High Performance, Constant Current LED Driver
for Dual Panel Mobile Phone
The RT9272 is a high efficiency step-up DC-DC converter
specifically designed for dual panel mobile phone
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.
QV : VDFN-10L 3x3 (V-Type)
Operating Temperature Range
P : Pb Free with Commercial Standard
RichTek Pb-free 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.
For marking information, contact our sales representative
directly or through a RichTek distributor located in your
area, otherwise visit our website for detail.
z Low VIN Operating Range : 2.7V to 4.5V
z Maximum Output Voltage up to 16V
z Small LC filter by 1.1MHz Operation Frequency
z Share One Set of Inductor and Schottky Diode for
z Programmable Dimming Function by EN Pin with
100Hz to 1kHz
z 40μA Quiescent Current (Switch-Off)
z Internal Soft-Start Function to Avoid PWM Dimming
z Zero Shut Down Supply Current
z Complete Protection : OVP, OCP, OTP and SS
z RoHS Compliant and 100% Lead (Pb)-Free
z Dual panel mobile phone, with LED backlight
Typical Application Circuit
R1 6 FB1
FB2 2 R2
Figure 1. 2LEDs for Sub panel and 3LEDs for Main panel
DS9272-06 November 2005