2024年5月8日发(作者：平板电脑什么牌子好用又便宜)

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FEATURES

High Effi ciency (No Sense Resistor Required)

n

Wide Input Voltage Range: 2.5V to 36V

n

Current Mode Control Provides Excellent

Transient Response

n

High Maximum Duty Cycle (92% Typ)

n

±2% RUN Pin Threshold with 100mV Hysteresis

n

±1% Internal Voltage Reference

n

Ultra Low Pulse Skip Threshold for Wide Input

Range Applications

n

Micropower Shutdown: I = 10μA

Q

n

Programmable Operating Frequency

(50kHz to 1MHz) with One External Resistor

n

Synchronizable to an External Clock Up to 1.3 × f

OSC

®

n

User-Controlled Pulse Skip or Burst Mode Operation

n

Internal 5.2V Low Dropout Voltage Regulator

n

Output Overvoltage Protection

n

Capable of Operating with a Sense Resistor for High

Output Voltage Applications

n

Small 10-Lead MSOP Package

n

LTC1871-1

Wide Input Range, No R

SENSE

™

Current Mode Boost,

Flyback and SEPIC Controller

DESCRIPTION

The LTC

®

1871-1 is a wide input range, current mode, boost,

fl yback or SEPIC controller that drives an N-channel power

MOSFET and requires very few external components. It

eliminates the need for a current sense resistor by utilizing

the power MOSFET’s on-resistance, thereby maximizing

effi ciency. Higher output voltage applications are possible

with the LTC1871-1 by connecting the SENSE pin to a

resistor in the source of the power MOSFET.

The IC’s operating frequency can be set with an external

resistor over a 50kHz to 1MHz range, and can be synchro-

nized to an external clock using the MODE/SYNC pin.

The LTC1871-1 differs from the LTC1871 by having a

lower pulse skip threshold, making it ideal for applica-

tions requiring constant frequency operation at light

loads. The lower pulse skip threshold also helps maintain

constant frequency operation in applications with a wide

input voltage range. For applications requiring primary-

to-secondary side isolation, please refer to the LTC1871

datasheet.

The LTC1871-1 is available in the 10-lead MSOP package.

L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.

No R

SENSE

is a trademark of Linear Technology Corporation. All other trademarks are the

property of their respective owners.

APPLICATIONS

Telecom Power Supplies

n

Portable Electronic Equipment

n

TYPICAL APPLICATION

V

IN

3.3V

L1

1μH

D1

RUN

R

C

22k

C

C1

6.8nF

C

C2

47pF

R2

37.4k

1%

R1

12.1k

1%

I

TH

LTC1871-1

FB

FREQ

R

T

80.6k

1%

MODE/SYNC

INTV

CC

GATE

GND

C

VCC

4.7μF

X5R

SENSE

V

IN

V

OUT

5V

7A

(10A PEAK)

C

OUT2

22μF

6.3V

X5R

×2

GND

100

90

80

E

F

F

I

C

I

E

N

C

Y

(

%

)

70

60

50

40

30

0.001

PULSE-SKIP

MODE

Burst Mode

OPERATION

Effi ciency of Figure 1

+

C

IN

22μF

6.3V

×2

M1

C

OUT1

150μF

6.3V

×4

+

18711 F01a

C

IN

: TAIYO YUDEN JMK325BJ226MM

C

OUT1

: PANASONIC EEFUEOJ151R

C

OUT2

: TAIYO YUDEN JMK325BJ226MM

D1: MBRB2515L

L1: SUMIDA CEP125-H 1R0MH

M1: FAIRCHILD FDS7760A

0.010.11

OUTPUT CURRENT (A)

10

18711 F01b

Figure 1. High Effi ciency 3.3V Input, 5V Output Boost Converter (Bootstrapped)

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元器件交易网

LTC1871-1

ABSOLUTE MAXIMUM RATINGS

(Note 1)

PIN CONFIGURATION

TOP VIEW

RUN

I

TH

FB

FREQ

MODE/

SYNC

1

2

3

4

5

10

9

8

7

6

SENSE

V

IN

INTV

CC

GATE

GND

V

IN

Voltage ............................................... –0.3V to 36V

INTV

CC

Voltage ............................................ –0.3V to 7V

INTV

CC

Output Current .......................................... 50mA

GATE Voltage ............................ –0.3V to V

INTVCC

+ 0.3V

I

TH

, FB Voltages ....................................... –0.3V to 2.7V

RUN, MODE/SYNC Voltages ....................... –0.3V to 7V

FREQ Voltage ............................................–0.3V to 1.5V

SENSE Pin Voltage .................................... –0.3V to 36V

Operating Junction Temperature Range (Note 2)

LTC1871E-1 .........................................–40°C to 85°C

LTC1871I-1 ........................................–40°C to 125°C

Junction Temperature (Note 3) ............................ 125°C

Storage Temperature Range ...................–65°C to 150°C

Lead Temperature (Soldering, 10 sec) ..................300°C

MS PACKAGE

10-LEAD PLASTIC MSOP

T

JMAX

= 125°C, θ

JA

= 120°C/W

ORDER INFORMATION

LEAD FREE FINISH

LTC1871EMS-1#PBF

LTC1871IMS-1#PBF

LEAD BASED FINISH

LTC1871EMS-1

LTC1871IMS-1

TAPE AND REEL

LTC1871EMS-1#TRPBF

LTC1871IMS-1#TRPBF

TAPE AND REEL

LTC1871EMS-1#TR

LTC1871IMS-1#TR

PART MARKING

LTCTV

LTCTV

PART MARKING

LTCTV

LTCTV

PACKAGE DESCRIPTION

10-Lead Plastic MSOP

10-Lead Plastic MSOP

PACKAGE DESCRIPTION

10-Lead Plastic MSOP

10-Lead Plastic MSOP

TEMPERATURE RANGE

–40°C to 85°C

–40°C to 125°C

TEMPERATURE RANGE

–40°C to 85°C

–40°C to 125°C

Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.

For more information on lead free part marking, go to:

/leadfree/

For more information on tape and reel specifi cations, go to:

/tapeandreel/

The

l

denotes the specifi cations which apply over the full operating

temperature range, otherwise specifi cations are at T

A

= 25°C. V

IN

= 5V, V

RUN

= 1.5V, R

FREQ

= 80k, V

MODE/SYNC

= 0V, unless otherwise specifi ed.

SYMBOL

V

IN(MIN)

I

Q

PARAMETER

Minimum Input Voltage

I-Grade (Note 2)

Input Voltage Supply Current

Continuous Mode

(Note 4)

V

MODE/SYNC

= 5V, V

FB

= 1.4V, V

ITH

= 0.75V

V

MODE/SYNC

= 5V, V

FB

= 1.4V, V

ITH

= 0.75V,

I-Grade (Note 2)

Burst Mode Operation, No LoadV

MODE/SYNC

= 0V, V

ITH

= 0V (Note 5)

V

MODE/SYNC

= 0V, V

ITH

= 0V (Note 5),

I-Grade (Note 2)

Shutdown ModeV

RUN

= 0V

V

RUN

= 0V, I-Grade (Note 2)

●

●

●

●

ELECTRICAL CHARACTERISTICS

CONDITIONSMIN

2.5

2.5

TYPMAXUNITS

V

V

Main Control Loop

550

550

250

250

10

10

1000

1000

500

500

20

20

μA

μA

μA

μA

μA

μA

18711fb

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