Preliminary
RT9272
High Performance, Constant Current LED Driver for Dual
Panel Mobile Phone
General Description
The RT9272 is a high efficiency step-up DC-DC converter
specifically designed for dual panel mobile phone
applications.
According to SP status, RT9272 can either regulates output
current flowing through series-connected LEDs for main
panel or for sub panel with a common output LC filter. This
along with compact VDFN-10L 3x3 package and high
switching frequency allows less part count and smaller
external components for space and cost saving.
Pulling low EN pin shuts down the chip and reduces the
supply current to less than 1μA. The EN pin also accepts
PWM signal for LED brightness dimming control. The
averaged LED current is well proportional to the duty cycle
of the PWM signal. The internal soft start reduces inrush
current during EN turning on or PWM dimming control.
Other features include OVP, OCP and OTP. OVP prevents
the damages in case of feedback loop open.
Features
Low V
IN
Operating Range : 2.7V to 4.5V
Maximum Output Voltage up to 16V
Small LC filter by 1.1MHz Operation Frequency
Share One Set of Inductor and Schottky Diode for
2 Channels
Programmable Dimming Function by EN Pin with
100Hz to 1kHz
40μA Quiescent Current (Switch-Off)
μ
Internal Soft-Start Function to Avoid PWM Dimming
Noise.
Zero Shut Down Supply Current
Complete Protection : OVP, OCP, OTP and SS
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Dual panel mobile phone, with LED backlight
Pin Configurations
(TOP VIEW)
GND
FB2
CH2
VCC
CH1
1
2
3
4
5
11
10
9
8
7
6
Ordering Information
RT9272
Package Type
QV : VDFN-10L 3x3 (V-Type)
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
LX
SP
OVP
EN
FB1
VDFN-10L 3x3
Note :
Richtek Pb-free and Green 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.
100% matte tin (Sn) plating.
V
IN
Typical Application Circuit
C
IN
2.2uF
L
4.7uF
SS0520
DSH
C
OUT
1uF
Sub-Panel
Main Panel
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.
4
10
VCC
LX
RT9272
Chip Enable
8
OVP
7
EN
5
CH1
9
3
SP
CH2
R1 6
2 R2
FB2
FB1
GND
1
Figure 1. 2LEDs for Sub panel and 3LEDs for Main panel
DS9272-09 August 2007
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
