PT4301
1x/1.5x Auto-Adjust Charge Pump 4-Channel White LED
Driver with Three Dimming Modes
FEATURES
3V-5.5V input voltage
1x/1.5x auto-adjust charge pump
Set LED current by external resistor
Programming 4-channel LED current up to
20mA with 8 levels through the EN/SET pin
Dimming LED by PWM signal through 3
control terminal
LED fault detection
<3% current mismatch
No inductor
Less than 1uA shutdown current
Built-in soft-start and soft mode decision
GENERAL DESCRIPTION
The PT4301 is a 4-channel 1x/1.5x auto-adjust
charge pump white LED driver with three
dimming modes. Auto-adjust charge pump
achieves high efficiency for Li-Ion battery supply.
The three LED dimming modes enable users to
dim the four LEDs all together or individually.
Only a few external components (two flying
capacitors and two filter capacitors at VIN and
VOUT) are needed, which makes the PT4301
ideally suited for mobile applications.
The current through the LED can be set by an
external resistor. The value of the current can
also be adjusted from 3mA to 20mA in a 3mA
step by the EN/SET pin. The EN/SET pin is a
digital interface which has the functions of both
chip enable and LED current setting. The four
LEDs can be turned on and off individually or in a
group of two to four through the three control
terminals, which can also be used to dim the
LEDs by applying PWM control signals.
Built-in soft-start circuit prevents the inrush
current from the power supply during power on
and
1x/1.5x
mode
change.
The
thermal
shutdown and current limiter prevent the PT4301
from being damaged by a high-level current
through it. A shutdown current of less than 1uA
makes the battery last longer. The PT4301 is
available in 4mm*4mm QFN-16 package.
APPLICATION
Cell phones
Laptop computers and PDAs
Digital cameras
Small LCD displays
Programmable current sink
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