MP1475 – SYNCHRONOUS STEP-DOWN CONVERTER

MP1475 Rev. 1.01

www.MonolithicPower.com

13

4/3/2014

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

© 2014 MPS. All Rights Reserved.

PCB layout is very important to achieve stable

operation especially for VCC capacitor and

input capacitor placement. For best results,

follow these guidelines:

1. Use large ground plane directly connect to

GND pin. Add vias near the GND pin if

bottom layer is ground plane.

2. Place the VCC capacitor to VCC pin and

GND pin as close as possible. Make the

trace length of VCC pin-VCC capacitor

anode-VCC capacitor cathode-chip GND

pin as short as possible.

3. Place the ceramic input capacitor close to

IN and GND pins. Keep the connection of

input capacitor and IN pin as short and

wide as possible.

4. Route SW, BST away from sensitive

analog areas such as FB. It’s not

recommended to route SW, BST trace

under chip’s bottom side.

5. Place the T-type feedback resistor R6 close

to chip to ensure the trace which connects

to FB pin as short as possible

Notes:

8) The recommended layout is based on the Figure 7 Typical

Application circuit on the next page.

L1

C2

C1

C1A

R4

C4

C5

Vin

GND

Vout

SW

GND

R5

C2A

GND

SW

BST

GND

VOUT

EN/SYNC

VCC

Design Example

Below is a design example following the

application guidelines for the specifications:

Table 2: Design Example

12V

3.3V

Io

3A

The detailed application schematic is shown in

Figure 8. The typical performance and circuit

waveforms have been shown in the Typical

Performance Characteristics section. For more

device applications, please refer to the related

Evaluation Board Datasheets.