LM2674 datasheet(23/26 Pages) NSC

23 / 26 page

Application Information (Continued)

Layout is very important in switching regulator designs. Rap-

idly switching currents associated with wiring inductance can

generate voltage transients which can cause problems. For

minimal inductance and ground loops, the wires indicated by

heavy lines (in Figure 2 and Figure 3) should be wide

printed circuit traces and should be kept as short as

possible. For best results, external components should be

located as close to the switcher IC as possible using ground

plane construction or single point grounding.

If open core inductors are used, special care must be

taken as to the location and positioning of this type of induc-

tor. Allowing the inductor flux to intersect sensitive feedback,

IC ground path, and C

OUT wiring can cause problems.

When using the adjustable version, special care must be

taken as to the location of the feedback resistors and the

associated wiring. Physically locate both resistors near the

IC, and route the wiring away from the inductor, especially an

open core type of inductor.

LLP Package Devices

The LM2674 is offered in the 16 lead LLP surface mount

package to allow for increased power dissipation compared

to the SO-8 and DIP.

The Die Attach Pad (DAP) can and should be connected to

PCB Ground plane/island. For CAD and assembly guide-

lines

refer

Application

Note

AN-1187

http://

power.national.com.

LM2674 데이터시트(PDF) 23 Page - National Semiconductor (TI)