UM1350 Datasheet, PDF (1/15 Pages) Union Semiconductor, Inc. – 350mA, LED Lighting Driver

UM1350
350mA, LED Lighting Driver
UM1350 SOT23-5
General Description
The UM1350 is capable of driving single or multiple series connected LEDs efficiently from a
voltage source higher than the LED voltage. This step-down converter provides an externally
adjustable output current of up to 350mA from an input supply between 6V and 30V. It can even
reach 8 watts of output power, depending on supply voltage and external components. The
UM1350 consists of an output switch and a high-side output current sensing circuit that uses an
external resistor to set the nominal average output current. Through applying an external control
signal to the ADJ pin, it can adjust the output current to above or below the set value. The ADJ pin
will accept either a DC voltage or a PWM waveform to provide a continuous or a gated output
current. The chip contains a PWM filter which provides a soft-start feature by controlling the rise
of input/output current. It can raise the soft-start by using an external capacitor from the ADJ pin
to ground. Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches
the device into a low current standby state.
The UM1350 is available in a low profile SOT23-5 package.
Applications
z MR16 and general lighting
z Automotive lighting
z Low voltage industrial lighting
z LED back lighting
z Illuminated signs
Features
z Built in thermal and over current shut down.
z Internal 30V NDMOS switch
z 350mA output current
z Single pin on/off and dimming control using
DC voltage or PWM at ADJ pin.
z Internal PWM filter
z Soft-start
z High efficiency (up to 95%)
z Wide input voltage range: 6V to 30V
z 40V transient capability
z Output shutdown
z Up to 1MHz switching frequency
z Inherent open-circuit LED protection
z Typical 5% output current accuracy
Pin Configurations
Top View
M: Month Code
UM1350
SOT23-5
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http://www.union-ic.com Rev.02 Jan.2013
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