LTC3621/LTC3621-2

1

Rev. D

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TYPICAL APPLICATION

FEATURES

DESCRIPTION

17V, 1A Synchronous

Step-Down Regulator with

3.5µA Quiescent Current

The LTC®3621/LTC3621-2 is a high efficiency 17V, 1A

synchronous monolithic step-down regulator. The switch-

ing frequency is fixed to 1MHz or 2.25MHz with a ±40%

synchronizingrange.Theregulatorfeaturesultralowquies-

cent current and high efficiencies over a wide VOUT range.

The step-down regulator operates from an input voltage

range of 2.7V to 17V and provides an adjustable output

range from 0.6V to VIN while delivering up to 1A of output

current. A user-selectable mode input is provided to allow

the user to trade off ripple noise for light load efficiency;

Burst Mode operation provides the highest efficiency at

lightloads,whilepulse-skippingmodeprovidesthelowest

voltage ripple. The MODE pin can also be used to allow the

user to sync the switching frequency to an external clock.

LTC3621 Options

PART NAME

FREQUENCY

VOUT

LTC3621

1.00MHz

Adjustable

LTC3621-3.3

1.00MHz

3.3V

LTC3621-5

1.00MHz

5V

LTC3621-2

2.25MHz

Adjustable

LTC3621-23.3

2.25MHz

3.3V

LTC3621-25

2.25MHz

5V

Efficiency and Power Loss vs Load at 1MHz

2.5V VOUT with 400mA Burst Clamp, fSW = 1MHz

APPLICATIONS

n

Wide VIN Range: 2.7V to 17V

n

Wide VOUT Range: 0.6V to VIN

n

95% Max Efficiency

n

Low IQ < 3.5µA, Zero-Current Shutdown

n

Constant Frequency (1MHz/2.25MHz)

n

Full Dropout Operation with Low IQ

n

1A Rated Output Current

n

±1% Output Voltage Accuracy

n

Current Mode Operation for Excellent Line and Load

Transient Response

n

Synchronizable to External Clock

n

Pulse-Skipping, Forced Continuous, Burst Mode®

Operation

n

Internal Compensation and Soft-Start

n

Overtemperature Protection

n

Compact 6-Lead DFN (2mm × 3mm) Package or

Thermally-Enhanced MS8E Package with Power

Good Output and Independent SGND Pin

n

AEC-Q100 Qualified for Automotive Applications

n

Portable-Handheld Scanners

n

Industrial and Embedded Computing

n

Automotive Applications

n

Emergency Radio

604k

22pF

1µF

22µF

3621 TA01a

4.7µH

VOUT

2.5V

1A

191k

VIN

RUN

SW

VIN

2.7V TO 17V

LTC3621

GND

FB

MODE/SYNC

INTVCC

10µF

LOAD CURRENT (A)

0

0

10

30

40

50

100

70

0.2

0.4

0.6

3621 TA01b

20

80

90

60

0

0.1

0.6

0.4

0.5

0.3

0.2

0.8

1

EFFICIENCY

POWER LOSS

VOUT = 5V

VOUT = 3.3V

VOUT = 2.5V

VIN = 12V

All registered trademarks and trademarks are the property of their respective owners. Protected

by U.S. patents, including 5481178, 6580258, 6498466, 6611131, 6177787, 5705919,

5847554.