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LT3493E-3

1.2A, 750kHz Step-Down Switching Regulator in 2mm × 3mm DFN

Linear Technology 

LT3493-3

PI FU CTIO S

FB (Pin 1): The LT3493-3 regulates its feedback pin to

780mV. Connect the feedback resistor divider tap to this

pin. Set the output voltage according to VOUT = 0.78V •

(1 + R1/R2). A good value for R2 is 10k.

GND (Pin 2): Tie the GND pin to a local ground plane below

the LT3493-3 and the circuit components. Return the

feedback divider to this pin.

BOOST (Pin 3): The BOOST pin is used to provide a drive

voltage, higher than the input voltage, to the internal

bipolar NPN power switch.

SW (Pin 4): The SW pin is the output of the internal power

switch. Connect this pin to the inductor, catch diode and

boost capacitor.

VIN (Pin 5): The VIN pin supplies current to the LT3493-3’s

internal regulator and to the internal power switch. This

pin must be locally bypassed.

SHDN (Pin 6): The SHDN pin is used to put the LT3493-

3 in shutdown mode. Tie to ground to shut down the

LT3493-3. Tie to 2.3V or more for normal operation. If the

shutdown feature is not used, tie this pin to the VIN pin.

SHDN also provides a soft-start function; see the Applica-

tions Information section.

Exposed Pad (Pin 7): The Exposed Pad must be soldered

to the PCB and electrically connected to ground. Use a

large ground plane and thermal vias to optimize thermal

performance.

BLOCK DIAGRA

VIN

VIN

5

C2

INT REG

AND

UVLO

ON OFF

R3

SHDN

6

C4

Σ

SLOPE

COMP

OSC

FREQUENCY

FOLDBACK

VC

RQ

SQ

gm

780mV

DRIVER

BOOST

3

Q1

SW

4

D2

C3

L1

D1 C1

VOUT

GND

2

FB

1

R2

R1

3493-3 BD

3493-3f

6

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