LT3479EDE データシートの表示（PDF） - Linear Technology

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LT3479EDE

3A, Full Featured DC/DC Converter with Soft-Start and Inrush Current Protection

Linear Technology 

LT3479

PIN FUNCTIONS (DFN/TSSOP)

SW (Pins 1, 2/Pins 1, 2): Switch Pins. Collector of the

internal NPN power switch. Connect the inductor and diode

here and minimize the metal trace area connected to this

pin to minimize electromagnetic interference.

L (Pin 3/Pin 3): Inductor Pin. Connect the inductor to

this pin.

VS (Pin 4/Pin 4): Inductor Supply. Must be locally bypassed.

Powers the switch and the inductor. In case only one supply

voltage is available, tie VIN and VS together.

VIN (Pin 5/Pin 5): Input Supply. Must be locally bypassed.

Powers the internal control circuitry.

RT (Pin 6/Pin 6): Timing Resistor Pin. Adjusts the switch-

ing frequency. Do not leave this pin open. See Table 4 for

RT values and switching frequencies.

SHDN (Pin 7/Pin 7): Shutdown. Tie to 1.5V or greater to

enable the device. Tie below 0.3V to turn off the device.

VREF (Pin 8/Pin 9): Bandgap Voltage Reference. Internally

set to 1.235V. Connect this pin to FBP if generating a posi-

tive output, or to an external resistor divider if generating a

negative voltage. This pin can provide up to 100μA of current

and can be locally bypassed with a 100pF capacitor.

FBP (Pin 9/Pin 10): The Noninverting Input to the Error

Amplifier. Connect resistive divider tap here for negative

output voltage.

FBN (Pin 10/Pin 11): The Inverting Input to the Error

Amplifier. Connect resistive divider tap here for positive

output voltage.

VC (Pin 11/Pin 12): Compensation Pin for Error Amplifier.

Connect a series RC from this pin to GND. Typical values

are 10kΩ and 2.2nF.

SS (Pin 12/Pin 13): Soft-Start. Place a soft-start capacitor

here. Leave floating if not in use.

GND (Pins 13, 14/Pins 8, 14, 15, 16): Ground. Tie directly

to local ground plane.

Exposed Pad (Pin 15/Pin 17): Power Ground. Must be

connected to electrical PCB ground.

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