MP174 – NON-ISOLATED OFF-LINE REGULATOR

MP174 Rev. 1.01

www.MonolithicPower.com

17

8/18/2016

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Table 2: Recommended Capacitance

Surge

voltage

500V

1000V

2000V

C1

1μF

2.2μF

3.3μF

C2

1μF

2.2μF

3.3μF

Layout Guide

PCB layout is very important for reliable

operation,

and

good

EMI

and

thermal

performance. Please follow these guidelines to

optimize performance.

1) Minimize the loop area formed by the input

capacitor, IC, freewheeling diode, inductor

and output capacitor.

2) Place the power inductor far away from the

input filter while keeping the loop area to the

inductor to a minimum, see example below.

3) Place a capacitor valued at several hundred

pF between the FB pin and source as close

the IC as possible.

4) Connect the exposed pads or large copper

area with the DRAIN pin to improve thermal

performance.

Top

Bottom Layer

Design Example

Below is a design example following the

application guidelines for the specifications:

Table 3: Design Example

85VAC to 265VAC

12V

300mA

The detailed application schematic is shown in

Figure.10. The typical performance and circuit

waveforms have been shown in the Typical

Performance Characteristics section. For more

device application, please refer to the related

Evaluation Board Datasheets.