G5121_06 Datasheet, PDF (1/10 Pages) Global Mixed-mode Technology Inc – Fixed Frequency White LED Step-Up Converter

Global Mixed-mode Technology Inc.
G5121
Fixed Frequency White LED Step-Up Converter
Features
„ Inherently Matched LED Current
„ High Efficiency: 87%
„ Drives Up to Five LEDs from 2.5V Supply
„ 24V Internal Power Switch
„ Fast 1MHz Switching Frequency
„ Uses Tiny 1mm Tall Inductors
„ Requires Only 1µF Output Capacitors
„ 19.5V Over Voltage Protection
„ SOT-23-6 and TSOT-23-6 Package
Applications
„ White LED Backlight Display for PDA
„ Pocket PC
„ Smart Phones
„ Handheld Devices
„ Cellular Phones
General Description
The G5121 is a step-up DC/DC converter specifically
designed to drive up to 5 series white LEDs with con-
stant current. Series connection of the LEDs provides
identical LED currents resulting in uniform brightness
and eliminates the need for ballast resistors. The
G5121 switches at 1MHz, allowing the use of tiny ex-
ternal components. A low 0.254V feedback voltage
minimizes power loss in the current setting resistor for
high efficiency. The OVP pin monitors the output volt-
age and turns off the converter whenever the LEDs are
open.
The G5121 is available in low profile SOT-23-6 and
TSOT-23-6 package.
Ordering Information
ORDER
NUMBER
MARKING
TEMP.
RANGE
PACKAGE
(Pb free)
G5121TB1U
5121x -40°C ~ +85°C SOT-23-6
G5121TP1U
5121x -40°C ~ +85°C TSOT-23-6
Note:TB: SOT23-6 TP: TSOT-23-6
1: Bonding Code
U: Tape & Reel
Pin Configuration
Typical Application Circuit
SW 1
G5121
6 VCC
GND 2
5 OVP
FB 3
4 SHDN
SOT-23-6/TSOT-23-6
V_IN
2.7V to 4.2V
C1
4.7µF/6.3V
PWM Dimming
Waveform
L1
D1
4.7µH
VCC
SW
OVP
G5121
SHDN
FB
GND
C2
1µF/25V
5 LEDs
RS
C1:TAIYO YUDEN, JMK212BJ475KD
C2:TAIYO YUDEN, TMK316BJ105KD
Ver: 1.3
Nov 13, 2006
TEL: [phone]
http://www.gmt.com.tw
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