MP8124 – 500mA, LNB POWER SUPPLY AND CONTROL REGULATOR

MP8124 Rev. 1.0

www.MonolithicPower.com

19

11/11/2015

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PCB Layout Guidelines

Efficient PCB layout is critical for high-frequency

switching power supplies. A poor layout can

result in reduced performance, excessive EMI,

resistive loss, and system instability. For best

results, refer to Figure 3 and follow the guidelines

below.

1. Keep the boost output loop (IC-SW, D1, C2B,

and IC-PGND) as small as possible.

2. Place the LDO input capacitor (C2A) and the

output capacitor (C4) as close to VBOOST

and VOUT as possible.

3. Connect the LDO output capacitor and the

other signal ground to AGND.

4. Connect the boost output ground to PGND

and then to AGND with a single point.

5. Keep all high-frequency AC current power

traces (VDD, SW, PGND) as short and wide

as possible.

6. Keep the TCAP voltage trace far away from

any noise sources, such as the SW node.

7. Place a small decoupling capacitor as close

to VDD as possible to reduce the input

voltage ripple.

8. Place the bypass capacitor as close to

BYPASS and VOUT as possible.

9. Keep the BST voltage path as short as

possible.

10. Use a wide copper trace for GND to improve

thermal performance. Vias on GND and

copper around and under the MP8124 are

also recommended to improve thermal

performance.

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VBOOST

VOUT

EXTM

13V/18V

Figure 3: Layout Recommendation

Design Example

Table 1 is a design example following the

application guidelines for the specifications below:

Table 1: Design Example

8V - 14V

13V/ 14V/ 18V/ 19V

0A ~ 0.5A

The detailed application schematic is shown in

Figure 4. The typical performance and circuit

waveforms are shown in the Typical Performance

Characteristics

section.

For

more

device

applications, please refer to related evaluation

board datasheet.