MP4603 – WHITE LED DRIVER FOR LARGE LCD TV BACKLIGHTS

MP4603 Rev. 1.0

www.MonolithicPower.com

8

4/27/2012

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2012 MPS. All Rights Reserved.MP4603

PIN FUNCTIONS

Pin #

SOIC16

Pin #

TSSOP

16-EP

Name

Description

2

1

VIN

Positive Voltage Input. Requires a decoupling capacitor to prevent large input-

voltage spikes.

1

2

FAULT

Fault Condition Output. Open drain with reference to INGND. FAULT is high-Z

during normal operation, and pulled to INGND when LED short protection or

LED open protection trigger.

3

3

INGND

Input Ground Reference.

4

4

SYN

Frequency Synchronization Input. The switching frequency can be synchronized

with an external clock. Multiple ICs’ frequencies can also be synchronized

without the external clock by connecting all the SYN pins together. They follow

the highest set frequency.

5

5

PWM

PWM Dimming Input. Apply a 100Hz to 50kHz square wave signal with

amplitude greater than 2.2V. The PWM pin voltage is high if left floating.

6

6

EN

Enable Input Pin. A voltage greater than 1.5V will turn on the chip.

7

7

ADIM

Analog Dimming Input. A voltage in range of 0V to 1.2V on ADIM pin adjusts the

LED current from 0 to 100%. The ADIM pin voltage is high (about 3.3V) if left

floating.

8

8

FST

Frequency Set. A resistor from FST to VSS sets the switching frequency if there

is no SYN input. If left open, switching frequency reverts to an internal default

value.

9

9

SLOPE

Programmable Slope Compensation. Connect a resistor from SLOPE to VSS to

set the slope-compensation peak amplitude. If left open, slope compensation

reverts to an internal default value.

10

10

COMP

Error Amplifier Output. Connect a capacitor ≥1nF from the COMP pin to VSS to

improve the stability and to provide a soft-start on start-up or for PWM dimming.

11

11

FB

LED Current Feedback. The MP4603 regulates the voltage across the current

sensing resistor between FB and VSS with 200mV. If the FB voltage exceeds

300mV for 450µs or exceeds 600mV, LED short protection triggers.

12

12

OVP

Over Voltage Protection. Use one external resistor voltage divider from the

output to VSS to program the OVP threshold. This voltage references VSS.

When the OVP pin voltage reaches the 1.2V threshold, the switch turns off and

the IC latches off. When the OVP pin voltage falls below 0.4V and the FB pin

voltage is less than 0.1V, the chip frequency folds back. Program the OVP pin

voltage from 0.4V to 1.2V for normal operation.

13

13

DGD

LED Dimming-Switch Gate Drive Output.

14

14

VSS

Negative Voltage Output. The voltage reference for OVP, FB, COMP, SLOPE,

DGD and FST.

15

15

SW

Switch Output. The source of the internal MOSFET switch. Connect to the power

inductor and cathode of the Schottky rectifier.

16

16

BST

Bootstrap. Connect a capacitor between the SW and BST pins to form a floating

supply across the power switch driver.