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
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.
Applications
White LED Backlight Display for PDA
Pocket PC
Smart Phones
Handheld Devices
Cellular Phones
Ordering Information
ORDER
NUMBER
G5121TB1U
G5121TP1U
MARKING
5121x
5121x
TEMP.
RANGE
-40°C ~ +85°C
-40°C ~ +85°C
PACKAGE
(Pb free)
SOT-23-6
TSOT-23-6
Note:TB: SOT23-6 TP: TSOT-23-6
1: Bonding Code
U: Tape & Reel
Pin Configuration
Typical Application Circuit
G5121
L1
V
IN
2.7V to 4.2V
4.7µH
VCC
SW
OVP
D1
SW
1
6
VCC
C1
4.7µF/6.3V
PWM Dimming
Waveform
C2
1µF/25V
5 LEDs
G5121
SHDN
GND
FB
R
S
GND
2
5
OVP
FB
3
SOT-23-6/TSOT-23-6
4
SHDN
C1:TAIYO YUDEN, JMK212BJ475KD
C2:TAIYO YUDEN, TMK316BJ105KD
Ver: 1.3
Nov 13, 2006
TEL: 886-3-5788833
http://www.gmt.com.tw
1
GMT [ GLOBAL MIXED-MODE TECHNOLOGY INC ]
