MP4034 – OFFLINE LED DRIVER

MP4034 Rev. 1.02

www.MonolithicPower.com

15

12/4/2013

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PCB Layout Guide

PCB layout is very important to achieve reliable

operation,

and

good

EMI

and

thermal

performance. The use design guide as follows

to help optimize performance.

1. Minimize the loop area formed by the input

capacitor, the MP4034 drain-source, and the

primary winding to reduce EMI noise.

2. The copper area connected to source pins

acts as a heat sink. Provide a large copper area

to improve the thermal performance.

3. Minimize the clamp circuit loop to reduce EMI.

4. Minimize the secondary loop area of the

output diode and output filter to reduce the EMI

noise. In addition, provide a sufficient copper

area at the anode and cathode terminal of the

output diode for heat dissipation.

5. Place the AC input away from the switching

nodes to minimize the noise coupling that may

bypass the input filter.

6. Place the bypass capacitor as close as

possible to the IC and source.

7. Place the feedback resistors at the FB pin

and minimize the feedback sampling loop area

to minimize noise coupling.

8. Use a single point connection at the negative

terminal of the input filter capacitor for the

MP4034 source pin and bias winding return.

Figure 13 shows a layout example.

Top Layer

Bottom Layer

Figure 13: PCB Layout

Design Example

Below are design examples following the

application

guidelines

for

the

given

specifications:

Table 1: Design Example

Example 1

85VAC-265VAC

40V

0.13A

Example 2

85VAC-265VAC

10V

0.35A

Figure 14 and Figure 15 show the detailed

isolated application, while Figure 16 and Figure

17 show the detailed non-isolated application.

These examples were used in the Typical

Performance Characteristics section. For more

applications, please refer to the related

evaluation board datasheets.