UM1661_16 Datasheet, PDF (1/8 Pages) Union Semiconductor, Inc. – High Efficiency Low Noise PFM Step-Up DC/DC Converter

UM1661
High Efficiency Low Noise PFM Step-Up DC/DC Converter
UM1661 SOT23-6
General Description
The UM1661 PFM step-up DC/DC 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 LEDs brightness. The fast 500kHz to 2MHz
operation frequency allows for smaller capacitor and inductor. Fault condition protection uses
cycle-by-cycle current limiting to sense maximum inductor current and over-voltage protection.
The 0.2V low reference voltage minimizes the power loss across the current sense resistor.
The converter can operate from 2V to 6V, and capable of delivering maximum 200mA output
current at 4-LEDs application with 3V input voltage. Quiescent current drawn from power source
is as low as 120uA. All of these features make UM1661 be suitable for the portable devices,
which are supplied by a single battery.
Applications
Features
 Compact Back Light Module
 Power Source for LED
 Constant Current Source
 Up to 24V Output Voltage
 Wide Operation Range: 2V to 6V
 Maximum 2MHz Operating Frequency
 PWM Dimming Control
 Shutdown Current <1μA
 Current Limit Cycle-by-Cycle
 Low Current Sense Threshold: 200mV
 24V Over Output Voltage Protection
 Compact SOT23-6 Package
Pin Configurations
Top View
Ordering Information
Part Number
UM1661
Packaging Type
SOT23-6
WW: Week Code
UM1661
SOT23-6
Marking Code
LE9
Shipping Qty
3000pcs/7Inch
Tape & Reel
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http://www.union-ic.com Rev.05 May.2016
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