MP2104 – 1.7MHz 600mA SYNCHRONOUS STEP-DOWN CONVERTER

NOTICE: MPS believes the information in this document to be accurate and reliable. However, it is subject to change without

notice. Contact MPS for current specifications. MPS encourages users of its products to ensure that third party Intellectual

Property rights are not infringed upon when integrating MPS products into any application. MPS cannot assume any legal

responsibility for any said applications.

MP2104 Rev. 1.0

Monolithic Power Systems, Inc.

9

10/4/05

983 University Avenue, Building A, Los Gatos, CA 95032 USA

© 2004 MPS, Inc.

Tel: 408-357-6600

♦ Fax: 408-357-6601 ♦ www.MonolithicPower.com

TM

Input Capacitor Selection

The input capacitor reduces the surge current

drawn from the input and switching noise from

the device. The input capacitor impedance at

the switching frequency shall be less than input

source impedance to prevent high frequency

switching current passing to the input. Ceramic

capacitors with X5R or X7R dielectrics are

highly recommended because of their low ESR

and small temperature coefficients. For most

applications, a 4.7µF capacitor is sufficient.

Output Capacitor Selection

The output capacitor keeps output voltage

ripple small and ensures regulation loop stable.

The output capacitor impedance shall be low at

the switching frequency. Ceramic capacitors

with X5R or X7R dielectrics are recommended.

()

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

×

×

+

×

×

×

−

×

≤

∆

3

C

f

8

1

ESR

L

f

V

V

V

V

V

OSC

OSC

IN

OUT

IN

OUT

OUT

PC Board Layout

The high current paths (GND, IN and SW)

should be placed very close to the device with

short, direct and wide traces. Input capacitor C1

needs to be as close as possible to the IN and

GND pins. The external feedback resistors shall

be placed next to the FB pin. Keep the

switching node SW short and away from the

feedback network. Figure 3 illustrates an

example of PCB layout and signal routing.

Figure 3—MP2104 Suggested Layout

For the fixed output versions (MP2104DJ-1.5

and MP2104-1.8), R1 is shorted and R2 is

open.

MP2104

SW

FB

EN

GND

IN

OUTPUT

1.8V

600mA

INPUT

2.5V - 6V

MP2104_F04

OFF ON

3

5

2

1

4

100

90

80

70

60

50

40

30

20

10

0

10

100

1000

LOAD CURRENT (mA)

MP2104-EC02

Efficiency vs

Load Current

(L = 10µH for Higher Light-Load Efficiency)