TPS60231 Datasheet, PDF (1/16 Pages) Texas Instruments – WHITE LED CHARGE PUMP CURRENT SOURCE WITH PWM BRIGHTNESS CONTROL

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WHITE LED CHARGE PUMP CURRENT SOURCE
WITH PWM BRIGHTNESS CONTROL
TPS60231
SLVS544 – OCTOBER 2004
FEATURES
• Regulated Output Current With 0.4%
Matching
• Drives up to 3 LEDs at 25 mA Each
• LED Brightness Control Through PWM
Control Signal
• High Efficiency by Fractional Conversion
With 1x and 1.5x Modes
• 1 MHz Switching Frequency
• 2.7 V to 6.5 V Operating Input Voltage Range
• Internal Softstart Limits Inrush Current
• Low Input Ripple and Low EMI
• Overcurrent and Overtemperature Protected
• Undervoltage Lockout With Hysteresis
• Ultra-Small 3mm x 3mm QFN Package
APPLICATIONS
• White LED Backlight for Color Displays in
Cellular Phones, Smart Phones, PDAs,
Handheld PCs, Digital Cameras, and
Camcorders
• Keypad Backlight
DESCRIPTION
The TPS60231 charge pump is optimized for white
LED supplies in color display backlight applications.
The device provides a constant current for each LED,
which the initial value can be set by an external
resistor. The supply voltage ranges from 2.7 V to
6.5 V and is ideally suited for all applications powered
by a single LI-Ion battery cell or three to four NiCd,
NiMH, or alkaline battery cells. Over an input voltage
range from 3.1 V to 6.5 V, the device provides a high
output current of up to 25 mA per LED with a total of
75 mA. High efficiency is achieved by utilizing a
1x/1.5x fractional conversion technique in combi-
nation with very low dropout current sources. In
addition, the current controlled charge pump ensures
low input current ripple and EMI. Only two external
1 µF and two 0.47 µF capacitors are required to build
a complete small and low cost power supply solution.
To reduce board space to a minimum, the device
switches at 1 MHz operating frequency and is avail-
able in a small 16-pin QFN (RGT) package.
VIN = 2.7 V
to 6.5 V
1 mF
0.47 mF
0.47 mF
VIN
C1+
C1−
C2+
C2−
EN1
EN2
GND
VOUT
D1
D2
D3
ISET
PGND
1 mF
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004, Texas Instruments Incorporated