Kingbor Technology Co.,Ltd
TEL:(86)0755-26508846 FAX:(86)0755-26509052
KB4317
High Efficiency, Constant Current
2 Watt Boost White-LED Driver
FEATURES
•Operating Voltage:2.3V~6.5V
•High Operating Frequency: 1.2MHz
•High Efficiency: Up to 90%
•High Output Voltage: Up to 32V
•High Output Power: 2W
•Shutdown Current <1 A
•30V Output Over-voltage protection (min)
•Digital Dimming Control.
•Built-in Cycle-by Cycle Current-limiting.
•Built-in Soft-Start Function.
•0.25V Low Reference Voltage(+/-5%)
•Tiny SOT23-6 Package
DESCRIPTION
The KB4317 step-up converter drives white LEDs
with a constant current to provide backlight in cell
phones, PDAs, and other hand-held devices. It
features allowing series connection of the white
LEDs so that the LED currents are identical for
uniform brightness. An enable input can be pulsed
repeatedly to adjust LED’s brightness. The fast 1.2
MHz current-mode PWM control allows for smaller
capacitor and inductor. Fault condition protection
uses cycle-by-cycle current limiting to sense
maximum inductor current, thermal protection and
over-voltage protection. Also included soft-start
eliminates inrush current during start-up. The 0.25V
low reference voltage minimized the power loss
across the current-setting resistor.
The KB4317 is available in SOT23-6 packages
APPLICATIONS
• LED Module
• LED Backlight for LCD Display Vcc>3.6V(7
”
~8
”
)
• Constant Current Source
SIMPLIFIED BLOC DIAGRAM
VIN
LX
ON/OFF
Control
Logic / PWM
Dimming
Control
VREF(250mV)
+
Control Logic
FB
OVP
22V(300uA)
VBG
+
-
Overvoltage
Protection
-
Current Limit
0.75A
+
-
CTL
N
VREF
0.25V
VBG
1.23V
Soft-Start
EN
CTL
GND
REV: 1.0
1
KINGBOR [ KINGBOR TECHNOLOGY CO ]
