MAX1896 Ver la hoja de datos (PDF) - Maxim Integrated

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Fabricante

MAX1896

1.4MHz SOT23 Current-Mode Step-Up DC-DC Converter

Maxim Integrated 

1.4MHz SOT23 Current-Mode

Step-Up DC-DC Converter

Typical Operating Characteristics (continued)

(Circuit of Figure 1, VIN = 3.3V, TA = +25°C, unless otherwise noted.)

STARTUP WAVEFORM

WITH SOFT-START

IOUT = 100mA

SHDN

5V/div

OUTPUT

VOLTAGE

5V/div

INDUCTOR

CURRENT

500mA/div

2ms/div

VIN = 3.3V, CSS = 33nF,

COUT = 3.3µF TANTALUM + 0.1µF CERAMIC

CIRCUIT OF FIGURE 3

SWITCHING WAVEFORM

LX VOLTAGE

5V/div

OUTPUT

VOLTAGE

AC-COUPLED

200mV/div

INDUCTOR

CURRENT

500mA/div

IOUT = 150mA

400ns/div

VIN = 5V,

COUT = 0.1µF CERAMIC + 2.2µF CERAMIC

MAXIMUM OUTPUT CURRENT

vs. INPUT VOLTAGE

600

500

400

300 VOUT = 5V

VOUT = 12V

200

MAXIMUM OUTPUT

100

CURRENT DEFINED AT

90% OF NO LOAD

OUTPUT VOLTAGE

0

2.5 3.0 3.5 4.0 4.5 5.0 5.5

INPUT VOLTAGE (V)

Pin Description

PIN

NAME

FUNCTION

1

LX

Power Switching Connection. Connect LX to the inductor and output rectifier. Connect components

as close to LX as possible.

2

GND

Ground

3

FB

Feedback Input. Connect a resistive voltage-divider from the output to FB to set the output voltage.

See the Setting the Output Voltage section.

Shutdown Input. Drive SHDN low to turn off the converter. To automatically start the converter,

4

SHDN

connect SHDN to IN. Drive SHDN with a slew rate of 0.1V/µs or greater. Do not leave SHDN

unconnected. SHDN draws up to 50µA.

5

SS

Soft-Start Input. Connect a soft-start capacitor from SS to GND to soft-start the converter. Leave SS

open to disable the soft-start function. See the Soft-Start section.

6

IN

Internal Bias Voltage Input. Connect IN to the input voltage source. Bypass IN to GND with a

1µF or greater capacitor as close to IN as possible.

_______________________________________________________________________________________ 5

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