MAX779LC Ver la hoja de datos (PDF) - Maxim Integrated

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MAX779LC

Low-Voltage Input, 3V/3.3V/5V/ Adjustable Output, Step-Up DC-DC Converters

Maxim Integrated 

Low-Voltage Input, 3V/3.3V/5V/

Adjustable Output, Step-Up DC-DC Converters

_____________________________Typical Operating Characteristics (continued)

(Circuit of Figure 1, TA = +25°C, unless otherwise noted.)

MAX778L

START-UP TIME

A

B

A: SHDN, 2V/div

B: VOUT, 1V/div

VOUT = 3V

10ms/div

______________________________________________________________Pin Description

PIN

NAME

FUNCTION

1

ILIM

Sets switch current-limit input. Connect to IN for 1A current limit. A resistor from ILIM to IN sets lower

peak inductor currents.

2

IN

Input from battery

3

AGND

Analog ground. Not internally connected to PGND.

4

PGND

Power ground. Must be low impedance; solder directly to ground plane or star ground. Connect to

AGND, close to the device.

5

LX

Collector of 1A NPN power switch and emitter of Active Rectifier PNP.

6

OUT

Voltage output. Connect filter capacitor close to pin.

7

SHDN

Shutdown input disables power supply when low. Also disconnects load from input. Threshold is set at

VIN/2.

N.C.

(MAX777L)

No connect—not internally connected.

8

SEL

(MAX778L)

Selects the main output voltage. 3.3V when hard-wired to AGND, 3.0V when left open.

FB

Feedback input for adjustable-output operation. Connect to an external voltage divider between VOUT

(MAX779L) and AGND.

6 _______________________________________________________________________________________

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