MCP1650 datasheet(20/28 Pages) MICROCHIP

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MCP1650/51/52/53

DS21876A-page 20

 2004 Microchip Technology Inc.

6.0

TYPICAL LAYOUT

FIGURE 6-1:

MCP1650/51/52/53 Application Schematic.

When designing the physical layout for the MCP1650/

51/52/53, the highest priority should be placing the

boost power train components in order to minimize the

size of the high current paths. It is also important to pro-

vide ground-path separation between the large-signal

power train ground and the small signal feedback path

and feature grounds. In some cases, additional filtering

on the VIN pin is helpful to minimize MCP1650/51/52/53

input noise.

In this layout example, the critical power train paths are

from input to output, +VIN

_1 to F

1 to C2 to L1 to Q1 to

GND. Current will flow in this path when the switch (Q1)

is turned on. When Q1 is turned off, the path for current

flow will quickly change to +VIN

_1 to F

1 to L1 to D1 to

C1 to R4 to GND. When starting the layout for this appli-

cation, both of these power train paths should be as

short as possible. The C2, Q1 and R4 GND connections

should all be connected to a single “Power Ground”

plane to minimize any wiring inductance.

Bold traces are used to represent high-current

connections and should be made as wide as is

practical.

R1 and C3 is an optional filter that reduces the

switching noise on the VIN pin of the MCP1650/51/52/

53. This should be considered for high-power

applications (> 1W) and bootstrap applications where

VIN of the MCP1650/51/52/53 is supplied by the output

voltage of the boost regulator.

The feedback resistor divider that sets the output

voltage should be considered sensitive and be routed

away from the power-switching components discussed

previously.

As shown in the diagram, R6, R8 and the GND pin of

the MCP1650/51/52/53 should be returned to an

analog ground plane.

The analog ground plane and power ground plane

should be connected at a single point close to the input

capacitor (C2).

Single-Cell Li-Ion

Input (2.8V to 4.8V)

+5V Output @ 1A

Low Input

Coilcraft

DO1813HC

PGND

AGND

0.1µ

47µ

TP1

IN_1

TP2

OUT_1

TP4

GND

73.2K

49.9K

AGND

3.3 µH

B330ADIC

3.09K

562

MCP1651_MSOP

LED

MCP1651R

(+2.8V to +4.8V Input to +5V Output @ 1A)

2A Power Train Path

IRLML2502

/SHDN

LBI

GND

EXT

/LBO

49.9K

Keep Away From Switching Section

TP5

/SHDN1

0.1

TP3

GND

47µ

FUSE

100

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