FEATURES

n

LTC3827

Low I

Q

, Dual, 2-Phase

Synchronous Step-Down Controller

DESCRIPTION

The LTC

®

3827 is a high performance dual step-down

switching regulator controller that drives all N-channel

synchronous power MOSFET stages. A constant frequency

current mode architecture allows a phase-lockable fre-

quency of up to 650kHz. Power loss and noise due to the

ESR of the input capacitor ESR are minimized by operating

the two controller output stages out of phase.

The 80μA no-load quiescent current extends operating

life in battery-powered systems. OPTI-LOOP compensa-

tion allows the transient response to be optimized over

a wide range of output capacitance and ESR values. The

LTC3827 features a precision 0.8V reference and a power

good output indicator. A wide 4V to 36V input supply range

encompasses all battery chemistries.

Independent TRACK/SS pins for each controller ramp the

output voltage during start-up. Current foldback limits

MOSFET heat dissipation during short-circuit conditions.

The PLLIN/MODE pin selects among Burst Mode opera-

tion, pulse skipping mode, or continuous inductor cur-

rent mode at light loads. For a leaded package version

(28-lead SSOP), see the LTC3827-1 datasheet.

L,

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

Burst Mode and OPTI-LOOP are registered trademarks of Linear Technology Corporation.

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

including 5481178, 5929620, 6177787, 6144194, 5408150, 6580258, 6304066, 570919.

n

Wide Output Voltage Range: 0.8V ≤ V

OUT

≤ 10V

Low Operating I

Q

: 80μA (One Channel On)

Out-of-Phase Controllers Reduce Required Input

Capacitance and Power Supply Induced Noise

OPTI-LOOP

®

Compensation Minimizes C

OUT

±1% Output Voltage Accuracy

Wide V

IN

Range: 4V to 36V Operation

Phase-Lockable Fixed Frequency 140kHz to 650kHz

Selectable Continuous, Pulse Skipping or

Low Ripple

Burst Mode

®

Operation at Light Loads

Dual N-Channel MOSFET Synchronous Drive

Very Low Dropout Operation: 99% Duty Cycle

Adjustable Output Voltage Soft-Start or Tracking

Output Current Foldback Limiting

Power Good Output Voltage Monitor

Output Overvoltage Protection

Low Shutdown I

Q

: 8μA

Internal LDO Powers Gate Drive from V

IN

or V

OUT

Small 5mm

×

5mm QFN Package

APPLICATIONS

n

Automotive Systems

Battery-Operated Digital Devices

Distributed DC Power Systems

TYPICAL APPLICATION

High Efﬁciency Dual 8.5V/3.3V Step-Down Converter

+

4.7μF

V

IN

TG1

3.3μH

0.1μF

BOOST1

SW1

BG1

LTC3827

SENSE1

+

0.015Ω

V

OUT1

3.3V

5A

SENSE1

–

V

FB1

62.5k

150μF

220pF

20k

15k

I

TH1

SENSE2

–

V

FB2

I

TH2

220pF

15k

20k

192.5k

INTV

CC

TG2

BOOST2

SW2

BG2

PGND

SENSE2

+

0.015Ω

V

OUT2

8.5V

3.5A

150μF

0.1μF

EFFICIENCY (%)

7.2μH

V

IN

4V TO 36V

1μF

22μF

50V

100

90

80

70

60

50

40

30

20

10

0

0.001 0.01

0.1

1

10 100 1000 10000

LOAD CURRENT (mA)

3827 TA01b

Efﬁciency and Power Loss

vs Load Current

100000

EFFICIENCY

V

IN

= 12V; V

OUT

= 3.3V

10000

POWER LOSS (mW)

1000

100

POWER LOSS

10

1

FIGURE 13 CIRCUIT

TRACK/SS1 SGND TRACK/SS2

0.1μF

3827 TA01

3827ff

1

LTC3827

ABSOLUTE MAXIMUM RATINGS

(Note 1)

PIN CONFIGURATION

TOP VIEW

TRACK/SS1

SENSE1

+

PGOOD2

PGOOD1

SW1

24 BOOST1

23 BG1

22 V

IN

33

21 PGND

20 EXTV

CC

19 INTV

CC

18 BG2

17 BOOST2

9 10 11 12 13 14 15 16

FOLDDIS

TG2

TRACK/SS2

SENSE2

–

SENSE2

+

SW2

V

FB2

I

TH2

V

FB1

I

TH1

TG1

Input Supply Voltage (V

IN

) .........................36V to – 0.3V

Topside Driver Voltages

BOOST1, BOOST2.................................. 42V to –0.3V

Switch Voltage (SW1, SW2) ......................... 36V to –5V

BOOST1-SW1, BOOST2-SW2 .................. 8.5V to –0.3V

RUN1, RUN2 ............................................... 7V to –0.3V

SENSE1

+

, SENSE2

+

, SENSE1

–

,

SENSE2

–

Voltages .................................... 11V to –0.3V

PLLIN/MODE, PLLLPF Voltages ........... INTV

CC

to –0.3V

,

PHASMD, FOLDDIS, TRACK/SS1, TRACK/SS2

Voltages ............................................... INTV

CC

to –0.3V

EXTV

CC

...................................................... 10V to –0.3V

I

TH1,

I

TH2

, V

FB1

, V

FB2

Voltages .................. 2.7V to –0.3V

PGOOD1, PGOOD2 Voltages ..................... 8.5V to –0.3V

Peak Output Current <10μs (TG1, TG2, BG1, BG2) .....3A

INTV

CC

Peak Output Current ................................. 50mA

Operating Temperature Range (Note 2).... –40°C to 85°C

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

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

32 31 30 29 28 27 26 25

SENSE1

–

1

PLLLPF 2

PHASMD 3

CLKOUT 4

PLLIN/MODE 5

SGND 6

RUN1 7

RUN2 8

UH PACKAGE

32-LEAD (5mm

×

5mm) PLASTIC QFN

T

JMAX

= 125°C,

θ

JA

= 34°C/W

EXPOSED PAD (PIN 33) IS SGND

MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

LTC3827EUH#PBF

LTC3827IUH#PBF

LEAD BASED FINISH

LTC3827EUH

LTC3827IUH

TAPE AND REEL

LTC3827EUH#TRPBF

LTC3827IUH#TRPBF

TAPE AND REEL

LTC3827EUH#TR

LTC3827IUH#TR

PART MARKING*

3827

PART MARKING*

3827

PACKAGE DESCRIPTION

32-Lead (5mm

×

5mm) Plastic QFN

32-Lead (5mm

×

5mm) Plastic QFN

PACKAGE DESCRIPTION

32-Lead (5mm

×

5mm) Plastic QFN

32-Lead (5mm

×

5mm) Plastic QFN

TEMPERATURE RANGE

–40°C to 85°C

TEMPERATURE RANGE

–40°C to 85°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/

3827ff

2

LTC3827

ELECTRICAL CHARACTERISTICS

SYMBOL

V

FB1, 2

I

VFB1, 2

V

REFLNREG

V

LOADREG

PARAMETER

Regulated Feedback Voltage

Feedback Current

Reference Voltage Line Regulation

Output Voltage Load Regulation

Main Control Loops

(Note 4) I

TH1, 2

Voltage = 1.2V

(Note 4)

V

IN

= 4V to 30V (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 2V

I

TH1, 2

= 1.2V; Sink/Source 5μA (Note 4)

(Note 5)

RUN1 = 5V, RUN2 = 0V, V

FB1

= 0.83V (No Load)

RUN1 = 0V, RUN2 = 5V, V

FB2

= 0.83V (No Load)

V

RUN1, 2

= 0V

RUN1,2 = 5V, V

FB1

= V

FB2

= 0.83V

V

IN

Ramping Down

Measured at V

FB1, 2

, Relative to Regulated V

FB1, 2

(Each Channel) V

SENSE1

–

, 2

– = V

SENSE1

+

, 2

+ = 0V

In Dropout

V

TRACK1, 2

= 0V

V

RUN1,

V

RUN2

Rising

V

FB1, 2

= 0.7V,V

SENSE1–, 2–

= 3.3V

V

FB1, 2

= 0.7V,V

SENSE1–, 2–

= 3.3V

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

(Note 6)

C

LOAD

= 3300pF

C

LOAD

= 3300pF

●

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= 12V, V

RUN/SS1, 2

= 5V unless otherwise noted.

CONDITIONS

MIN

0.792

TYP

0.800

–5

0.002

0.1

– 0.1

1.55

80

8

115

3.5

8

98

0.75

0.5

90

80

10

–660

99.4

1.0

0.7

100

50

40

70

180

5.0

7.2

4.5

5.25

0.2

7.5

0.2

4.7

0.2

V

PLLLPF

= Floating; PLLIN/MODE = DC Voltage

V

PLLLPF

= 0V; PLLIN/MODE = DC Voltage

V

PLLLPF

= INTV

CC

; PLLIN/MODE = DC Voltage

PLLIN/MODE = External Clock; V

PLLLPF

= 0V

360

220

475

400

250

530

115

440

280

580

140

5.5

1.0

7.8

1.0

1.35

0.9

110

115

90

80

125

20

160

4

12

MAX

0.808

–50

0.02

0.5

–0.5

UNITS

V

nA

%/V

%

mmho

μA

V

%

μA

%

μA

V

mV

ns

V

%

V

%

V

kHz

g

m1, 2

I

Q

Transconductance Ampliﬁer g

m

Input DC Supply Current

Sleep Mode (Channel 1 On)

Sleep Mode (Channel 2 On)

Shutdown

Sleep Mode (Both Channels)

Undervoltage Lockout

Feedback Overvoltage Lockout

Sense Pins Total Source Current

Maximum Duty Factor

RUN Pin ON Threshold

Maximum Current Sense Threshold

TG Transition Time:

Rise Time

Fall Time

BG Transition Time:

Rise Time

Fall Time

UVLO

V

OVL

I

SENSE

DF

MAX

V

RUN1, 2

ON

V

SENSE(MAX)

I

TRACK/SS1, 2

Soft-Start Charge Current

TG1, 2 t

r

TG1, 2 t

f

BG1, 2 t

r

BG1, 2 t

f

TG/BG t

1D

BG/TG t

2D

t

ON(MIN)

V

INTVCCVIN

V

LDOVIN

V

INTVCCEXT

V

LDOEXT

V

EXTVCC

V

LDOHYS

f

NOM

f

LOW

f

HIGH

f

SYNCMIN

Top Gate Off to Bottom Gate On Delay C

LOAD

= 3300pF Each Driver

Synchronous Switch-On Delay Time

Bottom Gate Off to Top Gate On Delay C

LOAD

= 3300pF Each Driver

Top Switch-On Delay Time

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

Nominal Frequency

Lowest Frequency

Highest Frequency

Minimum Synchronizable Frequency

(Note 7)

8.5V < V

IN

< 30V, V

EXTVCC

= 0V

I

CC

= 0mA to 20mA, V

EXTVCC

= 0V

V

EXTVCC

= 8.5V

I

CC

= 0mA to 20mA, V

EXTVCC

= 8.5V

EXTV

CC

Ramping Positive

INTV

CC

Linear Regulator

Oscillator and Phase-Locked Loop

3827ff

3

LTC3827

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= 12V, V

RUN/SS1, 2

= 5V unless otherwise noted.

SYMBOL

f

SYNCMAX

I

PLLLPF

PARAMETER

Maximum Synchronizable Frequency

Phase Detector Output Current

Sinking Capability

Sourcing Capability

PGOOD Voltage Low

PGOOD Leakage Current

PGOOD Trip Level

CONDITIONS

PLLIN/MODE = External Clock; V

PLLLPF

= 2V

f

PLLIN/MODE

< f

OSC

f

PLLIN/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

–12

8

–10

10

MIN

650

TYP

800

–5

5

0.1

0.3

±1

–8

12

MAX

UNITS

kHz

μA

V

μA

%

ELECTRICAL CHARACTERISTICS

PGOOD Output

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 LTC3827E 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 LTC3827I is guaranteed to meet

performance speciﬁcations over the full –40°C to 85°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:

T

J

= T

A

+ (P

D

• 34 °C/W)

Note 4:

The LTC3827 is tested in a feedback loop that servos V

ITH1, 2

to a

speciﬁed voltage and measures the resultant V

FB1, 2.

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).

3827ff

4

LTC3827

TYPICAL PERFORMANCE CHARACTERISTICS

Efﬁciency and Power Loss

vs Output Current

100

90

80

70

EFFICIENCY (%)

60

50

40

30 V

IN

= 12V

V

OUT

= 3.3V

20

10

0

0.001 0.01

0.1

1

10 100 1000 10000

LOAD CURRENT (mA)

3827 G01

Efﬁciency vs Load Current

10000

100

90

80

70

60

50

40

0.001 0.01

FIGURE 13 CIRCUIT

0.1

1

10 100 1000 10000

LOAD CURRENT (mA)

3827 G02

Efﬁciency vs Input Voltage

98

96

94

Burst Mode OPERATION

FORCED CONTINUOUS MODE

PULSE SKIPPING MODE

1000

POWER LOSS (mW)

EFFICIENCY (%)

V

IN

= 12V

V

IN

= 5V

V

OUT

= 3.3V

EFFICIENCY (%)

100

92

90

88

86

10

1

FIGURE 13 CIRCUIT

84

82

0

V

OUT

= 3.3V

FIGURE 13 CIRCUIT

5

10

15 20 25 30

INPUT VOLTAGE (V)

35

40

3827 G03

Load Step

(Burst Mode Operation)

Load Step

(Forced Continuous Mode)

Load Step

(Pulse Skip Mode)

V

OUT

100mV/DIV

AC

COUPLED

V

OUT

100mV/DIV

AC

COUPLED

V

OUT

100mV/DIV

AC

COUPLED

I

L

2A/DIV

I

L

2A/DIV

I

L

2A/DIV

20μs/DIV

V

OUT

= 3.3V

FIGURE 13 CIRCUIT

3827 G04

20μs/DIV

V

OUT

= 3.3V

FIGURE 13 CIRCUIT

3827 G05

20μs/DIV

V

OUT

= 3.3V

FIGURE 13 CIRCUIT

3827 G06

Inductor Current at Light Load

Soft Start-Up

V

OUT2

2V/DIV

Tracking Start-Up

V

OUT2

2V/DIV

FORCED

CONTINUOUS

MODE

2A/DIV

BURST MODE

OPERATION

PULSE

SKIPPING

MODE

4μs/DIV

V

OUT

= 3.3V

I

LOAD

= 300μA

FIGURE 13 CIRCUIT

3827 G07

V

OUT1

2V/DIV

V

OUT1

2V/DIV

20ms/DIV

FIGURE 13 CIRCUIT

3827 G08

20ms/DIV

FIGURE 13 CIRCUIT

3827 G09

3827ff

5

参数名称	属性值
Brand Name	Linear Technology
是否Rohs认证	不符合
厂商名称	Linear ( ADI )
零件包装代码	SSOP
包装说明	SSOP, SSOP28,.3
针数	28
制造商包装代码	G
Reach Compliance Code	_compli
ECCN代码	EAR99
其他特性	ALSO OPERATES IN ADJUSTABLE MODE FROM 0.8 TO 10V
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	36 V
最小输入电压	4 V
标称输入电压	12 V
JESD-30 代码	R-PDSO-G28
JESD-609代码	e0
长度	10.2 mm
湿度敏感等级	1
功能数量	1
端子数量	28
最高工作温度	85 °C
最低工作温度
最大输出电流	3 A
标称输出电压	5.25 V
封装主体材料	PLASTIC/EPOXY
封装代码	SSOP
封装等效代码	SSOP28,.3
封装形状	RECTANGULAR
封装形式	SMALL OUTLINE, SHRINK PITCH
峰值回流温度（摄氏度）	235
认证状态	Not Qualified
座面最大高度	2 mm
表面贴装	YES
切换器配置	PHASE-SHIFT
最大切换频率	650 kHz
技术	CMOS
温度等级	OTHER
端子面层	Tin/Lead (Sn/Pb)
端子形式	GULL WING
端子节距	0.65 mm
端子位置	DUAL
处于峰值回流温度下的最长时间	20
宽度	5.3 mm

	LTC3827EG-1#TR	LTC3827EUH#TR
描述	LTC3827-1 - Low IQ, Dual, 2-Phase Synchronous Step-Down Controller; Package: SSOP; Pins: 28; Temperature Range: -40°C to 85°C	LTC3827 - Low IQ, Dual, 2-Phase Synchronous Step-Down Controller; Package: QFN; Pins: 32; Temperature Range: -40°C to 85°C
Brand Name	Linear Technology	Linear Technology
是否Rohs认证	不符合	不符合
厂商名称	Linear ( ADI )	Linear ( ADI )
零件包装代码	SSOP	QFN
包装说明	SSOP, SSOP28,.3	HVQCCN, LCC32,.2SQ,20
针数	28	32
制造商包装代码	G	UH
Reach Compliance Code	_compli	_compli
ECCN代码	EAR99	EAR99
模拟集成电路 - 其他类型	DUAL SWITCHING CONTROLLER	DUAL SWITCHING CONTROLLER
控制模式	CURRENT-MODE	CURRENT-MODE
控制技术	PULSE WIDTH MODULATION	PULSE WIDTH MODULATION
最大输入电压	36 V	36 V
最小输入电压	4 V	4 V
标称输入电压	12 V	12 V
JESD-30 代码	R-PDSO-G28	S-PQCC-N32
JESD-609代码	e0	e0
长度	10.2 mm	5 mm
湿度敏感等级	1	1
功能数量	1	1
端子数量	28	32
最高工作温度	85 °C	85 °C
最大输出电流	3 A	3 A
封装主体材料	PLASTIC/EPOXY	PLASTIC/EPOXY
封装代码	SSOP	HVQCCN
封装等效代码	SSOP28,.3	LCC32,.2SQ,20
封装形状	RECTANGULAR	SQUARE
封装形式	SMALL OUTLINE, SHRINK PITCH	CHIP CARRIER, HEAT SINK/SLUG, VERY THIN PROFILE
峰值回流温度（摄氏度）	235	235
认证状态	Not Qualified	Not Qualified
座面最大高度	2 mm	0.8 mm
表面贴装	YES	YES
切换器配置	PHASE-SHIFT	PHASE-SHIFT
最大切换频率	650 kHz	580 kHz
技术	CMOS	CMOS
温度等级	OTHER	OTHER
端子面层	Tin/Lead (Sn/Pb)	Tin/Lead (Sn/Pb)
端子形式	GULL WING	NO LEAD
端子节距	0.65 mm	0.5 mm
端子位置	DUAL	QUAD
处于峰值回流温度下的最长时间	20	20
宽度	5.3 mm	5 mm

LTC3827EG-1#TR

LTC3827EG-1#TR概述

LTC3827EG-1#TR规格参数

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