MP2483 – 2.5A, 55V, PROGRAMABLE FREQUENCY WHITE LED DRIVER
MP2483 Rev. 1.0 www.MonolithicPower.com 4
12/25/2013 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2013 MPS. All Rights Reserved.
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.