lm2599sx-5.0 National Semiconductor Corporation, lm2599sx-5.0 Datasheet - Page 9

• Manufacturer Part Number: lm2599sx-5.0
• Description: Simple Switcher Power Converter 150 Khz 3a Step-down Voltage Regulator, With Features
• Manufacturer: National Semiconductor Corporation

Test Circuit and Layout Guidelines
where V
Select R
Component Values shown are for V
V
C
C
D1 — 5A, 30V Schottky Rectifier, 1N5824
L1 — 68 µH, L38
R
R
C
R
Typical Values
C
C
R
As in any switching regulator, layout is very important. 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 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 lC 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,
lC groundpath and C
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. (See application section for more
information.)
OUT
IN
OUT
1
2
FF
FF
SS
DELAY
PULL UP
:
— 1 k , 1%
— 7.15k, 1%
— 0.1 µF
— 3.3 nF, See Application Information Section
— 3 k , See Application Information Section
:
= 10V, I
— 470 µF, 35V, Aluminum Electrolytic Nichicon “PL Series”
— 0.1 µF
REF
1
— 220 µF, 35V Aluminum Electrolytic, Nichicon “PL Series”
— 4.7k
to be approximately 1 k , use a 1% resistor for best stability.
= 1.23V
LOAD
= 3A.
OUT
wiring can cause problems.
IN
= 20V,
FIGURE 1. Standard Test Circuits and Layout Guides
Adjustable Output Voltage Versions
(Continued)
9
DS012582-25
www.national.com