Features

n

Wide Input Range: 4V to 36V

One 2.7A and Two 1.8A Output Switching

Regulators with Internal Power Switches

Low Dropout Linear Regulator with External

Transistor

Antiphase Switching Reduces Ripple

Independent Run, Tracking/Soft-Start, and Power

Good Indicators Ease Supply Sequencing

Uses Small Inductors and Ceramic Capacitors

Adjustable, 250kHz to 2.5MHz Switching Frequency,

Synchronizable Over the Full Range

User Programmable Overvoltage and Undervoltage

Lockouts

Thermally Enhanced, 38-Lead TSSOP and

5mm

×

7mm QFN Packages

Automotive

Industrial Supplies

Distributed Power Regulation

DSP Power

LT3507A

Triple Monolithic Step-Down

Regulator with LDO

Description

The

LT

®

3507A

is a triple, current mode, DC/DC converter

with internal power switches and a low dropout regulator.

The switching converters are step-down converters capable

of generating one 2.7A output and two 1.8A outputs. All

three converters are synchronized to a single oscillator.

The 2.7A output runs with opposite phase to the other two

converters, reducing input ripple current. Each regulator

has independent shutdown and soft-start circuits, and

generates a power good signal when its output is in regu-

lation, easing power supply sequencing and interfacing

with microcontrollers and DSPs.

The switching frequency is set with a single resistor yielding

a range of 250kHz to 2.5MHz. The high switching frequency

allows the use of small inductors and capacitors resulting

in a very small triple output supply. The constant switching

frequency, combined with low impedance ceramic capaci-

tors, results in low, predictable output ripple. Frequency

foldback and thermal shutdown provide protection against

fault conditions. The LT3507A provides higher output cur-

rent than available with the LT3507.

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.

applications

n

typical application

5V, 3.3V, 2.5V and 1.8V Step-Down Regulator

V

IN

6V TO 36V

22µF

V

IN1

BOOST1

V

OUT1

1.8V

2.7A

100µF

15k

25.5k

680pF

V

C1

0.22µF BOOST3

SW3

53.6k

22µF

10.2k

25.5k

680pF

V

C3

RT/SYNC

DRIVE

FB4

GND

24.3k

11.5k

2.2µF

3507A TA01a

V

IN2

V

IN3

BOOST2

0.22µF

10µH

V

OUT2

3.3V

33µF 1.5A

34.8k

FB2

680pF

V

C2

BIAS

25.5k

11k

4.7µH

0.22µF

SW1

Start-Up Waveforms—Coincident Tracking

18.7k

FB1

SW2

V

OUT3

1V/DIV

V

OUT2

V

OUT4

V

OUT1

LT3507A

V

OUT2

V

OUT3

5V

1.8A

15µH

FB3

1ms/DIV

V

OUT4

2.5V

0.3A

3507 TA01b

107k

f

SW

= 450kHz

3507afa

For more information

www.linear.com/LT3507A

1

LT3507A

absolute MaxiMuM ratings

(Note 1)

V

IN

Pins...................................................... –0.3V to 36V

BOOST Pins ..............................................................55V

BOOST Above SW .....................................................25V

PGOOD Pins ..............................................................36V

BIAS Pin ....................................................................16V

TRK/SS, V

C

, FB, RT/SYNC Pins...................................6V

RUN, OVLO, UVLO Pins ........................................... V

IN1

DRIVE Pin ...................................................................5V

Operating Junction Temperature Range (Notes 2, 5)

LT3507AE, LT3507AI ......................... –40°C to 125°C

LT3507AH .......................................... –40°C to 150°C

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

Lead Temperature (Soldering, 10 sec)

TSSOP Only ...................................................... 300°C

pin conFiguration

TOP VIEW

BOOST3

TOP VIEW

SW1

SW3

V

IN3

V

IN3

V

IN3

SW1

31 V

IN2

30 V

IN2

29 SW2

28 SW2

27 BOOST2

39

GND

26 TRK/SS4

25 FB4

24 DRIVE

23 V

C2

22 FB2

21 TRK/SS2

20 FB3

13 14 15 16 17 18 19

RT/SYNC

BIAS

TRK/SS3

RUN1

RUN2

RUN3

V

C3

BOOST1

V

IN1

V

IN1

V

INSW

OVLO

UVLO

1

2

3

4

5

6

7

8

9

39

GND

38 SW3

37 BOOST3

36 V

IN2

35 V

IN2

34 NC

33 SW2

32 BOOST2

31 TRK/SS4

30 FB4

29 DRIVE

28 V

C2

27 NC

26 FB2

25 TRK/SS2

24 FB3

23 V

C3

22 TRK/SS3

21 BIAS

20 GND

38 37 36 35 34 33 32

BOOST1 1

V

IN1

2

V

IN1

3

V

INSW

4

OVLO 5

UVLO 6

V

C1

7

TRK/SS1 8

FB1 9

PGOOD1 10

PGOOD2 11

PGOOD3 12

V

C1

10

TRK/SS1 11

FB1 12

PGOOD1 13

PGOOD2 14

PGOOD3 15

RT/SYNC 16

RUN1 17

RUN2 18

RUN3 19

UHF PACKAGE

38-LEAD (5mm

×

7mm) PLASTIC QFN

θ

JA

= 34°C/W

EXPOSED PAD (PIN 39) IS GND, MUST BE SOLDERED TO PCB

FE PACKAGE

38-LEAD PLASTIC TSSOP

θ

JA

= 24°C/W

EXPOSED PAD (PIN 39) IS GND, MUST BE SOLDERED TO PCB

2

3507afa

For more information

www.linear.com/LT3507A

LT3507A

orDer inForMation

LEAD FREE FINISH

TAPE AND REEL

PART MARKING*

PACKAGE DESCRIPTION

TEMPERATURE RANGE

LT3507AEUHF#PBF

LT3507AEUHF#TRPBF

3507A

38-Lead (5mm

×

7mm) Plastic QFN

–40°C to 125°C

LT3507AIUHF#PBF

LT3507AIUHF#TRPBF

3507A

38-Lead (5mm

×

7mm) Plastic QFN

–40°C to 125°C

LT3507AHUHF#PBF

LT3507AHUHF#TRPBF

3507A

38-Lead (5mm

×

7mm) Plastic QFN

–40°C to 150°C

LT3507AEFE#PBF

LT3507AEFE#TRPBF

LT3507AFE

38-Lead Plastic TSSOP

–40°C to 125°C

LT3507AIFE#PBF

LT3507AIFE#TRPBF

LT3507AFE

38-Lead Plastic TSSOP

–40°C to 125°C

LT3507AHFE#PBF

LT3507AHFE#TRPBF

LT3507AFE

38-Lead Plastic TSSOP

–40°C to 150°C

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

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/.

Some packages are available in 500 unit reels through

designated sales channels with #TRMPBF suffix.

electrical characteristics

PARAMETER

Minimum Operating Voltage

Input Quiescent Current

Bias Quiescent Current

Shutdown Current

Reference Voltage Line Regulation

V

C

Source Current

V

C

Sink Current

V

C

Clamp Voltage

Switching Frequency

Switching Phase

Foldback Frequency

Frequency Shift Threshold on FB

RUN Threshold

PGOOD Output Voltage Low

PGOOD Pin Leakage

PGOOD Threshold Offset

Feedback Pin Voltage

Feedback Pin Bias Current

Error Amplifier Transconductance

Error Amplifier Voltage Gain

V

C

Switching Threshold

Switch Leakage Current

Minimum Boost Voltage Above Switch (Note 4)

I

TRK/SS

V

IN1

-V

INSW

Converter 1

V

C1

to Switch Current Gain

The

l

denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T

A

= 25°C. V

IN1

, V

IN2

, V

IN3

= 12V, V

BOOST1

, V

BOOST2

, V

BOOST3

= 17V, unless

otherwise noted. (Notes 2, 7)

CONDITIONS

Internal UVLO on V

IN1

Not Switching, V

BIAS

= 3.3V

Not Switching, V

BIAS

= 3.3V

V

RUN1,2,3

= 0V

5V < V

IN1

< 36V

V

C

= 0.6V

V

C

= 0.6V

R

T

= 40.2k

SW1 to SW2,3, R

T

= 40.2k

V

FB

= 0V, R

T

= 40.2k

l

MIN

TYP

3.8

2

5

0.01

20

30

1.8

MAX

4

3.5

7.5

1

UNITS

V

mA

µA

%/V

µA

V

0.9

180

120

0.4

1

1.1

MHz

Deg

kHz

V

1.5

0.4

400

105

812

–500

V

nA

mV

nA

µS

V/V

V

I

PGOOD

= 200µA

V

PGOOD

= 2V

V

FB

Rising

l

0.2

10

58

788

80

800

–50

330

500

0.9

0.01

1.8

10

2.5

µA

V

µA

V

A/V

3507afa

V

TRK/SS

= 0V

I

VINSW

= 1mA

1.25

0.35

6

For more information

www.linear.com/LT3507A

3

LT3507A

electrical characteristics

PARAMETER

Switch 1 Current Limit (Note 3)

Switch 1 V

CESAT

BOOST1 Operating Current

Converter 2

V

C2

to Switch Current Gain

Switch 2 Current Limit (Note 3)

Switch 2 V

CESAT

BOOST2 Operating Current

Converter 3

V

C3

to Switch Current Gain

Switch 3 Current Limit (Note 3)

Switch 3 V

CESAT

BOOST3 Operating Current

LDO Regulator

Feedback Pin Voltage

Feedback Pin Bias Current

Error Amplifier Voltage Gain

Line Regulation

Load Regulation

DRIVE Output Current Limit

Dropout Voltage, V

IN1

to DRIVE

Dropout Voltage, BIAS to DRIVE

Over/Undervoltage Lockout

Undervoltage Lockout Threshold

Overvoltage Lockout Threhold

Undervoltage Lockout Hysteresis Current

Overvoltage Lockout Hysteresis Current

Input Bias Current (OVLO and UVLO)

V(UVLO) < 1.2V

V(OVLO) > 1.2V

V(OVLO) = 1.0V, V(UVLO) = 1.5V

1.15

7

–7

1.20

10

–10

–100

1.25

13

–13

–200

V

µA

nA

I

DRIVE

= 10mA, V

IN

= 5V

I

DRIVE

= 10mA, V

IN

= 5V

V

IN

from 5V to 36V

I

DRIVE

from 0.1mA to 10mA

l

The

l

denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T

A

= 25°C. V

IN1

, V

IN2

, V

IN3

= 12V, V

BOOST1

, V

BOOST2

, V

BOOST3

= 17V, unless

otherwise noted (Notes 2, 7)

CONDITIONS

Duty Cycle = 15%

I

SW1

= 2A (Note 6)

I

SW1

= 2A

l

MIN

4.3

TYP

5.1

400

40

4.3

MAX

6

600

60

UNITS

A

mV

mA

A/V

Duty Cycle = 15%

I

SW2

= 1.5A (Note 6)

I

SW2

= 1.5A

l

2.7

3.3

350

40

4.3

4

500

60

A

mV

mA

A/V

Duty Cycle = 15%

I

SW3

= 1.5A (Note 6)

I

SW3

= 1.5A

l

2.7

3.3

350

40

4

500

60

812

–500

A

mV

mA

mV

nA

V/V

%/V

%/mA

788

800

–150

1100

0.05

0.005

10

15

1.7

0.5

22.5

2.0

0.8

mA

V

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 LT3507AE is guaranteed to meet performance specifications

from 0°C to 125°C junction temperature. Specifications over the –40°C

to 125°C operating junction temperature range are assured by design,

characterization and correlation with statistical process controls. The

LT3507AI is guaranteed to meet performance specifications from –40°C

to 125°C junction temperature. The LT3507AH is guaranteed over the

full –40°C to 150°C operating junction temperature range. High junction

temperatures degrade operating lifetimes. Operating lifetime is derated at

junction temperatures greater than 125°C.

Note 3:

Current limit is guaranteed by design and/or correlation to static

test. Slope compensation reduces current limit at higher duty cycles.

Note 4:

This is the minimum voltage across the boost capacitor needed to

guarantee full saturation of the internal power switch.

Note 5:

This IC includes overtemperature protection that is intended

to protect the device during momentary overload conditions.

Junction temperature will exceed the maximum operating range when

overtemperature protection is active. Continuous operation above the

specified maximum operating junction temperature may impair device

reliability.

Note 6:

Switch V

CESAT

for the FE package is guaranteed by design and/or

correlation to static test.

Note 7:

Positive currents flow into pins, negative currents flow out of pins.

Minimum and maximum specifications refer to absolute values.

3507afa

4

For more information

www.linear.com/LT3507A

LT3507A

typical perForMance characteristics

90

Efficiency vs Load Current,

Channel 1, V

OUT

= 1.8V

INDUCTOR: NIC NPIM74C4R7MTRF

f

SW

= 450kHz

V

IN

= 6V

EFFICIENCY (%)

V

IN

= 12V

V

IN

= 36V

100

90

80

70

60

50

40

Efficiency vs Load Current,

Channels 2 and 3, V

OUT

= 3.3V

V

IN

= 6V

V

IN

= 12V

V

IN

= 36V

V

CESAT

(V)

Switch V

CESAT

vs Switch Current,

Channels 1, 2 and 3

0.6

0.5

0.4

0.3

0.2

0.1

0

CHANNELS 2 AND 3

CHANNEL 1

T

A

= 25°C

80

EFFICIENCY (%)

70

60

50

40

INDUCTOR: NIC NPIM74C8R2MTRF

f

SW

= 450kHz

0

0.3

0.6

0.9

1.2

I

OUT

(A)

1.5

1.8

0

0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7

I

OUT

(A)

3507A G01

0

0.5

1

3507A G02

1.5

I

SW

(A)

2

2.5

3

3507A G03

BOOST Pin Current vs Switch

Current, Channels 1, 2 and 3

100

90

80

70

I

BOOST

(mA)

50

40

30

20

10

0

0.5

1.0

1.5

I

SW

(A)

2.0

2.5

3.0

CHANNELS 2, 3

CHANNEL 1

V

FB

(mV)

60

805

804

803

V

FB

vs Temperature

2.5

Frequency vs R

T

2.0

FREQUENCY (MHz)

1.5

802

801

800

799

798

797

796

795

–50 –30 –10 30 50 70 90 110 130 150

TEMPERATURE (°C)

3507A G05

1.0

0.5

0

3507A G04

20 40 60 80 100 120 140 160 180 200

R

T

(k )

3507A G06

Frequency vs Temperature

0.5

1200

1000

FRERQUENCY (kHz)

800

600

400

200

0

Frequency vs V

FB

(Foldback)

R

T

= 40.2k

T

A

= 25°C

1.30

I

TRK/SS

vs Temperature

FREQUENCY DEVIATION (%)

0.0

1.28

–1.0

I

TRK/SS

(µA)

0

0.2

0.4

0.6

V

FB

(V)

0.8

1

3507A G08

–0.5

1.26

1.24

–1.5

1.22

–2.0

–50 –30 –10 30 50 70 90 110 130 150

TEMPERATURE (°C)

3507A G07

1.20

–50 –30 –10 30 50 70 90 110 130 150

TEMPERATURE (°C)

3507A G09

3507afa

For more information

www.linear.com/LT3507A

5

参数名称	属性值
欧盟限制某些有害物质的使用	Compliant
ECCN (US)	EAR99
Part Status	Active
HTS	8542.39.00.01
类型 Type	Step Down
输出类型 Output Type	Adjustable
Switching Frequency (kHz)	250 to 2500
Switching Regulator	Yes
Number of Outputs	3
Output Voltage (V)	0.8 to 32.4
Maximum Output Current (A)	1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|2.7\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8\|1.8
Minimum Input Voltage (V)	4
Maximum Input Voltage (V)	36
Operating Supply Voltage (V)	4 to 36
Typical Switch Current (A)	3.3\|5.1\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3\|3.3
Typical Quiescent Current (uA)	2000
Minimum Operating Temperature (°C)	-40
Maximum Operating Temperature (°C)	150
Supplier Temperature Grade	Automotive
系列 Packaging	Tape and Reel
Pin Count	38
Standard Package Name	QFN
Supplier Package	QFN EP
Mounting	Surface Mount
Package Height	0.75(Max)
Package Length	7
Package Width	5
PCB changed	38
Lead Shape	No Lead

LT3507AHUHF#TRPBF

LT3507AHUHF#TRPBF概述

LT3507AHUHF#TRPBF规格参数

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