LED Driver. RT4501 Datasheet

RT4501 Driver. Datasheet pdf. Equivalent

RT4501 Datasheet
Recommendation RT4501 Datasheet
Part RT4501
Description High Efficiency Backlight LED Driver
Feature RT4501; ® RT4501/A High Efficiency Backlight LED Driver General Description The RT4501/A is a high-efficie.
Manufacture Richtek Technology
Datasheet
Download RT4501 Datasheet




Richtek Technology RT4501
®
RT4501/A
High Efficiency Backlight LED Driver
General Description
The RT4501/A is a high-efficiency LED driver for backlight
applications. An asynchronous boost converter with an
internal Schottky diode and a current source driver are
designed to support 6LED/channel with wide input voltage
range from 2.5V to 5.5V.
An I2C interface can provide easy backlight control in fast
and high speed mode. The RT4501 supports linear
mappings with 256 steps to setup the brightness of
backlight LEDs. It also supports PWM dimming to adjust
the brightness.
For brightness dimming, the RT4501A supports 128 steps
pulse dimming which determines the LED current, and
RT4501 support 256 steps PWM dimming which
determines the LED current.
The RT4501/A provides complete protection functions such
as input under-voltage lockout, over-current, output over-
voltage and over-temperature protection. The OVP
threshold voltage can be set at 16V and 25.5V for different
applications. The RT4501/A is available in the
WL-CSP-10B 0.87x2.07 (BSC) package.
Features
Input Voltage Range : 2.5V to 5.5V
Internal Schottky Diode
Fast-speed mode I2C Compatible Interface
Drive Up to 7 WLEDs in 2 String
External PWM/Pulse Brightness Control
550k/1.1MHz Switching Frequency
Built-in Internal Soft-Start
PWM Dimming/Pulse Dimming Resolution 256/128
Steps
I2C Programmable 256 Steps Linear Current
Regulation
Up to 85% Efficiency with Small Magnetics
Programmable 16V/25.5V OVP
Current Accuracy ±5% and Current Balance ±3%
UVLO, OVP, OCP, OTP Protection
Shutdown Current : < 1μA
Temperature Range : 40°C to 85°C
RoHS Compliant and Halogen Free
Applications
Cellular Phones
Digital Cameras
PDAs and Smart Phones
Portable Instruments
Simplified Application Circuit
L
VIN
CIN
Enable
RT4501/A
LX VOUT
VIN
EN
PWM
SCL
SDA
GND
FB1
FB2
COUT
VOUT
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS4501/A-00 September 2014
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
1



Richtek Technology RT4501
RT4501/A
Ordering Information
RT4501/A
Package Type
WSC : WL-CSP-10B 0.87x2.07 (BSC)
RT4501 : PWM Dimming
RT4501A : Pulse Dimming
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.
Pin Configurations
(TOP VIEW)
LX A1 A2 GND
VOUT B1 B2 VIN
PWM C1 C2 EN
SDA D1 D2 SCL
FB2 E1 E2 FB1
WL-CSP-10B 0.87x2.07(BSC)
Marking Information
RT4501WSC
1TW
1T : Product Code
W : Date Code
RT4501AWSC
28 : Product Code
28W
W : Date Code
Functional Pin Description
Pin No.
Pin Name
Pin Function
A1
LX
Switch Node of Boost Converter. Connect an inductor between LX and
VIN.
A2
GND
Ground.
B1
VOUT
Power Output of the Asynchronous Boost Converter for Backlight LEDs.
Connect a 1F or larger ceramic capacitor from VOUT to ground.
B2
VIN
Power Input. Connect this pin to the input power supply voltage.
Connect a 10F or larger ceramic capacitor from the VIN to ground.
C1
PWM
PWM Dimming Input for Backlight LED.
C2
EN
Enable Control Input (Active High). The chip is in shutdown mode when
the EN pin is low.
D1
SDA
I2C Serial Data Input/Output. An external pull-up resistor is required.
D2 SCL I2C Serial Clock Input. An external pull-up resistor is required.
E1 FB2 Single Output 2 for Backlight LED.
E2 FB1 Single Output 1 for Backlight LED.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
is a registered trademark of Richtek Technology Corporation.
DS4501/A-00 September 2014



Richtek Technology RT4501
Function Block Diagram
VIN
FB1 FB2
LX
PWM
SCL
SDA
EN
PWM2DC
Digital
Control
VREF
Current
Source Gen.
VFB
EA +
-
VSLOPE
LEDs
OTP
PWM
Logic
OCP
OVP
RT4501/A
VOUT
GND
Operation Description
The RT4501/A is a high efficiency solution with 14 WLEDs
in 2 parallels 7 series for backlight applications. The
RT4501/A optimizes the feedback regulation voltage to
provide up to 85% high efficiency with as high as 8bits
resolution application.
Linear Brightness Dimming
The RT4501/A is built-in a I2C 8-bit resolution brightness
control with maximum 20mA/30mA selection.
Reg0x02<3> corresponds to full-scale LED current control.
Reg0x04 sets 8bits resolution brightness dimming.
PWM Brightness Dimming
Besides programmable built-in I2C backlight LED current
control, the RT4501 features a built-in PWM dimming
current control by setting Reg0x02<6> to 1, offering a
linear current dimming by external clock source. In order
to guarantee the PWM dimming resolution, recommending
dimming frequency have to be operated at range of 400Hz
to 20kHz.
Pulse Brightness Dimming
The EN pin features a simple digital interface to allow
digital brightness control. Using the one-wire dimming
brightness control can achieve as high as 128 steps
resolution, recommending dimming pulse is larger than
0.2μs. RT4501/A keeps shunt down status, when EN pin
is pulled low keeping 1ms.
Copyright ©2014 Richtek Technology Corporation. All rights reserved.
DS4501/A-00 September 2014
OCP Protection
The RT4501/A features a 1A current limitation. Once
detecting current level over current limitation, the
RT4501/A's LX witching will be forced off to avoid large
current damage.
OTP Protection
The over-temperature protection function will be latched
at shutdown status when the junction temperature
exceeds 150°C for 2ms. After re-power on sequence, the
converter will automatically resume switching.
OVP Protection
The over-voltage protection function monitors the output
voltage via the VOUT pin voltage. The OVP threshold
voltage is 25.5V/16V by selection Reg0x02<7>, Once the
LED is open, the output voltage will be limited at OVP
protection level to avoid device breakdown. RT4501 is
shunt-down latched, by triggering OVP event over 40 times.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
3







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