MP4601 – WHITE LED DRIVER FOR LARGE SIZE TV BACKLIGHTING

MP4601 Rev. 1.0

www.MonolithicPower.com

6

1/28/2011

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

© 2011 MPS. All Rights Reserved.

PIN FUNCTIONS

Pin #

SOIC16

Pin #

TSSOP

16-EP

Name

Description

2

1

VIN

Positive Voltage Input Pin. A decoupling cap is needed to prevent large voltage

spikes from appearing at the input.

1

2

FAULT

Fault condition output, open drain with reference to INGND. FAULT is high-Z

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

triggered.

3

3

INGND

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

4

4

SYN

Frequency Synchronization Input Pin. The switching frequency can be

synchronized with an external clock, which frequency is higher than the set

frequency with FST resistor. Multiple ICs’ frequencies can also be synchronized

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

highest set frequency.

5

5

DIM

PWM Dimming and Analog Dimming Input Pin.

For digital dimming, apply a 100Hz to 50kHz square wave signal with amplitude

greater than 1.5V to DIM pin.

For analog dimming, apply a voltage between 0.7V and 1.5V to DIM pin. When

DIM voltage changes from 0.7V to 1.5V, the internal reference for FB regulation

changes from 0 to 200mV. A voltage higher than 1.5V at this pin doesn’t modify

the internal reference anymore.

For combined PWM and analog dimming to get a further high dimming ratio,

apply a 100Hz to 50kHz square wave signal with amplitude from 0.7V to 1.5V to

DIM pin.

DIM pin voltage is high (about 3.3V) if it is floating.

6

6

EN

Enable Input Pin. A voltage greater than 0.6V will turn on the chip.

7

7

FST

Frequency Setting Pin. A resistor from FST to VSS setting the switching

frequency if there is no SYN input. If left open, switching frequency will be set to

internal default value.

8

8

SLOPE

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

VSS sets slope compensation peak amplitude. If left open, slope compensation

will be set internal default value.

9

9

OCP

the cycle-by-cycle current limit of the inside power FET. If left open, the current

limit is the default value of 2.5A.

10

10

COMP

Output of error amplifier. Connect a 1nF or larger capacitor on COMP pin to VSS

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

11

11

FB

LED Current Feedback Input. MP4601 regulates the voltage across the current

sensing resistor between FB and VSS with 200mV. If FB voltage is higher than

300mV for 480us or FB voltage is higher than 600mV, it triggers the LED short

protection.

12

12

OVP

Over Voltage Protection Pin. Use one external resistor voltage divider across

INGND and VSS to program OVP threshold. Its voltage is referred to VSS.

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

will recover when OVP voltage decreases below 1.1V. When the OVP pin

voltage is lower than 0.4V and FB pin voltage is lower than 0.1V, the chip

frequency will be folded back. Program the OVP pin voltage from 0.4V to 1.2V

for normal operation.