FEATURES

n

Dual Buck Plus Single Boost Synchronous Controllers

Wide Bias Input Voltage Range: 4.5V to 38V

Outputs Remain in Regulation Through Cold Crank

Down to a 2.5V Input Supply Voltage

Buck Output Voltage Range: 0.8V ≤ V

OUT

≤ 24V

Boost Output Voltage Up to 60V

Low Operating I

Q

: 28μA (One Channel On)

R

SENSE

or DCR Current Sensing

100% Duty Cycle for Boost Synchronous MOSFET

Even in Burst Mode

®

Operation

Phase-Lockable Frequency (320kHz to 2.25MHz)

Programmable Fixed Frequency (320kHz to 2.25MHz)

Very Low Buck Dropout Operation: 98% Duty Cycle

Small 38-Lead 5mm

×

7mm QFN Package

Automotive Always-On and Start-Stop Systems

Battery Operated Digital Devices

Distributed DC Power Systems

Multioutput Buck-Boost Applications

LTC7815

Low I

Q

, 2.25MHz,

Triple Output, Buck/Buck/Boost

Synchronous Controller

DESCRIPTION

The

LTC

®

7815

is a high performance triple output (buck/

buck/boost) synchronous DC/DC switching regulator con-

troller that drives all N-channel power MOSFET stages.

Constant frequency current mode architecture allows a

phase-lockable switching frequency of up to 2.25MHz.

The LTC7815 operates from a wide 4.5V to 38V input

supply range. When biased from the output of the boost

converter or another auxiliary supply, the LTC7815 can

operate from an input supply as low as 2.5V after start-up.

The 28μA no-load quiescent current extends operating

runtime in battery powered systems. OPTI-LOOP com-

pensation allows the transient response to be optimized

over a wide range of output capacitance and ESR values.

The LTC7815 features a precision 0.8V reference for the

bucks, 1.2V reference for the boost and a power good

output indicator. The PLLIN/MODE pin selects among

Burst Mode operation, pulse-skipping mode, or continu-

ous inductor current mode at light loads.

All registered trademarks and trademarks are the property of their respective owners. Protected

by U.S. Patents including 5481178, 5705919, 5929620, 6144194, 6177787, 6580258.

APPLICATIONS

n

TYPICAL APPLICATION

V

OUT3

REGULATED AT 10V WHEN V

IN

< 10V

FOLLOWS V

IN

WHEN V

IN

> 10V

+

68µF

10µF

×5

499k

68.1k

V

FB3

V

BIAS

TG1

0.33µH

V

OUT1

5V

7A

Efficiency and Power Loss vs

Output Current

100

3mΩ

V

IN

= 12V

90 V

OUT1

= 5V

80

70

60

50

40

30

20

10

f = 2.1MHz

Burst Mode OPERATION

BURST LOSS

0.001

0.01

0.1

LOAD CURRENT (A)

1

10

7815 TA01b

10k

EFFICIENCY (%)

V

IN

2.5V TO 28V

(START-UP ABOVE 5V)

3mΩ

0.16µH

TG3

SW3

BG3

SENSE3

–

SENSE3

+

INTV

CC

4.7µF

BOOST1, 2, 3

LTC7815

SW1

BG1

+

1k

POWER LOSS (mW)

+

220µF

100

SENSE1

–

V

FB1

68.1k

EXTV

CC

TG2

SW2

BG2

SENSE2

+

SENSE2

–

V

FB2

68.1k

V

OUT1

0.33µH

10

10µF

×2

357k

C

OUT1

47µF

×2

1

SW1, 2, 3

0.1µF

I

TH1, 2, 3

3mΩ

V

OUT2

3.3V

10A

0

0.0001

0.1

0.1µF

TRACK/SS1, 2

SS3

RUN1

RUN2

RUN3

PGND

210k

C

OUT2

33µF

×2

FREQ

SGND

7815 TA01a

100k

7815f

For more information

www.linear.com/LTC7815

1

LTC7815

ABSOLUTE MAXIMUM RATINGS

(Note 1)

Bias Input Supply Voltage (V

BIAS

) .............. –0.3V to 40V

Buck Top Side Driver Voltages

(BOOST1, BOOST2) ............................. –0.3V to 46V

Boost Top Side Driver Voltages

(BOOST3) ............................................ –0.3V to 71V

Buck Switch Voltage (SW1, SW2) ................ –5V to 40V

Boost Switch Voltage (SW3) ........................ –5V to 65V

INTV

CC

, (BOOST1–SW1),

(BOOST2–SW2), (BOOST3–SW3) ........... –0.3V to 6V

BG1, BG2, BG3, TG1, TG2, TG3 ...................... (Note 8)

RUN1, RUN2, RUN3 .................................... –0.3V to 8V

Maximum Current Sourced Into Pin

from Source >8V ..............................................100µA

SENSE1

+

, SENSE2

+

, SENSE1

–

SENSE2

–

Voltages ................................. –0.3V to 28V

SENSE3

+

, SENSE3

–

Voltages ..................... –0.3V to 40V

FREQ Voltages ......................................–0.3V to INTV

CC

EXTV

CC

...................................................... –0.3V to 14V

I

TH1

, I

TH2

, I

TH3

, V

FB1

, V

FB2

, V

FB3

Voltages.... –0.3V to 6V

PLLIN/MODE, PGOOD1, OV3 Voltages ........ –0.3V to 6V

TRACK/SS1, TRACK/SS2, SS3 Voltages ..... –0.3V to 6V

Operating Junction Temperature Range (Notes 2, 3)

LTC7815E, LTC7815I .......................... –40°C to 125°C

LTC7815H .......................................... –40°C to 150°C

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

PIN CONFIGURATION

TOP VIEW

TRACK/SS1

SENSE1

–

SENSE1

+

PGOOD1

V

FB1

I

TH1

38 37 36 35 34 33 32

FREQ 1

PLLIN/MODE 2

SS3 3

SENSE3

+

TG1

31 SW1

30 BOOST1

29 BG1

28 SW3

27 TG3

26 BOOST3

25 BG3

24 V

BIAS

23 EXTV

CC

22 INTV

CC

21 BG2

20 BOOST2

SW2

4

5

39

PGND

SENSE3

–

V

FB3

6

I

TH3

7

SGND 8

RUN1 9

RUN2 10

RUN3 11

SENSE2 12

–

13 14 15 16 17 18 19

V

FB2

I

TH2

TRACK/SS2

OV3

SENSE2

+

TG2

UHF PACKAGE

38-LEAD (5mm

×

7mm) PLASTIC QFN

T

JMAX

= 150°C,

q

JA

= 34.7°C/W,

q

JC

= 2°C/W

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

7815f

2

For more information

www.linear.com/LTC7815

LTC7815

ORDER INFORMATION

LEAD FREE FINISH

LTC7815EUHF#PBF

LTC7815IUHF#PBF

LTC7815HUHF#PBF

TAPE AND REEL

LTC7815EUHF#TRPBF

LTC7815IUHF#TRPBF

LTC7815HUHF#TRPBF

http://www.linear.com/product/LTC7815#orderinfo

PART MARKING*

7815

PACKAGE DESCRIPTION

38-Lead (5mm × 7mm) Plastic QFN

TEMPERATURE RANGE

–40°C to 125°C

–40°C to 150°C

Consult ADI 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.

The

l

denotes the specifications which apply over the specified operating

junction temperature range, otherwise specifications are at T

A

= 25°C (Notes 2, 4). V

BIAS

= 12V, V

RUN1,2,3

= 5V, EXTV

CC

= 0V unless

otherwise noted.

SYMBOL

V

BIAS

V

FB1,2

PARAMETER

Bias Input Supply Operating Voltage

Range

Buck Regulated Feedback Voltage

(Note 4); I

TH1,2

Voltage = 1.2V

0°C to 85°C, All Grades

LTC7815E, LTC7815I

LTC7815H

(Note 4); I

TH3

Voltage = 1.2V

0°C to 85°C, All Grades

LTC7815E, LTC7815I

LTC7815H

(Note 4)

(Note 4); V

IN

= 4.5V to 38V

(Note 4)

Measured in Servo Loop;

∆I

TH

Voltage = 1.2V to 0.7V

Measured in Servo Loop;

∆I

TH

Voltage = 1.2V to 2V

g

m1,2,3

Transconductance Amplifier g

m

(Note 4); I

TH1,2,3

= 1.2V;

Sink/Source 5µA

l

ELECTRICAL CHARACTERISTICS

CONDITIONS

MIN

4.5

TYP

MAX

38

UNITS

V

l

0.792

0.788

0.786

1.183

1.181

1.176

0.800

1.200

–2

0.002

0.01

–0.01

2

0.808

0.812

1.214

1.218

±50

0.02

0.1

–0.1

V

nA

%/V

%

mmho

V

FB3

Boost Regulated Feedback Voltage

l

I

FB1,2,3

V

REFLNREG

V

LOADREG

Feedback Current

Reference Voltage Line Regulation

Output Voltage Load Regulation

7815f

For more information

www.linear.com/LTC7815

3

LTC7815

ELECTRICAL CHARACTERISTICS

SYMBOL

I

Q

PARAMETER

Input DC Supply Current

Pulse-Skipping or

Forced Continuous Mode

(One Channel On)

The

l

denotes the specifications which apply over the specified operating

junction temperature range, otherwise specifications are at T

A

= 25°C (Notes 2, 4). V

BIAS

= 12V, V

RUN1,2,3

= 5V, EXTV

CC

= 0V unless

otherwise noted.

CONDITIONS

(Note 5)

RUN1 = 5V and RUN2,3 = 0V or

RUN2 = 5V and RUN1,3 = 0V or

RUN3 = 5V and RUN1,2 = 0V

V

FB1, 2

ON = 0.83V (No Load)

V

FB3

= 1.25V

RUN1,2,3 = 5V,

V

FB1,2

= 0.83V (No Load)

V

FB3

= 1.25V

RUN1 = 5V and RUN2,3 = 0V or

RUN2 = 5V and RUN1,3 = 0V

V

FB,ON

= 0.83V (No Load)

RUN3 = 5V and RUN1,2 = 0V

V

FB3

= 1.25V

RUN1 = 5V and RUN2 = 0V or

RUN2 = 5V and RUN1 = 0V

RUN3 = 5V

V

FB1,2

= 0.83V (No Load)

V

FB3

= 1.25V

RUN1,2,3 = 5V,

V

FB1,2

= 0.83V (No Load)

V

FB3

= 1.25V

RUN1,2,3 = 0V

INTV

CC

Ramping Up

INTV

CC

Ramping Down

V

OVL1,2

I

SENSE1,2

+

I

SENSE3

+

I

SENSE1,2

–

I

SENSE3

–

DF

MAX,TG

DF

MAX,BG

I

TRACK/SS1,2

I

SS3

V

RUN1

ON

V

RUN2,3

ON

V

RUN1,2,3

Hyst

Buck Feedback Overvoltage Protection

SENSE

+

Pin Current

SENSE

+

Pin Current

SENSE

–

Pin Current

SENSE

–

Pin Current

Maximum Duty Factor for TG

Maximum Duty Factor for BG

Soft-Start Charge Current

RUN1 Pin Threshold

RUN2,3 Pin Threshold

RUN Pin Hysteresis

V

FB1,2

= 0.7V, V

SENSE1,2

– = 3.3V

V

FB1,2,3

= 1.1V, V

SENSE3

+ = 12V

l

MIN

TYP

1.5

MAX

UNITS

mA

Pulse-Skipping or

Forced Continuous Mode

(All Channels On)

Sleep Mode

(One Channel On, Buck)

Sleep Mode

(One Channel On, Boost)

Sleep Mode

(Buck and Boost Channel On)

3

mA

28

35

33

40

48

59

53

46

59

µA

Sleep Mode

(All Three Channels On)

Shutdown

UVLO

Undervoltage Lockout

38

56

µA

10

4.15

3.5

7

3.8

10

20

4.5

4.0

13

±1

µA

V

%

µA

Measured at V

FB1,2

Relative to

Regulated V

FB1,2

Bucks (Channels 1 and 2) V

OUT

= 3.3V

Boost (Channel 3)

Bucks (Channels 1 and 2)

V

OUT

= 3.3V

V

OUT1,2

> V

INTVCC

+ 0.5V

Boost (Channel 3)

V

SENSE3

+, V

SENSE3

– = 12V

Bucks (Channels 1,2) in Dropout, FREQ = 0V

Boost (Channel 3) in Overvoltage

Bucks (Channels 1,2) in Overvoltage

Boost (Channel 3)

V

TRACK/SS1,2

= 0V

V

SS3

= 0V

V

RUN1

Rising

V

RUN2,3

Rising

l

170

±2

±1

97

98

100

90

3

1.18

1.21

43

2.5

5

1.24

1.27

70

50

57

38

8

1.32

1.33

700

µA

%

µA

V

mV

V

SENSE1,2,3(MAX)

Maximum Current Sense Threshold

V

SENSE3(CM)

SENSE3 Pins Common Mode Range

(BOOST Converter Input Supply Voltage)

7815f

4

For more information

www.linear.com/LTC7815

LTC7815

ELECTRICAL CHARACTERISTICS

SYMBOL

Gate Driver

TG1,2

BG1,2

TG3

BG3

Pull-Up On-Resistance

Pull-Down On-Resistance

Pull-Up On-Resistance

Pull-Down On-Resistance

Pull-Up On-Resistance

Pull-Down On-Resistance

Pull-Up On-Resistance

Pull-Down On-Resistance

TG Transition Time:

Rise Time

Fall Time

BG Transition Time:

Rise Time

Fall Time

Top Gate Off to Bottom Gate On Delay

Synchronous Switch-On Delay Time

Bottom Gate Off to Top Gate On Delay

Top Switch-On Delay Time

Buck Minimum On-Time

Boost Minimum On-Time

Internal V

CC

Voltage

INTV

CC

Load Regulation

Internal V

CC

Voltage

INTV

CC

Load Regulation

EXTV

CC

Switchover Voltage

EXTV

CC

Hysteresis

Programmable Frequency

Low Fixed Frequency

High Fixed Frequency

Synchronizable Frequency

PLLIN/MODE Input High Level

PLLIN/MODE Input Low Level

R

FREQ

= 25k; PLLIN/MODE = DC Voltage

R

FREQ

= 65k; PLLIN/MODE = DC Voltage

R

FREQ

= 100k; PLLIN/MODE = DC Voltage

V

FREQ

= 0V PLLIN/MODE = DC Voltage

V

FREQ

= INTV

CC

; PLLIN/MODE = DC Voltage

PLLIN/MODE = External Clock

l

The

l

denotes the specifications which apply over the specified operating

junction temperature range, otherwise specifications are at T

A

= 25°C (Notes 2, 4). V

BIAS

= 12V, V

RUN1,2,3

= 5V, EXTV

CC

= 0V unless

otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

2.5

1.5

2.4

1.1

1.2

1.0

1.2

1.0

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

C

LOAD

= 3300pF Each Driver Bucks (Channels 1, 2)

Boost (Channel 3)

C

LOAD

= 3300pF Each Driver Bucks (Channels 1, 2)

Boost (Channel 3)

(Note 7)

6V < V

BIAS

< 38V, V

EXTVCC

= 0V, I

INTVCC

= 0mA

I

CC

= 0mA to 100mA, V

EXTVCC

= 0V

6V < V

EXTVCC

< 13V, I

INTVCC

= 0mA

I

CC

= 0mA to 100mA, V

EXTVCC

= 8.5V

EXTV

CC

Ramping Positive

4.5

5.0

25

16

28

13

25

30

20

45

70

5.4

0.8

5.4

0.8

4.7

200

0.25

1.75

0.77

1.2

0.32

2.5

0.5

0.32

1.18

2.1

0.94

1.44

2.4

1.13

1.75

2.25

0.37

5.6

2.5

5.6

2.5

MAX

UNITS

Ω

ns

V

%

V

%

V

mV

MHz

V

TG1,2,3 t

r

TG1,2,3 t

f

BG1,2,3 t

r

BG1,2,3 t

f

TG/BG t

1D

BG/TG t

1D

t

ON(MIN)1,2

t

ON(MIN)3

V

INTVCCVBIAS

V

LDOVBIAS

V

INTVCCEXT

V

LDOEXT

V

EXTVCC

V

LDOHYS

f

25k

f

65k

f

100k

f

LOW

f

HIGH

f

SYNC

PLLIN V

IH

PLLIN V

IL

INTV

CC

Linear Regulator

Oscillator and Phase-Locked Loop

7815f

For more information

www.linear.com/LTC7815

5

参数名称	属性值
厂商名称	ADI(亚德诺半导体)
产品种类	开关控制器
拓扑结构	Boost, Buck
输出端数量	3 Output
开关频率	320 kHz to 2.25 MHz
占空比 - 最大	100 %
输入电压	4.5 V to 38 V
输出电压	0.8 V to 60 V
输出电流	25 A
最小工作温度	- 40 C
最大工作温度	+ 125 C
安装风格	SMD/SMT
封装 / 箱体	QFN-38
封装	Reel
绝缘	Non-Isolated
产品	Switching Controllers
系列	LTC7815
工作电源电压	4.5 V to 38 V
工厂包装数量	2500

LTC7815IUHF#TRPBF

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