MP4653—REAL LIPS CC/CV MODE LLC TV LED DRIVER

MP4653 Rev 1.01

www.MonolithicPower.com

13

6/28/2012

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© 2012 MPS. All Rights Reserved.

PIN FUNCTIONS

Pin #

Name

Description

1

SS

Soft Start. This pin functions soft start and also sets the operating frequency together with

in series to this pin. The sourcing current of this pin together with the sourcing current of

on FSET pin sets the operating frequency; the resistor Rss and the capacitor Css functions

the soft start.

The normal voltage on this pin is 1.49V and is pulled low to 0V at bus voltage stage fault

condition. The Rss and Css network sets the start up operating frequency and the soft start

time.

2

FSET

Frequency Set. Connect a resistor from this pin to GND. The operating frequency is

determined by the sourcing current through this pin and SS pin. The voltage of FSET pin is

programmed by the current control loop and the voltage control loop, and so does the

operating frequency.

3

VOCP

Over current protection of bus stage. This pin senses the secondary current of the bus stage,

when the VOCP voltage is lower than -100mV, IC triggers bus stage protection.

4

VFB

Bus voltage feedback. This pin feeds back the bus voltage for regulation. MP4653

automatically samples the VFB voltage at PWM ON interval and uses it as the reference

voltage of the bus voltage control loop at PWM OFF interval.

The voltage on VFB pin is also used for over voltage protection of bus voltage stage. When

the voltage on VFB pin exceeds 2.4V, the over voltage protection of bus voltage stage is

triggered.

5

VCOMP

Feedback Compensation Node of voltage control loop. Connect a compensation capacitor or

a R-C network from this pin to GND.

VCOMP pin is also used as the hiccup timer for the fault protection of the Bus voltage stage.

When fault condition occurs in the bus voltage stage, the VCOMP is disconnected from the

internal voltage loop and the hiccup timer for the voltage bus voltage stage starts. An internal

current source charges VCOMP until 3V and then discharges it to 0.45V.

6

ICOMP

Feedback Compensation Node of current control loop. Connect a compensation capacitor or

a R-C network from this pin to GND.

ICOMP pin is also used as the hiccup timer for the LED stage protection. When fault

condition of the LED stage occurs, the ICOMP pin is disconnected from the internal amplifier

and LED stage hiccup timer starts. An internal current source charges ICOMP until 3V and

then discharges it to 0.45V.

7

IFB

LED Current Feedback Input. This pin feeds back the LED current through a sensing resistor.

The internal error amplifier sinks a current from the ICOMP pin proportional to the absolute

value of the voltage at this pin. The average voltage at this pin is regulated to the reference

voltage (controlled by the A-dim voltage, 0.2V when A-dim is high).

The voltage on this pin is also used for over LED current detection. When the voltage on this

pin gets higher than 0.3V for 200

triggers the LED stage protection.

8

SSD

Short string protection. This pin feeds back the secondary side current of the LED driver

stage. When the voltage on this pin is less than -200mV, IC triggers the LED driver stage

protection.

9

VLED4 Voltage feedback of LED string4.

10

VLED3 Voltage feedback of LED string3.

11

VLED2 Voltage feedback of LED string2.