LM2599 datasheet(19/31 Pages) NSC

Part #	LM2599

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

PDF	31 Pages

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Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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Application Information (Continued)

the narrow pulses and ramp up in a controlled manner. This

is a very useful feature in some switcher topologies that re-

quire large startup currents (such as the inverting configura-

tion) which can load down the input power supply.

Note: The lower curve shown in

Figure 13 shows the Soft-start region from

0% to 100%. This is not the duty cycle percentage, but the output volt-

age percentage. Also, the Soft-start voltage range has a negative tem-

perature coefficient associated with it. See the Soft-start curve in the

electrical characteristics section.

4. Normal operation. Above 2.8V, the circuit operates as a

standard Pulse Width Modulated switching regulator. The

capacitor will continue to charge up until it reaches the inter-

nal clamp voltage of approximately 7V. If this pin is driven

from a voltage source, the current must be limited to about

1 mA.

DS012582-31

FIGURE 13. Soft-start, Delay, Error, Output

DS012582-32

FIGURE 14. Timing Diagram for 5V Output

LM2599 Datasheet(PDF) 19 Page - National Semiconductor (TI)