LT1310 datasheet(16/28 Pages) LINER

16 / 28 page

LT3580

3580fg

APPLICATIONS INFORMATION

C2, for best load regulation. You can tie the local ground

into the system ground plane at the C3 ground terminal.

The cut ground copper at D1’s cathode is essential to

obtain low noise. This important layout issue arises due

to the chopped nature of the currents flowing in Q1 and

D1. If they are both tied directly to the ground plane before

being combined, switching noise will be introduced into

the ground plane. It is almost impossible to get rid of this

noise, once present in the ground plane. The solution

is to tie D1’s cathode to the ground pin of the LT3580

before the combined currents are dumped in the ground

plane as drawn in Figure 2, Figure 12 and Figure 13. This

single layout technique can virtually eliminate high

frequency “spike” noise, so often present on switching

regulator outputs.

Figure 8. High Speed “Chopped” Switching Path for Boost Topology

Board layout also has a significant effect on thermal re-

sistance. The exposed package ground pad is the copper

plate that runs under the LT3580 die. This is a good thermal

path for heat out of the package. Soldering the pad onto

the board reduces die temperature and increases the power

capability of the LT3580. Provide as much copper area as

possible around this pad. Adding multiple feedthroughs

around the pad to the ground plane will also help. Figures

9 and 10 show the recommended component placement

for the boost and SEPIC configurations, respectively.

Layout Hints for Inverting Topology

Figure 11 shows recommended component placement for

the dual inductor inverting topology. Input bypass capaci-

tor, C1, should be placed close to the LT3580, as shown.

The load should connect directly to the output capacitor,

3580 F08

VOUT

GND

LT3580

VIN

HIGH

FREQUENCY

SWITCHING

PATH

LOAD

LT1310 Datasheet(PDF) 16 Page - Linear Technology

LT1310 Datasheet(HTML) 16 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Datasheet Download

Link URL