LT3970 데이터 시트보기 (PDF) - Linear Technology

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LT3970

40V, 350mA Step-Down Regulator with 2.5µA Quiescent Current and Integrated Diodes

Linear Technology 

FEATURES

n Low Ripple Burst Mode® Operation

2.5μA IQ at 12VIN to 3.3VOUT

Output Ripple < 5mVP-P

n Wide Input Voltage Range: 4.2V to 40V Operating

n Adjustable Switching Frequency: 200kHz to 2.2MHz

n Integrated Boost and Catch Diodes

n 350mA Output Current

n Fixed Output Voltages: 3.3V, 5V

1.8μA IQ at 12VIN

n Accurate 1V Enable Pin Threshold

n Low Shutdown Current: IQ = 0.7μA

n Internal Sense Limits Catch Diode Current

n Power Good Flag

n Output Voltage: 1.21V to 25V

n Internal Compensation

n Small 10-Pin MSOP and (3mm × 2mm) DFN Packages

APPLICATIONS

n Automotive Battery Regulation

n Power for Portable Products

n Industrial Supplies

LT3970/LT3970-3.3/LT3970-5

40V, 350mA Step-Down

Regulator with 2.5µA

Quiescent Current and

Integrated Diodes

DESCRIPTION

The LT®3970 is an adjustable frequency monolithic buck

switching regulator that accepts a wide input voltage

range up to 40V, and consumes only 2.5μA of quiescent

current. A high efficiency switch is included on the die

along with the catch diode, boost diode, and the neces-

sary oscillator, control and logic circuitry. Low ripple Burst

Mode operation maintains high efficiency at low output

currents while keeping the output ripple below 5mV in a

typical application. Current mode topology is used for fast

transient response and good loop stability. A catch diode

current limit provides protection against shorted outputs

and overvoltage conditions. An enable pin with accurate

threshold is available, producing a low shutdown current

of 0.7μA. A power good flag signals when VOUT reaches

90% of the programmed output voltage. The LT3970 is

available in small 10-pin MSOP and 3mm × 2mm DFN

packages.

L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective

owners.

TYPICAL APPLICATION

5V Step-Down Converter

VIN

6V TO 40V

OFF ON

VIN BOOST

LT3970

EN

SW

PG

BD

2.2μF

RT

FB

GND

226k

f = 600kHz

0.22μF

22μH

22pF

1M

316k

VOUT

5V

350mA

22μF

3490 TA01a

Efficiency

90

VIN = 12V

1000

80

100

70

10

60

1

50

0.1

40

0.01

0.1

1

10

LOAD CURRENT (mA)

0.01

100

3970 TA01b

3970fa

1

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