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  Richtek Technology Electronic Components Datasheet  

RT8577A Datasheet

High Voltage 4-CH LED Driver

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®
RT8577A
High Voltage 4-CH LED Driver
General Description
The RT8577A is an 4-CH LED driver capable of delivering
120mA for each channel. The RT8577A is a current mode
boost converter with an adjustable switching frequency
via the RT pin from 200kHz to 2.1MHz and a wide VIN
range from 5.5V to 40V.
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
RT8577A automatically detects and disconnects any
unconnected and/or broken strings during operation from
PWM loop to prevent VOUT 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 (OVP/short/OTP) occurs, a
status signal will be sent to the system to shut down the
IC.
Ordering Information
RT8577A
Package Type
QW : WQFN-20L 5x5 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
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
RT8577AGQW : Product Number
RT8577A
GQW
YMDNN
YMDNN : Date Code
Features
Wide Input Supply Voltage Range : 5.5V to 40V
Adjustable Boost Controller Switching Frequency
from 200kHz to 2.1MHz
Programmable Channel Current
Channel Current Matching : ±1.5%
External Dimming Control
Boost MOSFET Over Current Protection
Automatic LED Open/Short Protection to Avoid
Output Over Voltage
VCC Under Voltage Lockout
Adjustable Over Voltage Protection
Thermal Shutdown Protection
Abnormal Status Indicator for OVP/Short/OTP
Condition
AEC-Q100 Grade 3 Certification
RoHS Compliant and Halogen Free
Applications
Automotive Infotainment
LCD TV, Monitor Display Backlight
LEDDriver Application
General Purpose Constant Current Source
Pin Configurations
(TOP VIEW)
GND 1
GND 2
GND 3
LED3 4
LED4 5
20 19 18 17 16
GND
15 STATUS
14 VCC
13 NC
12 CREG
21 11 DRV
6 7 8 9 10
WQFN-20L 5x5
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
DS8577A-01 December 2015
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1


  Richtek Technology Electronic Components Datasheet  

RT8577A Datasheet

High Voltage 4-CH LED Driver

No Preview Available !

RT8577A
Functional Pin Description
Pin No.
Pin Name
Pin Function
1, 2, 3,
21 (Exposed pad)
4, 5
6
7
8
GND
LED4, LED3
OVP
RISET
RT
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Channel 3 and Channel 4 LED Current Sinks. Leave the pins unconnected if not
used.
Over-Voltage Detection Input. The Boost converter turns off when VOVP goes
higher than 2V.
LED Current Set Pin. A resistor or a current from DAC on this pin programs the
full LED current.
Switching Frequency Set. Connect a resistor between RT and GND to set the
boost converter switching frequency.
9
EN
Enable Control Input. When EN is pulled low, the chip will be shut down.
10
SEN
Current Sense Input. During normal operation, this pin senses the voltage
across the external inductor current sensing resistor for peak current mode
control and also to limit the inductor current during every switching cycle.
11
DRV
Boost Converter Power Switch Gate Output. This pin drives the external power
N-MOSFET device.
12
CREG
Regulator Output for Chip Internal use Only. A 1F capacitor should be placed
on this pin to stabilize the 5V output of the internal regulator.
13, 18
NC
No Internal Connection.
14
VCC
Power Supply of the Chip. For good bypass, a low ESR capacitor close to the
pin is required.
15
STATUS
Status Indicator Output. This pin will be pulled to low if fault happens.
16
VC
PWM Boost Converter Loop Compensation Node.
17
PWM
Dimming Control Input.
19
LED1
Channel 1 LED Current Sink, Leave this pin unconnected if it is not used.
20
LED2
Channel 2 LED Current Sink, Leave this pin unconnected if it is not used.
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS8577A-01 December 2015


Part Number RT8577A
Description High Voltage 4-CH LED Driver
Maker Richtek
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