LTC3642IMS8E-5-TRPBF,LTC3642IMS8E-5-TRPBF pdf中文资料,LTC3642IMS8E-5-TRPBF引脚图,LTC3642IMS8E-5-TRPBF电路-Datasheet-电子工程世界

FEATURES

n

LTC3642

High Efﬁciency, High Voltage

50mA Synchronous

Step-Down Converter

DESCRIPTION

The LTC

®

3642 is a high efﬁciency step-down DC/DC

converter with internal high side and synchronous power

switches that draws only 12μA typical DC supply current

at no load while maintaining output voltage regulation.

The LTC3642 can supply up to 50mA load current and

features a programmable peak current limit that provides

a simple method for optimizing efﬁciency in lower current

applications. The LTC3642’s combination of Burst Mode

®

operation, integrated power switches, low quiescent cur-

rent, and programmable peak current limit provides high

efﬁciency over a broad range of load currents.

With its wide 4.5V to 45V input range and internal

overvoltage monitor capable of protecting the part through

60V surges, the LTC3642 is a robust converter suited for

regulating a wide variety of power sources. Additionally,

the LTC3642 includes a precise run threshold and soft-start

feature to guarantee that the power system start-up is

well-controlled in any environment.

The LTC3642 is available in the thermally enhanced

3mm

×

3mm DFN and MS8E packages.

L,

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

All other trademarks are the property of their respective owners.

Wide Input Voltage Range: 4.5V to 45V

Tolerant of 60V Input Transients

Internal High Side and Low Side Power Switches

No Compensation Required

50mA Output Current

Low Dropout Operation: 100% Duty Cycle

Low Quiescent Current: 12μA

0.8V Feedback Voltage Reference

Adjustable Peak Current Limit

Internal and External Soft-Start

Precise RUN Pin Threshold with Adjustable

Hysteresis

3.3V, 5V and Adjustable Output Versions

Only Three External Components Required for Fixed

Output Versions

Low Proﬁle (0.75mm) 3mm

×

3mm DFN and

Thermally-Enhanced MS8E Packages

APPLICATIONS

n

4mA to 20mA Current Loops

Industrial Control Supplies

Distributed Power Systems

Portable Instruments

Battery-Operated Devices

Automotive Power Systems

TYPICAL APPLICATION

5V, 50mA Step-Down Converter

V

IN

5V TO 45V

1μF

V

IN

SW

LTC3642-5

RUN

V

OUT

SS

HYST

I

SET

GND

3642 TA01a

Efﬁciency and Power Loss vs Load Current

100

95

EFFICIENCY

90

V

OUT

5V

10μF 50mA

EFFICIENCY (%)

POWER LOSS (mW)

V

IN

= 10V

100

150μH

85

80

75

70

65

0.1

POWER LOSS

10

1

10

LOAD CURRENT (mA)

0.1

100

3642 TA01b

3642f

1

LTC3642

ABSOLUTE MAXIMUM RATINGS

(Note 1)

V

IN

Supply Voltage ..................................... –0.3V to 60V

SW Voltage (DC) ............................–0.3V to (V

IN

+ 0.3V)

RUN Voltage .............................................. –0.3V to 60V

V

FB

/V

OUT

, HYST, I

SET

, SS Voltages ................ –0.3V to 6V

Operating Junction Temperature Range

(Note 2).................................................. –40°C to 125°C

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

Lead Temperature (Soldering, 10 sec)

MS8E ................................................................ 300°C

PIN CONFIGURATION

TOP VIEW

SW

V

IN

I

SET

SS

1

2

3

4

8

7

6

5

GND

HYST

V

OUT

/V

FB

RUN

SW 1

V

IN

2

I

SET

3

SS 4

9

8

7

6

5

GND

HYST

V

OUT

/V

FB

RUN

9

MS8E PACKAGE

8-LEAD PLASTIC MSOP

T

JMAX

= 125°C,

θ

JA

= 40°C/W,

θ

JC

= 5°-10°C/W

EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB

DD PACKAGE

8-LEAD (3mm 3mm) PLASTIC DFN

T

JMAX

= 125°C,

θ

JA

= 43°C/W,

θ

JC

= 3°C/W

EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

LTC3642EMS8E#PBF

LTC3642EMS8E-3.3#PBF

LTC3642EMS8E-5#PBF

LTC3642IMS8E#PBF

LTC3642IMS8E-3.3E#PBF

LTC3642IMS8E-5#PBF

LTC3642EDD#PBF

LTC3642EDD-3.3#PBF

LTC3642EDD-5#PBF

LTC3642IDD#PBF

LTC3642IDD-3.3#PBF

LTC3642IDD-5#PBF

TAPE AND REEL

LTC3642EMS8E#TRPBF

LTC3642EMS8E-3.3#TRPBF

LTC3642EMS8E-5#TRPBF

LTC3642IMS8E#TRPBF

LTC3642IMS8E-3.3#TRPBF

LTC3642IMS8E-5#TRPBF

LTC3642EDD#TRPBF

LTC3642EDD-3.3#TRPBF

LTC3642EDD-5#TRPBF

LTC3642IDD#TRPBF

LTC3642IDD-3.3#TRPBF

LTC3642IDD-5#TRPBF

PART MARKING*

PACKAGE DESCRIPTION

8-Lead Plastic MSOP

8-Lead (3mm

×

3mm) Plastic DFN

8-Lead (3mm

×

3mm) Plastic DFN

8-Lead (3mm

×

3mm) Plastic DFN

8-Lead (3mm

×

3mm) Plastic DFN

8-Lead (3mm

×

3mm) Plastic DFN

8-Lead (3mm

×

3mm) Plastic DFN

TEMPERATURE RANGE

–40°C to 125°C

LTDTH

LTDYN

LTDYQ

LTDTH

LTDYN

LTDYQ

LDTJ

LDYM

LDYP

LDTJ

LDYM

LDYP

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container.

Consult LTC Marketing for information on non-standard lead based ﬁnish parts.

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

http://www.linear.com/leadfree/

For more information on tape and reel speciﬁcations, go to:

http://www.linear.com/tapeandreel/

3642f

2

LTC3642

ELECTRICAL CHARACTERISTICS

SYMBOL

V

IN

UVLO

PARAMETER

Input Voltage Operating Range

V

IN

Undervoltage Lockout

V

IN

Rising

V

IN

Falling

Hysteresis

V

IN

Rising

V

IN

Falling

Hysteresis

l

The

l

denotes the speciﬁcations which apply over the full operating

junction temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= 10V, unless otherwise noted.

CONDITIONS

MIN

4.5

3.80

3.75

47

45

4.15

4.00

150

50

48

2

125

12

3

3.277

3.257

4.965

4.935

0.792

3.5

-10

3.310

3.290

5.015

4.985

0.800

5

0

0.001

TYP

MAX

45

4.40

4.25

52

50

UNITS

V

mV

V

μA

V

mV

nA

%/V

Input Supply (V

IN

)

OVLO

V

IN

Overvoltage Lockout

I

Q

DC Supply Current (Note 3)

Active Mode

Sleep Mode

Shutdown Mode

Output Voltage Trip Thresholds

V

RUN

= 0V

LTC3642-3.3V, V

OUT

Rising

LTC3642-3.3V, V

OUT

Falling

LTC3642-5V, V

OUT

Rising

LTC3642-5V, V

OUT

Falling

l

220

22

6

3.343

3.323

5.065

5.035

0.808

6.5

10

Output Supply (V

OUT

/V

FB

)

V

OUT

V

FB

V

HYST

I

FB

ΔV

LINEREG

Operation

V

RUN

Feedback Comparator Trip Voltage

Feedback Comparator Hysteresis

Feedback Pin Current

Feedback Voltage Line Regulation

V

FB

Rising

Adjustable Output Version, V

FB

= 1V

V

IN

= 4.5V to 45V

LTC3642-5, V

IN

= 6V to 45V

RUN Rising

RUN Falling

Hysteresis

RUN = 1.3V

RUN < 1V, I

HYST

= 1mA

V

HYST

= 1.3V

V

SS

< 1.5V

SS Pin Floating

I

SET

Floating

500k Resistor from I

SET

to GND

I

SET

Shorted to GND

I

SW

= –25mA

I

SW

= 25mA

Run Pin Threshold

1.17

1.06

–10

4.5

l

1.21

1.10

110

0

0.07

0

5.5

0.75

115

55

25

3.0

1.5

1.25

1.14

10

0.1

10

6.5

130

32

V

mV

nA

V

nA

μA

ms

mA

Ω

I

RUN

V

HYSTL

I

HYST

I

SS

t

INTSS

I

PEAK

Run Pin Leakage Current

Hysteresis Pin Voltage Low

Hysteresis Pin Leakage Current

Soft-Start Pin Pull-Up Current

Internal Soft-Start Time

Peak Current Trip Threshold

100

20

R

ON

Power Switch On-Resistance

Top Switch

Bottom Switch

Note 1:

Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2:

The LTC3642E is guaranteed to meet speciﬁcations from 0°C

to 85°C with speciﬁcations over the –40°C to 125°C operating junction

temperature range assured by design, characterization and correlation

with statistical process controls. The LTC3642I is guaranteed to meet

speciﬁcations from –40°C to 125°C.

T

J

is calculated from the ambient temperature T

A

and power dissipation P

D

according to the following formula:

T

J

= T

A

+ (P

D

•

θ

JA

°C/W)

Note 3:

Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. See Applications Information.

3642f

3

LTC3642

TYPICAL PERFORMANCE CHARACTERISTICS

Efﬁciency vs Load Current

100

FIGURE 10 CIRCUIT

95 I

SET

OPEN

V

OUT

= 5V

90

EFFICIENCY (%)

85

80

75

70

65

60

0.1

1

10

LOAD CURRENT (mA)

100

3642 G01

Line Regulation

0.30

I

LOAD

= 25mA

FIGURE 10 CIRCUIT

OUTPUT VOLTAGE (V)

5.05

5.04

5.03

5.02

5.01

5.00

4.99

4.98

4.97

4.96

–0.30

5

10

15

20 25 30 35

V

IN

VOLTAGE (V)

40

45

4.95

0.20

V

OUT

/V

OUT

(%)

0.10

0

Load Regulation

V

IN

= 10V

FIGURE 10 CIRCUIT

I

SET

OPEN

V

IN

= 10V

V

IN

= 15V

V

IN

= 45V

V

IN

= 24V

V

IN

= 36V

–0.10

–0.20

0

10

30

40

20

LOAD CURRENT (mA)

50

3642 G03

3642 G02

Feedback Comparator Voltage vs

Temperature

FEEDBACK COMPARATOR TRIP VOLTAGE (V)

V

IN

= 10V

FEEDBACK COMPARATOR HYSTERESIS (mV)

0.801

5.6

5.4

5.2

5.0

4.8

4.6

Feedback Comparator Hysteresis

vs Temperature

PEAK CURRENT TRIP THRESHOLD (mA)

V

IN

= 10V

Peak Current Trip Theshold vs

Temperature

130

V = 10V

120

IN

110

100

90

80

70

60

50

40

30

20

10

0

–40

–10

I

SET

OPEN

0.800

R

ISET

= 500k

0.799

I

SET

= GND

0.798

–40

–10

20

50

80

TEMPERATURE (°C)

110

3642 G04

4.4

–40

–10

20

50

80

TEMPERATURE (°C)

110

3642 G05

20

50

80

TEMPERATURE (°C)

110

3642 G06

Peak Current Trip Threshold

vs R

ISET

120

PEAK CURRENT TRIP THRESHOLD (mA)

110

100

90

80

70

60

50

40

30

20

10

0

200

400

600

800

R

SET

(kΩ)

1000

1200

0

V

IN

= 10V

V

IN

SUPPLY CURRENT (μA)

14

12

10

8

6

4

2

Quiescent Supply Current vs

Input Voltage

14

12

V

IN

SUPPLY CURRENT (μA)

SLEEP

Quiescent Supply Current vs

Temperature

V

IN

= 10V

SLEEP

10

8

6

4

2

0

–40

SHUTDOWN

5

15

25

35

V

IN

VOLTAGE (V)

45

3642 G08

–10

20

50

80

TEMPERATURE (°C)

110

3642 G09

3642 G07

3642f

4

LTC3642

TYPICAL PERFORMANCE CHARACTERISTICS

Switch On-Resistance vs

Input Voltage

4.5

4.0

SWITCH ON-RESISTANCE (Ω)

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0

10

30

20

V

IN

VOLTAGE (V)

40

50

3642 G10

Switch On-Resistance vs

Temperature

5

V

IN

= 10V

SWITCH LEAKAGE CURRENT (μA)

0.6

0.5

0.4

Switch Leakage Current vs

Temperature

V

IN

= 45V

4

TOP

3

BOTTOM

TOP

SW = 0V

0.3

0.2

SW = 45V

0.1

0

–40

BOTTOM

2

1

0

–40

–10

50

80

20

TEMPERATURE (°C)

110

3642 G11

–10

20

50

80

TEMPERATURE (°C)

110

3642 G12

Efﬁciency vs Input Voltage

95

90

EFFICIENCY (%)

85

I

LOAD

= 10mA

80

I

LOAD

= 1mA

75

70

65

10

15

20

25

30

35

INPUT VOLTAGE (V)

40

45

RUN COMPARATOR THRESHOLD (V)

FIGURE 10 CIRCUIT

I

SET

OPEN

I

LOAD

= 50mA

1.30

1.25

1.20

1.15

Run Comparator Thresholds vs

Temperature

1.20

INTERNAL SOFT-START TIME (ms)

110

3642 G14

Internal Soft-Start Time vs

Temperature

RISING

1.15

1.10

1.05

1.00

0.95

0.90

–40

FALLING

1.10

1.05

1.00

–40

–10

20

50

80

TEMPERATURE (°C)

–10

20

50

80

TEMPERATURE (°C)

110

3642 G15

3642 G13

Soft-Start Waveforms

OUTPUT

VOLTAGE

1V/DIV

OUTPUT

VOLTAGE

50mV/DIV

SWITCH

VOLTAGE

5V/DIV

INDUCTOR

CURRENT

50mA/DIV

V

IN

= 10V

500μs/DIV

C

SS

= 0.047μF

I

SET

OPEN

FIGURE 10 CIRCUIT

4632 G16

Operating Waveforms

OUTPUT

VOLTAGE

25mV/DIV

Load Step Transient Response

INDUCTOR

CURRENT

50mA/DIV

LOAD

CURRENT

25mA/DIV

V

IN

= 10V

10μs/DIV

I

SET

OPEN

FIGURE 10 CIRCUIT

4632 G17

V

IN

= 10V

1ms/DIV

I

SET

OPEN

FIGURE 10 CIRCUIT

4632 G18

3642f

5

LTC3642IMS8E-5-TRPBF

LTC3642IMS8E-5-TRPBF概述

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