or 22pF, whichever is greater.

Standard Application Circuits

Figures 3 and 4 are standard applications circuits for

the MAX1927/MAX1928. Figure 3 illustrates the preset

output voltages (MAX1928), while Figure 4 shows the

adjustable configuration (MAX1927). Table 2 lists part

numbers and suppliers for the components used in

these circuits.

PC Board Layout and Routing

High switching frequencies and large peak currents

make PC board layout a very important part of design.

Good design minimizes EMI, noise on the feedback

paths, and voltage gradients in the ground plane, all of

which can result in instability or regulation errors.

Connect the inductor, input filter capacitor, and output

filter capacitor as close together as possible and keep

their traces short, direct, and wide. Connect their

ground pins at a single common node in a star ground

configuration. The external voltage feedback network

should be very close to the FB pin, within 0.2in (5mm).

Keep noisy traces, such as those from the LX pin, away

from the voltage feedback network. Position the bypass

capacitors as close as possible to their respective pins

to minimize noise coupling. For optimum performance,

place input and output capacitors as close to the

device as possible. Connect GND and PGND to the

highest quality system ground. The MAX1928 evalua-

tion kit illustrates an example PC board layout and rout-

ing scheme.

Chip Information

TRANSISTORS: 3282

PROCESS: BiCMOS

C

RC

R

f

ESR

OUT

C

=

×

Low-Output-Voltage, 800mA, PWM Step-Down

DC-DC Converters

______________________________________________________________________________________

11

PART

PART NUMBER

MANUFACTURER

PHONE

WEBSITE

Inductor

CDRH3D16-4R7

Sumida

USA 847-956-0666

Japan 81-3-3607-5111

www.sumida.com

Input/Output Capacitors

JMK212BJ106MG

Taiyo Yuden

408-573-4150

www.t-yuden.com

COMP Capacitor

GRM1881X1H561J

Murata

770-436-1300

www.murata.com

REF Capacitor

EMK107BJ104KA

Taiyo Yuden

408-573-4150

www.t-yuden.com

Table 2. Suggested Parts/Suppliers