LT3471 Просмотр технического описания (PDF) - Linear Technology

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Компоненты Описание

производитель

LT3471

Dual 1.3A, 1.2MHz Boost/Inverter in 3mm × 3mm DFN

Linear Technology 

LT3471

TYPICAL PERFORMANCE CHARACTERISTICS

Oscillator Frequency

vs Temperature

1.50

1.45

1.40

1.35

1.30

1.25

1.20

1.15

1.10

1.05

1.00

–50 –25

0 25 50 75

TEMPERATURE (°C)

100 125

3471 G07

Peak Switch Current

vs SHDN/SS Voltage

Start-Up Waveform

(Figure 2 Circuit)

2.0

TA = 25°C

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

ISUPPLY

1A/DIV

VOUT1

2V/DIV

VOUT2

5V/DIV

CONTROL 1

AND 2

5V/DIV

0.5ms/DIV

0.2

0

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2.0

VSHDN/SS (V)

3471 G08

3471 G09

PIN FUNCTIONS

FB1N (Pin 1): Negative Feedback Pin for Switcher 1.

Connect resistive divider tap here. Minimize trace area at

FB1N. Set VOUT = VFB1P(1 + R1/R2), or connect to ground

for inverting topologies.

FB1P (Pin 2): Positive Feedback Pin for Switcher 1. Connect

either to VREF or a divided down version of VREF, or connect

to a resistive divider tap for inverting topologies.

VREF (Pin 3): 1.00V Reference Pin. Can supply up to

1mA of current. Do not pull this pin high. Must be locally

bypassed with no less than 0.01μF and no more than 1μF.

A 0.1μF ceramic capacitor is recommended. Use this pin

as the positive feedback reference or connect a resistor

divider here for a smaller reference voltage.

FB2P (Pin 4): Same as FB1P but for Switcher 2.

FB2N (Pin 5): Same as FB1N but for Switcher 2.

SW2 (Pin 6): Switch Pin for Switcher 2 (Collector of in-

ternal NPN power switch). Connect inductor/diode here

and minimize the metal trace area connected to this pin

to minimize EMI.

SHDN/SS2 (Pin 7): Shutdown and Soft-Start Pin. Tie to

1.8V or more to enable device. Ground to shut down. Soft-

start function is provided when the voltage at this pin is

ramped slowly to 1.8V with an external RC circuit.

VIN (Pin 8): Input Supply. Must be locally bypassed.

SHDN/SS1 (Pin 9): Same as SHDN/SS2 but for Switcher 1.

Note: taking either SHDN/SS pin high will enable the part.

Each switcher is individually enabled with its respective

SHDN/SS pin.

SW1 (Pin 10): Same as SW2 but for Switcher 1.

Exposed Pad (Pin 11): Ground. Connect directly to local

ground plane. This ground plane also serves as a heat

sink for optimal thermal performance.

3471fb

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