MP2162A – 2A, 6V, 1.5MHz SYNCHRONOUS STEP-DOWN CONVERTER

MP2162A Rev. 1.03

www.MonolihicPower.com

13

6/30/2016

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

© 2016 MPS. All Rights Reserved.

LOAD

OUT

OUT

IN

IN

SIN

IV

V

V1

fC1

V

V







 







(7)

Selecting the Output Capacitor

The output capacitor (C2) is required to

maintain the DC output voltage. Ceramic, low

ESR capacitors are recommended to keep the

output voltage ripple low. The output voltage

ripple can be estimated by Equation (8):

OUT

OUT

OUT

ESR

S1

IN

S

VV

1

V1

R

fL

V

8 f

C2







 









 

equivalent series resistance (ESR) value of the

output capacitor.

When using ceramic capacitors, the impedance

at the switching frequency is dominated by the

capacitance, which mainly causes output

voltage ripples. For simplification, the output

voltage ripple can be estimated with Equation

(9):

OUT

OUT

OUT

2

IN

S1

VV

ΔV1

V

8f

L

C2



 



 



(9)

When using tantalum or electrolytic capacitors,

the ESR dominates the impedance at the

switching frequency. For simplification, the

output ripple can be approximated with

Equation (10):

OUT

OUT

OUT

ESR

IN

S1

VV

ΔV1

R

fL

V



 









(10)

The characteristics of the output capacitor

affect the stability of the regulation system.

PCB Layout Guidelines

Efficient PCB layout is critical for achieving

stable operation. A poor layout design can

result in poor line or load regulation and stability

issues. For best results, refer to Figure 3 and

follow the guidelines below:

1. Place the high-current paths (GND, VIN,

and SW) as close to the device as

possible with short, direct, and wide

traces.

2. Place the input capacitor as close to VIN

and GND as possible.

3. Place the external feedback resistors

next to FB.

4. Keep the switching node (SW) short and

away from the feedback network.

EN

GND

OUT

SW

VIN

1

2

3

4

8

7

6

5

PG

R1

C2

R2

C1

Figure 3: PCB Layout Recommendation

Design Example

Below is a design example following the

application guidelines for the specifications

below:

Table 2: Design Example

5V

1.2V

1500kHz

The detailed application schematic is shown in

Figure 4. The typical performance and circuit

waveforms

are

shown

in

the

Typical

Performance Characteristics section on page 5.

For more device applications, please refer to

the related evaluation board datasheets.