LM2599 datasheet(28/31 Pages) NSC

Part #	LM2599

Description	SIMPLE SWITCHER Power Converter 150 kHz 3A Step-Down Voltage Regulator, with Features

PDF	31 Pages

Scroll/Zoom	100%

Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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28 / 31 page

Application Information (Continued)

quirement however, that there be a minimum load of 1.2A on

the regulated positive output for the charge pump to work

correctly. Also, resistor R1 is required to limit the charging

current of C1 to some value less than the LM2599 current

limit (typically 4.5A).

This method of generating a negative output voltage without

an additional inductor can be used with other members of

the Simple Switcher Family, using either the buck or boost

topology.

TYPICAL THROUGH HOLE PC BOARD LAYOUT, FIXED OUTPUT (1X SIZE), DOUBLE SIDED

DS012582-48

FIGURE 31. Charge Pump for Generating a

Low Current, Negative Output Voltage

DS012582-51

CIN:

— 470 µF, 50V, Aluminum Electrolytic Panasonic, “HFQ Series”

COUT:

— 330 µF, 35V, Aluminum Electrolytic Panasonic, “HFQ Series”

D1:

— 5A, 40V Schottky Rectifier, 1N5825

L1:

— 47 µH, L39, Renco, Through Hole

RPULL UP:

— 10k

CDELAY:

— 0.1 µF

CSD/SS:

— 0.1 µF

Thermalloy Heat Sink #7020

LM2599 Datasheet(PDF) 28 Page - National Semiconductor (TI)