MCP1643
1 MHz Low Start-up Voltage Synchronous Boost
LED Constant Current Regulator
Features Description 1.6A Typical Peak Input Current Limit Up to 550 mA LED Load Current Low Start-up Voltage: 0.65V (typical, 25 mA LED
Current) Low Operating Input Voltage: down to 0.5V Maximum Input Voltage < VLED < 5.0V Maximum Output Voltage:
-5.0V
-Overvoltage Protection Low Reference Voltage:
-VFB = 120 mV
-Minimal Power Loss on Sense Resistor Pulse-Width Modulation Mode Operation (1 MHz) Internal Synchronous Rectifier Internal Compensation Inrush Current Limiting Internal Soft-Start (240 Вµs typical) Shutdown (EN = GND):
-True Load Disconnect
-Dimming Control by Variable Duty Cycle Shutdown Current: 1.2 ВµA (typical) Overtemperature protection Packages:
-MSOP-8
-2x3 DFN-8 MCP1643 is a compact, high-efficiency, fixed
frequency, synchronous step-up converter optimized to
drive one LED with constant current, that operates from
one and two-cell alkaline and NiMH/NiCd batteries.
The device can also drive two red/green/yellow series
connection LEDs. Applications One and Two Cell Alkaline and NiMH/NiCd
Portable LED Lighting Products LED Flashlight and Head Lamps Rechargeable Flashlights Wall LED Lamps with Motion Detectors LED supply for backlights General LED constant current applications Low-voltage technology allows the regulator to start up
without high-output voltage and load-current overshoot
from a low 0.65V input. High efficiency is accomplished
by integrating the low resistance N-Channel Boost
switch and synchronous P-Channel switch. All …
