MP4050 – NON-ISOLATED, HIGH BRIGHTNESS, LED DRIVER

MP4050 Rev.1.02

www.MonolithicPower.com

16

1/18/2016

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Table 1: Recommended input capacitance

Surge

voltage

500V

1000V

1500V

2000V

C2

3.3μF

4.7μF

4.7μF

C3

3.3μF

4.7μF

10μF

Show in

Figure11

The demo board can pass the 2000V

differential surge test by adopting below circuit

setup.

(1) Add a MOV RV1(TVR14431)

(2) Add a fuse F1 (SS-5-2A)

1mH/0.1A

L1

4.7

400V

C3

4.7

400V

C2

10/1W

FR1

L

N

MB6S

600V/0.5A

BD1

TVR14431

RV1

F1 250V/2A

85~265VAC

Figure11: 2kV surge solution

Layout Guide

PCB layout is very important to achieve reliable

operation,

good

EMI

and

good

thermal

performance especially in very small size LED

application. The following describe some layout

recommendations.

1. The loop formed between the MP4050,

inductor, freewheeling diode and output

capacitor should be kept as small as

possible for better EMI.

2. Put the AC input far away from the switching

nodes to minimize the noise coupling that

may bypass the input filter.

3. The VCC pin and PRO pin capacitor should

be located physically close to the IC and

GND.

4. Put the feedback resistor next to the PRO

pin as possible and minimize the feedback

sampling loop to minimize the noise coupling

route.

5. In the buck topology, since the MP4050

SOURCE pin is switching nodes, the copper

area connected to SOURCE should be

minimize to minimize EMI with the thermal

constraints of the design.

6. Since MP4050 DRAIN pin is static node

connecting to DC input, the copper area

connected to DRAIN could be maximized to

improve the heat sinking.

Figure 12 shows a sample layout.

Top Layer

Bottom Layer

Figure 12: PCB Layout

Design Example

Below is a design example following the

application

guidelines

based

on

these

specifications:

Table 2: Design Example

85Vac~265Vac

40V

115mA

Figure 13 shows the detailed application

schematic. This circuit is used for the typical

performance and circuit waveforms. For more

device applications, please refer to the related

evaluation board datasheets.