MP4603 – WHITE LED DRIVER FOR LARGE SIZE BACKLIGHTING

MP4603 Rev1.0

www.MonolithicPower.com

14

4/27/2012

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

© 2012 MPS. All Rights Reserved.MP4603

Design Example

This design example shows an LCD TV LED

backlight application. Figure 4 shows the system

power structure block diagram. MPS’s HFC0100

flyback controller controls the flyback, offering 2

provides

a

bias

voltage

(less

than the LED string voltage) for all LED strings

and connects to the anodes. The low output,

LED driver; the MP4603 generates a negative

voltage and connects to the cathode of the LED

strings to drive the LED strings.

HFC0100

Flyback

AC Input

MP4603

LED Driver

MP4603

LED Driver

INGND

INGND

LED1-

LED2-

Figure 4: System Power Block Diagram

Specifications

Flyback Output:

regulation in the multiple output flyback is the

primary cause of the large tolerance.

Output:

2 outputs of 120mA for every string

LED voltage is typical 180V (165V to 195V)

Switching frequency:

~200kHz

Protections:

Open LED string protection

Short LED string protection

MP4603 Operating Range:

Input voltage = 12V

Output voltage = -5V to -55V

LED current = 120mA.

Figure 5 shows the schematic of the MP4603

LED driver stage. JP1 is short and JP2 is open.