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http://www.union-ic.com

Rev.02 Jan.2013

1/15

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

Features

MR16 and general lighting

Automotive lighting

Low voltage industrial lighting

LED back lighting

Illuminated signs

Built in thermal and over current shut down.

Internal 30V NDMOS switch

350mA output current

Single pin on/off and dimming control using

DC voltage or PWM at ADJ pin.

Internal PWM filter

Soft-start

High efficiency (up to 95%)

Wide input voltage range: 6V to 30V

40V transient capability

Output shutdown

Up to 1MHz switching frequency

Inherent open-circuit LED protection

Typical 5% output current accuracy

Pin Configurations

Top View

M: Month Code

UM1350

SOT23-5