP 4
RISET 5
GND
15 CREG
14 DRV
13 PGND
12 SEN
21 ¹¹ EN
6 7 8 9 10
WQFN-20L 5x5
DS8577-00 November 2011
www.richtek.com
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