LTC1700_ 查看數據表（PDF） - Linear Technology

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LTC1700_

High Input Voltage, Current Mode Boost, Flyback and SEPIC Controller

Linear Technology 

LTC1871-7

High Input Voltage,

Current Mode Boost,

Flyback and SEPIC Controller

FEATURES

s Optimized for High Input Voltage Applications

s Wide Chip Supply Voltage Range: 6V to 36V

s Internal 7V Low Dropout Voltage Regulator

Optimized for 6V-Rated MOSFETs

s Current Mode Control Provides Excellent

Transient Response

s High Maximum Duty Cycle (92% Typ)

s ±2% RUN Pin Threshold with 100mV Hysteresis

s ±1% Internal Voltage Reference

s Micropower Shutdown: IQ = 10µA

s Programmable Operating Frequency

(50kHz to 1MHz) with One External Resistor

s Synchronizable to an External Clock Up to 1.3 × fOSC

s User-Controlled Pulse Skip or Burst Mode® Operation

s Output Overvoltage Protection

s Can be Used in a No RSENSETM Mode for VDS < 36V

s Small 10-Lead MUSOP Package

APPLICATIO S

s Telecom Power Supplies

s 42V Automotive Systems

s 24V Industrial Controls

s IP Phone Power Supplies

DESCRIPTIO

The LTC®1871-7 is a current mode, boost, flyback and

SEPIC controller optimized for driving 6V-rated MOSFETs

in high voltage applications. The LTC1871-7 works equally

well in low or high power applications and requires few

components to provide a complete power supply solu-

tion. The switching 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.

Burst Mode operation at light loads, a low minimum

operating supply voltage of 6V and a low shutdown

quiescent current of 10µA make the LTC1871-7 well

suited for battery-operated systems. For applications

requiring constant frequency operation, Burst Mode op-

eration can be defeated using the MODE/SYNC pin. The

LTC1871-7 is available in the 10-lead MSOP package.

PARAMETER

INTVCC

INTVCC UV+

INTVCC UV–

LTC1871-7

7.0V

5.6V

4.6V

LTC1871

5.2V

2.1V

1.9V

, LTC and LT are registered trademarks of Linear Technology Corporation.

Burst Mode is a registered trademark of Linear Technology Corporation.

No RSENSE is a trademark of Linear Technology Corporation.

TYPICAL APPLICATIO

VIN

36V TO 72V

26.7k

604k

2.2µF

100V

X7R

100k

D1

9.1V

Q1

FMMT625

10Ω

D3

10BQ060

3:1

T1

VP1-0076

47µF

16V

X5R

VOUT

12V

0.4A

2.2nF

3.4k

RUN

SENSE

ITH

VIN

LTC1871-7

D2

4148

12.4k

110k

120k

FB

FREQ

INTVCC

GATE

MODE/SYNC GND

4.7µF

X5R

M1

FDC2512

0.1µF

X5R

0.12Ω

18717 F01

Figure 1. Small, Nonisolated 12V Flyback Telecom Housekeeping Supply

18717f

1

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