MP2483 – 2.5A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER

MP2483 Rev. 1.0

www.MonolithicPower.com

4

12/25/2013

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PIN FUNCTIONS

QFN3 x 3

Pin #

SOIC14

Name

Description

1

2

VDD

Supply Voltage. The MP2483 operates from a +4.5V to +55V unregulated

input (with respect to VSS). C1 is needed to prevent large voltage spikes

from appearing at the input.

2

3

VSS

Power Return Pin. Connect to the lowest potential in the circuit, which is

typically the anode of the Schottky rectifier. This pin is the voltage reference

for the regulated output voltage. For this reason care must be taken in its

layout. This node should be placed outside of the D1 to C1 ground path to

prevent switching current spikes from inducing voltage noise into the part.

The exposed pad is also connected to this pin.

3

4

OVP

Over Voltage Protection Pin. Use a voltage divider to program OVP

threshold. When the OVP pin voltage reaches the shutdown threshold 1.2V,

the switch will be turned off and will recover when OVP voltage decreases

sufficiently. When the OVP pin voltage (with respect to VSS) is lower than

0.4V and FB pin voltage is lower than 0.1V, the chip recognizes this as short

circuit condition and the operating frequency will be folded back. Program

the OVP pin voltage from 0.4V to 1.2V for normal operation.

4

5

FB

LED Current Feedback Input. MP2483 regulates the voltage across the

current sensing resistor between FB and VSS. Connect the current sensing

resistor from the bottom of the LED strings to VSS. The FB pin is connected

to the bottom of the LED strings. The regulation voltage is 0.198V.

5

6

COMP

Output of Error Amplifier. Connect a 1nF or larger capacitor on COMP to

improve the stability and to provide a soft on at start up and PWM dimming.

6

9

RSET

Frequency Set Pin. Connect a resistor to VSS to set the switching frequency

and an 1nF capacitor to VSS to bypass the noise. Leaving this pin open gets

a default operating frequency 1.35MHz.

7

10

EN/DIM

On/Off Control Input and Dimming Command Input. A voltage greater than

0.6V will turn on the chip. Both DC and PWM dimming are implemented on

this pin. When the EN/DIM pin voltage (with respect to INGND) rises from

0.7V to 1.4V, the LED current will change from 0% to 100% of the maximum

LED current. To use PWM dimming, apply a 100Hz to 2kHz square wave

signal with amplitude greater than 1.4V to this pin.

8

11

INGND

Input Ground Reference. This pin is the reference for the EN/DIM signal.

9

12

BST

Bootstrap. A capacitor is connected between SW and BST pin to form a

floating supply across the power switch driver. A 100nF or larger ceramic

capacitor is recommended to provide sufficient energy to drive the power

switch’s gate above the supply voltage.

10

13

SW

Switch Output. SW is the source of the internal MOSFET switch. Connect

this pin to the power inductor and the cathode of the Schottky rectifier.

1,7,8,14

NC

No Connection.

Exposed pad should be connected to VSS in step up/down mode.