FEATURES

n

LTC3853

Triple Output,

Multiphase Synchronous

Step-Down Controller

DESCRIPTION

The LTC

®

3853 is a high performance triple output step-

down switching regulator controller that drives all N-chan-

nel synchronous power MOSFET stages. Power loss and

supply noise are minimized by operating the output stages

out of phase. The part can be conﬁgured as a dual phase

controller plus a single phase controller if needed. The

part can also be conﬁgured to provide a single 3-phase

output for even higher output currents.

A wide 4.5V to 24V (28V maximum) input voltage sup-

ply range encompasses most battery chemistries and

intermediate bus voltages. Phase 3 can regulate output

voltages up to 13.5V. A constant frequency current mode

architecture allows for a phase-lockable frequency up to

750kHz.

Independent TK/SS pins for each output ramps the output

voltages and can be conﬁgured for coincident or ratiometric

tracking. Current foldback limits MOSFET heat dissipation

during short-circuit conditions. The MODE/PLLIN pin

selects among Burst Mode

®

operation, pulse-skipping or

continuous inductor current modes.

Triple, 120° Phased Controllers Reduce Required

Input Capacitance and Power Supply Induced Noise

Conﬁgurable as a 180° Dual Phase Controller Plus a

Single Phase Controller

The Third Phase Can Regulate Up to a 13.5V Output

High Efﬁciency: Up to 92%

R

SENSE

or DCR Current Sensing

±0.75% 0.8V Output Voltage Accuracy

Phase-Lockable Fixed Frequency 250kHz to 750kHz

Supports Pre-Biased Outputs

Dual N-Channel MOSFET Synchronous Drive

Wide V

IN

Range: 4.5V to 24V Operation (28V Abs Max)

Adjustable Soft-Start Current Ramping or Tracking

Foldback Output Current Limiting

Output Overvoltage Protection

Dual Power Good Output Voltage Monitors

40-Lead 6mm

×

6mm QFN Package

L,

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

All other trademarks are the property of their respective owners. Protected by U.S. Patents,

including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6304066, 6580258.

TYPICAL APPLICATION

High Efﬁciency Triple 5V/3.3V/1.2V Step-Down Converter

V

IN

7V TO 24V

4.7μF

V

IN

TG1

PGOOD12

PGOOD3

SW1

BG1

f

IN

500kHz

INTV

CC

TG2

BOOST1,2,3

SW2

BG2

2.2k

1k

0.1μF

SW1,2,3

2.2μH

1μH

22μF

50V

2.2μH

LTC3853

2.2k

0.1μF

MODE/PLLIN

PGND

I

LIM

FREQ/PLLFLTR

SENSE1

+

SENSE1

–

SENSE2

+

SENSE2

–

V

FB2

10nF

RUN1,2,3

TG3

SW3

BG3

SENSE3

+

SENSE3

–

TK/SS1,2,3

0.1μF

10k

20k

0.1μF

V

OUT2

3.3V

5A

0.1μF

V

OUT1

5V

5A

63.4k

105k

1500pF

220pF

100μF

10V

20k

15k

V

FB1

I

TH1,2,3

V

FB3

SGND

+

100μF

6V

10k

V

OUT3

1.2V

5A

+

20k

+

100μF

6V

3853f

1

LTC3853

ABSOLUTE MAXIMUM RATINGS

(Note 1)

PIN CONFIGURATION

TOP VIEW

FREQ/PLLFLTR

MODE/PLLIN

Input Supply Voltage (V

IN

) ......................... 28V to –0.3V

Topside Driver Voltages

BOOST1, BOOST2, BOOST3 .................. 34V to –0.3V

Switch Voltage (SW1, SW2, SW3) ................ 28V to –5V

INTV

CC

, RUN1, RUN2, RUN3, PGOOD12, PGOOD3,

DRV

CC12

, EXTV

CC

, (BOOST1-SW1),

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

SENSE1

+

, SENSE2

+

, SENSE1

–

,

SENSE2

–

Voltages..................................... 5.7V to –0.3V

SENSE3

+

, SENSE3

–

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

V

FB2

........................................................ 300μA Max I

FB2

MODE/PLLIN, I

LIM

,TK/SS1,

TK/SS2, TK/SS3 Voltages ..................... INTV

CC

to –0.3V

I

TH1

, I

TH2

, I

TH3

, V

FB1

, V

FB3

Voltages ...... INTV

CC

to –0.3V

INTV

CC

Peak Output Current ................................150mA

Operating Temperature Range (Note 2)

LTC3853E............................................. –40°C to 85°C

LTC3853I............................................ –40°C to 125°C

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

Storage Temperature Range................... –65°C to 125°C

BOOST1

TK/SS1

RUN1

RUN2

RUN3

40 39 38 37 36 35 34 33 32 31

TK/SS2 1

TK/SS3 2

SNSP1 3

SNSN1 4

SNSP2 5

SNSN2 6

SNSP3 7

SNSN3 8

V

FB1

9

I

TH1

10

11 12 13 14 15 16 17 18 19 20

SGND

I

TH2

I

TH3

TG3

PGOOD3

PGOOD12

BOOST3

SW3

V

FB2

V

FB3

41

30 BG1

29 DRV

CC12

28 BG2

27 SW2

26 TG2

25 BOOST2

24 V

IN

23 EXTV

CC

22 INTV

CC

21 BG3

UJ PACKAGE

40-LEAD (6mm

×

6mm) PLASTIC QFN

T

JMAX

= 125°C,

θ

JA

= 33°C/W

EXPOSED PAD (PIN 41) IS PGND, MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

LTC3853EUJ#PBF

LTC3853IUJ#PBF

LEAD BASED FINISH

LTC3853EUJ

LTC3853IUJ

TAPE AND REEL

LTC3853EUJ#TRPBF

LTC3853IUJ#TRPBF

TAPE AND REEL

LTC3853EUJ#TR

LTC3853IUJ#TR

PART MARKING*

LTC3853

PART MARKING*

LTC3853

PACKAGE DESCRIPTION

40-Lead (6mm

×

6mm) Plastic QFN

40-Lead (6mm

×

6mm) Plastic QFN

PACKAGE DESCRIPTION

40-Lead (6mm

×

6mm) Plastic QFN

40-Lead (6mm

×

6mm) Plastic QFN

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 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/

SW1

I

LIM

TG1

3853f

2

LTC3853

ELECTRICAL CHARACTERISTICS

SYMBOL

V

FB1,2,3

I

FB1,2,3

V

REFLNREG

V

LOADREG

PARAMETER

Regulated Feedback Voltage

Feedback Current

Reference Voltage Line Regulation

Output Voltage Load Regulation

Main Control Loops

I

TH1,2,3

Voltage = 1.2V (Note 4)

I

TH1,2,3

Voltage = 1.2V (0°C to 85°C) (Note 4)

(Note 4)

V

IN

= 6V to 24V (Note 4)

(Note 4)

Measured in Servo Loop;

ΔI

TH

Voltage = 1.2V to 0.7V

Measured in Servo Loop;

ΔI

TH

Voltage = 1.2V to 1.6V

g

m1,2,3

I

Q

Transconductance Ampliﬁer g

m

Input DC Supply Current

Normal Mode

Shutdown

Undervoltage Lockout on INTV

CC

UVLO Hysteresis

Feedback Overvoltage Lockout

Sense Pin Current

Soft-Start Charge Current

RUN Pin ON Threshold

RUN Pin Hysteresis

Maximum Current Sense Threshold

I

TH1,2,3

= 1.85V, V

SENSE1,2,3

= 3.3V, I

LIM

= 0V

I

TH1,2,3

= 1.85V, V

SENSE1,2,3

= 3.3V, I

LIM

= Float

I

TH1,2,3

= 1.85V, V

SENSE1,2,3

= 3.3V, I

LIM

= INTV

CC

In Dropout

TG High

TG Low

BG High

BG Low

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

(Note 6)

C

LOAD

= 3300pF Each Driver

(Note 6)

C

LOAD

= 3300pF Each Driver

(Note 7)

l

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C, V

IN

= 15V, V

RUN1,2,3

= 5V, unless otherwise noted.

CONDITIONS

MIN

0.792

0.794

TYP

0.800

–10

0.002

MAX

0.808

0.806

–50

0.02

UNITS

V

nA

%/V

l

0.01

–0.01

2.2

4.1

42

3.35

0.5

0.1

–0.1

%

mmho

mA

μA

V

I

TH1,2,3

= 1.2V, Sink/Source 5μA (Note 4)

(Note 5)

V

IN

= 15V

V

RUN1,2,3

= 0V

V

INTVCC

Ramping Down

Measured at V

FB1,2,3

V

SENSE

= 3.3V

V

TK/SS1,2,3

= 0V

V

RUN1

, V

RUN2

, V

RUN3

Rising

l

70

UVLO

HYS

V

OVL

I

SENSE

I

TK/SS1,2,3

V

RUN1,2,3

V

RUN1,2,3HYS

V

SENSE(MAX)

0.84

0.9

1.1

22

42

65

97

0.86

±1

1.3

1.2

80

30

50

75

98

2.6

1.5

2.4

1.1

25

30

90

0.88

±2

1.7

1.35

38

58

85

V

μA

V

mV

%

Ω

ns

DF

MAX

TG R

UP

TG R

DOWN

BG R

UP

BG R

DOWN

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

2D

t

ON(MIN)

Maximum Duty Factor

TG Driver Pull-Up On-Resistance

TG Driver Pull-Down On-Resistance

BG Driver Pull-Up On-Resistance

BG Driver 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

Minimum On-Time

3853f

3

LTC3853

ELECTRICAL CHARACTERISTICS

SYMBOL

V

INTVCC

V

LDO

INT

V

EXTVCC

V

LDO

EXT

V

LDOHYS

f

NOM

f

LOW

f

HIGH

Ph

TRIPLE

PARAMETER

Internal V

CC

Voltage

INTV

CC

Load Regulation

EXTV

CC

Switchover Voltage

EXTV

CC

Voltage Drop

EXTV

CC

Hysteresis

Nominal Frequency

Lowest Frequency

Highest Frequency

Channel 2-Channel 1 Phase

Channel 3-Channel 2 Phase

Channel 1-Channel 3 Phase

Channel 2-Channel 1 Phase

Channel 3-Channel 2 Phase

Channel 1-Channel 3 Phase

MODE/PLLIN Input Resistance

Phase Detector Output Current

Sinking Capability

Sourcing Capability

PGOOD Voltage Low

PGOOD Leakage Current

PGOOD Trip Level

f

MODE

< f

OSC

f

MODE

> f

OSC

I

PGOOD

= 2mA

V

PGOOD

= 5V

V

FB

with Respect to Set Regulated Voltage

V

FB

Ramping Negative

V

FB

Ramping Positive

–5

5

– 7.5

7.5

V

FB2

Tied to V

IN

Through 200kΩ

V

FREQ

= 1.2V

V

FREQ

= 0V

V

FREQ

≥ 2.4V

450

210

670

INTV

CC

Linear Regulator

7V < V

IN

< 24V

I

CC

= 0mA to 50mA

EXTV

CC

Ramping Positive

I

CC

= 20mA, V

EXTVCC

= 5V

l

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C, V

IN

= 15V, V

RUN1,2,3

= 5V, unless otherwise noted.

CONDITIONS

MIN

4.8

4.5

TYP

5

0.5

4.7

30

200

500

250

750

120

180

60

120

250

–13

13

0.1

0.3

±2

–10

10

550

290

830

75

MAX

5.2

2

UNITS

V

%

V

mV

kHz

Deg

kΩ

μA

V

μA

%

Oscillator and Phase-Locked Loop

Ph

DUAL(2+1)

R

MODE/PLLIN

I

FREQ

PGOOD Outputs

V

PGL

I

PGOOD

V

PG

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 LTC3853E is guaranteed to meet performance speciﬁcations

from 0°C to 85°C. Speciﬁcations over the –40°C to 85°C operating

temperature range are assured by design, characterization and correlation

with statistical process controls. The LTC3853I is guaranteed over the full

–40°C to 125°C operating temperature range.

Note 3:

T

J

is calculated from the ambient temperature T

A

and power

dissipation P

D

according to the following formulas:

LTC3853EUJ: T

J

= T

A

+ (P

D

• 33°C/W)

Note 4:

The LTC3853 is tested in a feedback loop that servos V

ITH1,2,3

to a

speciﬁed voltage and measures the resultant V

FB1,2,3

.

Note 5:

Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. See Applications Information.

Note 6:

Rise and fall times are measured using 10% and 90% levels.

Delay times are measured using 50% levels.

Note 7:

The minimum on-time condition is speciﬁed for an inductor

peak-to-peak ripple current ≥40% of I

MAX

(see Minimum On-Time

Considerations in the Applications Information section).

3853f

4

LTC3853

TYPICAL PERFORMANCE CHARACTERISTICS

Efﬁciency vs Output Current

and Mode

100

90

80

EFFICIENCY (%)

BURST

EFFICIENCY (%)

70

60

50

40

30

20

10

0

1.00E-02

V

IN

= 12V

V

OUT

= 1.8V

FIGURE 15 MODIFIED

WITH DCR SENSING

1.00E-01

1.00E+00

LOAD CURRENT (mA)

1.00E+01

3853 G01

Efﬁciency vs Output Current

and Mode

100

90

80

70

60

50

40

30

20

10

0

1.00E-02

V

IN

= 12V

V

OUT

= 3.3V

FIGURE 15 MODIFIED

WITH DCR SENSING

1.00E-01

1.00E+00

LOAD CURRENT (mA)

1.00E+01

3853 G02

Efﬁciency and Power Loss

vs Input Voltage

100

95

2.0

1.8

1.6

EFFICIENCY

BURST

EFFICIENCY (%)

90

85

80

75

70

65

60

0

5

POWER LOSS (mW)

1.4

1.2

1.0

DCM

CCM

DCM

POWER LOSS

V

OUT

= 3.3V

I

OUT

= 2A

FIGURE 15 MODIFIED

WITH DCR SENSING

20

15

INPUT VOLTAGE (V)

10

25

30

3853 G03

0.8

0.6

0.4

0.2

0

Load Step

(Burst Mode Operation)

I

LOAD

2A/DIV

I

LOAD

2A/DIV

Load Step

(Forced Continuous Mode)

I

L

2A/DIV

V

OUT

100mV/DIV

AC COUPLED

40μs/DIV

V

IN

= 12V

V

OUT

= 3.3V

I

LOAD

= 0A TO 3A

FIGURE 15 CIRCUIT

3853 G04

I

L

2A/DIV

V

OUT

100mV/DIV

AC COUPLED

40μs/DIV

V

IN

= 12V

V

OUT

= 3.3V

I

LOAD

= 0A TO 3A

FIGURE 15 CIRCUIT

3853 G05

Load Step

(Pulse Skip Mode)

I

LOAD

2A/DIV

FORCED

CONTINUOUS

MODE

2A/DIV

Burst Mode

OPERATION

2A/DIV

PULSE SKIPPING

MODE

2A/DIV

40μs/DIV

V

IN

= 12V

V

OUT

= 3.3V

I

LOAD

= 0A TO 3A

FIGURE 15 CIRCUIT

3853 G06

Inductor Current at Light Load

I

L

2A/DIV

V

OUT

100mV/DIV

AC COUPLED

1μs/DIV

V

IN

= 12

V

OUT

= 1.8V

I

LOAD

= 100mA

FIGURE 15 CIRCUIT

3853 G07

3853f

5

参数名称	属性值
是否无铅	含铅
是否Rohs认证	不符合
厂商名称	Linear ( ADI )
零件包装代码	QFN
包装说明	HVQCCN, LCC40,.24SQ,20
针数	40
Reach Compliance Code	_compli
ECCN代码	EAR99
模拟集成电路 - 其他类型	DUAL SWITCHING CONTROLLER
控制模式	CURRENT-MODE
控制技术	PULSE WIDTH MODULATION
最大输入电压	24 V
最小输入电压	4.5 V
标称输入电压	15 V
JESD-30 代码	S-PQCC-N40
JESD-609代码	e0
长度	6 mm
湿度敏感等级	1
功能数量	1
端子数量	40
最高工作温度	125 °C
最低工作温度	-40 °C
最大输出电流	0.15 A
标称输出电压	5 V
封装主体材料	PLASTIC/EPOXY
封装代码	HVQCCN
封装等效代码	LCC40,.24SQ,20
封装形状	SQUARE
封装形式	CHIP CARRIER, HEAT SINK/SLUG, VERY THIN PROFILE
峰值回流温度（摄氏度）	235
认证状态	Not Qualified
座面最大高度	0.8 mm
表面贴装	YES
切换器配置	PHASE-SHIFT
最大切换频率	830 kHz
技术	CMOS
温度等级	AUTOMOTIVE
端子面层	Tin/Lead (Sn/Pb)
端子形式	NO LEAD
端子节距	0.5 mm
端子位置	QUAD
处于峰值回流温度下的最长时间	20
宽度	6 mm

LTC3853IUJ

LTC3853IUJ概述

LTC3853IUJ规格参数

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