LTC3545EUD#TRPBF datasheet, PDF

LTC3545/LTC3545-1

Triple 800mA Synchronous

Step-Down Regulator–2.25MHz

FEATURES

■

DESCRIPTION

The LTC

®

3545/LTC3545-1 are triple, high efficiency,

monolithic synchronous buck regulators using a constant

frequency, current mode architecture. The regulators op-

erate independently with separate run pins. The 2.25V to

5.5V input voltage range makes the LTC3545/LTC3545-1

well suited for single Li-Ion battery-powered applications.

Low ripple pulse skip mode or high efﬁciency Burst Mode

operation is externally selectable. PWM pulse skip mode

operation provides very low output ripple voltage while

Burst Mode operation increases efﬁciency at low output

loads.

Switching frequency is internally set to 2.25MHz, or the

switching frequency can be synchronized to an external

1MHz to 3MHz clock. Power good indicators easily allow

power on sequencing between the three regulators.

The internal synchronous switches increase efﬁciency and

eliminate external Schottky diodes. Low output voltages are

supported with the 0.6V feedback reference voltage.

The LTC3545-1 replaces the SYNC/MODE function with a

third PGOOD pin and forces Burst Mode operation.

■

Three 800mA Outputs

High Efﬁciency: Up to 95%

2.25V to 5.5V Input Voltage Range

Low Ripple (<20mV

P-P

) Burst Mode

®

Operation

I

Q

: 58μA

2.25MHz Constant Frequency Operation or

Synchronizable to External 1MHz to 3MHz Clock

Power Good Indicators Ease Supply Sequencing

0.6V Reference Allows Low Output Voltages

Current Mode Operation/Excellent Transient Response

Low Proﬁle 16-Lead 3mm

×

3mm QFN Package

APPLICATIONS

■

Smart Phones

Wireless and DSL Modems

Digital Still Cameras

Portable Instruments

Point of Load Regulation

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 6580258, 5481178, 6127815, 6498466, 6611131.

TYPICAL APPLICATION

High Efﬁciency Triple Step-Down Converter with Power Sequencing

V

IN

2.25V TO 5.5V

C4 10μF

GNDA

R8

500k

R7

500k

RUN1

PGOOD1

RUN2

PGOOD2

RUN3

L1

1.5μH

C6

20pF

LTC3545

L3

1.5μH

SW3

C8

20pF

V

FB2

R4

226k

R3

226k

C2

10μF

V

IN

PV

IN

C5

10μF

PGND

L2

1.5μH

C7

20pF

Efﬁciency and Loss vs Load Current

100

90

80

EFFICIENCY (%)

V

OUT2

1.2V

70

60

50

40

30

20

10

V

OUT3

1.5V

C3

10μF

R5

301k

3545 TA01

1

0.1

LOSS (W)

SW2

0.01

0.001

V

IN

= 2.5V

V

IN

= 3.6V

V

IN

= 4.2V

0.01

0.1

0.001

LOAD CURRENT (A)

1

3545 TA01b

SYNC/MODE

SW1

V

OUT1

1.8V

C1

10μF

0

0.0001

V

FB1

R1

511k

R2

255k

GNDA

PGND

V

FB3

R6

200k

T

A

= 25°C

V

OUT

= 2V

Burst Mode OPERATION

f

OSC

= 2.25MHz

SINGLE CHANNEL

35451fb

1

LTC3545/LTC3545-1

ABSOLUTE MAXIMUM RATINGS

(Note 1)

Input Supply Voltage .................................... –0.3V to 6V

RUNx, PGOODx............................. –0.3V to (V

IN

+ 0.3V)

V

FBx

, SYNC/MODE ........................ –0.3V to (V

IN

+ 0.3V)

SWx .............................................. –0.3V to (V

IN

+ 0.3V)

P-Switch Source Current (DC) (Note 8) ...................1.1A

N-Channel Sink Current (DC) (Note 8) .....................1.1A

Peak SW Sink and Source Current (Note 8) .............1.3A

Operating Junction Temperature Range

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

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

PIN CONFIGURATION

LTC3545

TOP VIEW

GNDA

RUN1

V

FB1

V

IN

LTC3545-1

TOP VIEW

GNDA

RUN1

V

FB1

12 V

FB2

17

11 V

FB3

10 RUN3

9

5

SW2

6

PGND

7

PV

IN

8

SW3

PGOOD3

V

IN

16 15 14 13

SW1 1

PGOOD1 2

RUN2 3

PGOOD2 4

5

SW2

6

PGND

7

PV

IN

8

SW3

17

12 V

FB2

11 V

FB3

10 RUN3

9

SYNC/MODE

SW1 1

PGOOD1 2

RUN2 3

PGOOD2 4

16 15 14 13

UD PACKAGE

16-LEAD (3mm 3mm) PLASTIC QFN

T

JMAX

= 125°C,

θ

JA

= 55°C/W

EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB

UD PACKAGE

16-LEAD (3mm 3mm) PLASTIC QFN

T

JMAX

= 125°C,

θ

JA

= 55°C/W

EXPOSED PAD (PIN 17) IS GND, MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

LTC3545EUD#PBF

LTC3545IUD#PBF

LTC3545EUD-1#PBF

LTC3545IUD-1#PBF

TAPE AND REEL

LTC3545EUD#TRPBF

LTC3545IUD#TRPBF

LTC3545EUD-1#TRPBF

LTC3545IUD-1#TRPBF

PART MARKING*

LCSR

LDDP

PACKAGE DESCRIPTION

16-Lead (3mm

×

3mm) Plastic QFN

16-Lead (3mm

×

3mm) Plastic QFN

16-Lead (3mm

×

3mm) Plastic QFN

16-Lead (3mm

×

3mm) Plastic QFN

TEMPERATURE RANGE

–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.

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/

ELECTRICAL CHARACTERISTICS

SYMBOL

V

IN

V

FBx

PARAMETER

Input Voltage Range

Regulated Feedback Voltage (Note 5)

General Characteristics

The

●

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= PV

IN

= 3.6V unless otherwise noted. (Note 2)

CONDITIONS

●

MIN

2.25

0.592

0.588

TYP

MAX

5.5

UNITS

V

%/V

35451fb

T

A

= 25°C

0°C ≤ T

A

≤ 85°C

LTC3545IUD; –40°C < T

A

< 125°C

V

IN

= 2.25V to 5.5V

●

0.6

0.08

0.608

0.612

0.15

ΔV

FBx

Reference Voltage Line Regulation (Note 5)

2

LTC3545/LTC3545-1

ELECTRICAL CHARACTERISTICS

SYMBOL

V

LOADREG

I

FBx

I

S

PARAMETER

Output Voltage Load Regulation (Notes 5, 6)

Feedback Pin Leakage (Note 5)

Input DC Bias Current (All Regulators Enabled)

Pulse Skip (Active Mode)

Burst Mode Operation (All Regulators Sleeping)

Shutdown (RUN

X

= 0V)

Oscillator Frequency

Synchronization Frequency

RUNx Input High Voltage

RUNx Input Low Voltage

RUN Leakage Current

SWx Leakage

SYNC Leakage

Power Good Threshold–Deviation From V

FB

Steady State (0.6V)

Power Good Pull-Down On-Resistance

V

RUNx

= 0V, V

SWx

= 0V or 5.5V, V

IN

= 5.5V

V

RUN

= 0V, V

SYNC

= 0V or 5.5V,

V

IN

= 5.5V

V

FBx

Ramping Up

V

FBx

Ramping Down

I

PGD

= 50mA

●

The

●

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= PV

IN

= 3.6V unless otherwise noted. (Note 3)

CONDITIONS

MIN

TYP

0.5

80

I

LOAD

= 0A, 2.25MHz

V

FBx

= 0.5V

V

FBx

= 0.7V

●

MAX

UNITS

%

nA

μA

MHz

V

μA

%

680

58

0.1

1.8

1

2.25

●

750

70

2.0

2.7

3

0.3

f

OSC

f

SYNC

V

RUN(HIGH)

V

RUN(LOW)

I

RUNx

I

LSWx

I

SYNC

T

PGOODx

R

PGOODx

LTC3545 Only

±0.1

–7.5

–10

14

0.93

V

FBx

= 10% to 90% Fullscale

1

I

LOAD

= 0A, 2.25MHz

V

FBx

= 0.5V

V

FBx

= 0.7V

I

SWx

= 100mA

I

SWx

= –100mA

(High V

CC

to Low)

●

±1

50

Ω

V

MODE/SYNC Thresholds

Individual Regulator Characteristics (One Regulator Enabled)

t

SS

I

PK

I

Q

Soft-Start Period

Peak Switch Current Limit

Input DC Bias Current

Pulse Skip (Active Mode)

Burst Mode Operation (Sleeping)

R

DS(ON)

of P-Channel FET (Note 7)

R

DS(ON)

of N-Channel FET (Note 7)

Undervoltage Lockout

850

1.3

310

31

0.35

1.8

1100

1.6

μs

A

μA

Ω

R

PFET

R

NFET

V

UVLO

2.25

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 LTC3545E/LTC3545E-1 are guaranteed to meet performance

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

125°C operating

junction

temperature range are assured by design,

characterization and correlation with statistical process controls. The

LTC3545I/LTC3545I-1 are guaranteed to meet performance speciﬁcations

over the full –40°C to 125°C operating

junction

temperature range.

Note 3:

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

)(68°C/W)

This IC includes overtemperature protection that is intended to protect

the device during momentary overload conditions. Junction temperature

will exceed 125°C when overtemperature is active. Continuous operation

above the speciﬁed maximum operating junction temperature may impair

device reliability.

Note 4:

This IC includes overtemperature protection that is intended

to protect the device during momentary overload conditions. Junction

temperature will exceed 125°C when overtemperature is active.

Continuous operation above the speciﬁed maximum operating junction

temperature may impair device reliability.

Note 5:

The LTC3545/LTC3545-1 are tested in a proprietary test mode that

connects V

FB

to the output of the error ampliﬁer.

Note 6:

Load regulation is inferred by measuring the regulation loop gain.

Note 7:

The QFN switch-on resistance is guaranteed by correlation to

water level measurements.

Note 8:

Guaranteed by long-term current density limitations.

35451fb

3

LTC3545/LTC3545-1

TYPICAL PERFORMANCE CHARACTERISTICS

V

REF

vs Temperature at 2.25V,

3.6V, 5.5V

0.615

SWITCHING FREQUENCY (MHz)

0.610

0.605

V

REF

(V)

0.600

0.595

0.590

0.585

–50

2.25V

3.6V

5.5V

0

50

100

TEMPERATURE (°C)

150

3545 G01

3545 G02

3545 G03

Switching Frequency vs Supply

Voltage and Temperature

3.0

1.2

1.0

0.8

V

OUT

ERROR (%)

2.5

0.6

0.4

0.2

0

–0.2

–0.4

6

Load Regulation, All Channels

T

A

= 25°C

V

IN

= 3.6V

UNTESTED CHANNELS OFF

PULSE SKIP MODE

CHANNEL 1

CHANNEL 2

CHANNEL 3

2.0

f

OSC

= –40°C

f

OSC

= 0°C

f

OSC

= 25°C

f

OSC

= 80°C

2

3

4

5

SUPPLY VOLTAGE (V)

1.5

0

200

400

600

LOAD CURRENT (mA)

800

Burst Mode Operation

100

Efﬁciency vs Supply Voltage

V

OUT

= 2V

T

A

= 25°C

CHANNEL 3, ALL OTHERS OFF

f

OSC

= 2.25MHz

I

LOAD

= 250mA

60

50

SUPPLY CURRENT (μA)

40

30

20

10

80

0

Supply Current vs Temperature

Burst Mode Operation

SW

2V/DIV

V

OUT

20mV/DIV

I

L

100mA/DIV

EFFICIENCY (%)

95

90

85

V

IN

= 3.6V

V

OUT

= 1.8V

I

LOAD

= 50mA

f

OSC

= 2.25MHz

1μs/DIV

3545 G04

V

FB3

= 0.625V

I

LOAD

= 0mA

CHANNEL 3 ONLY

–50

0

V

IN

= 5.5V

V

IN

= 4.5V

V

IN

= 3.5V

V

IN

= 2.5V

150

3545 G06

2

3

4

SUPPLY VOLTAGE (V)

5

6

3545 G05

50

100

TEMPERATURE (°C)

35451fb

4

LTC3545/LTC3545-1

TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Temperature,

Pulse Skipping

450

400

SUPPLY CURRENT (μA)

350

300

250

200

V

FB3

= 0.625V

I

LOAD

= 0mA

CHANNEL 3 ONLY

0

V

IN

= 5.5V

V

IN

= 4.5V

V

IN

= 3.5V

V

IN

= 2.5V

150

3545 G07

3545 G08

3545 G09

Efﬁciency vs Load Current,

Burst Mode Operation

100

90

80

EFFICIENCY (%)

70

60

50

40

30

20

10

V

IN

= 2.7V

V

IN

= 3.6V

V

IN

= 4.2V

T

A

= 25°C

V

OUT

= 1.8V

CHANNEL 3, OTHER CHANNELS OFF

f

OSC

= 2.25MHz

1

10

100

LOAD CURRENT (mA)

1000

EFFICIENCY (%)

100

90

80

70

60

50

40

30

20

10

Efﬁciency vs Load Current,

Pulse Skipping Operation

V

IN

= 2.7V

V

IN

= 3.6V

V

IN

= 4.2V

T

A

= 25°C

V

OUT

= 1.8V

CHANNEL 3, OTHER CHANNELS OFF

f

OSC

= 2.25MHz

1

10

100

LOAD CURRENT (mA)

1000

150

–50

50

100

TEMPERATURE (°C)

0

0.1

0

0.1

Channel 1 Load Step Response

Channel 2 Load Step Response

Channel 3 Load Step Response

V

OUT1

100mV/DIV

I

L

500mA/DIV

I

LOAD

500mA/DIV

3545 G10

V

OUT2

100mV/DIV

I

L

500mA/DIV

I

LOAD

500mA/DIV

3545 G11

V

OUT3

100mV/DIV

I

L

500mA/DIV

I

LOAD

500mA/DIV

3545 G12

T

A

= 25°C

10μs/DIV

V

IN

= 3.6V

V

OUT

= 1.2V

LOAD STEP 0mA TO 600mA

Burst Mode OPERATION

T

A

= 25°C

10μs/DIV

V

IN

= 3.6V

V

OUT

= 1.5V

LOAD STEP 0mA TO 600mA

Burst Mode OPERATION

10μs/DIV

T

A

= 25°C

V

IN

= 3.6V

V

OUT

= 1.8V

LOAD STEP 0mA TO 600mA

Burst Mode OPERATION

35451fb

5

Parameter Name	Attribute value
EU restricts the use of certain hazardous substances	Compliant
ECCN (US)	EAR99
Part Status	Active
HTS	8542.39.00.01
Type	Synchronous Step Down
Output Type	Adjustable
Switching Frequency (kHz)	2700
Switching Regulator	Yes
Number of Outputs	3
Output Voltage (V)	0.6 to 5.5
Maximum Output Current (A)	0.8
Minimum Input Voltage (V)	2.25
Maximum Input Voltage (V)	5.5
Operating Supply Voltage (V)	2.25 to 5.5
Typical Quiescent Current (uA)	310
Line Regulation	0.15%/V
Load Regulation	0.5%(Typ)
Efficiency (%)	95
Minimum Operating Temperature (°C)	-40
Maximum Operating Temperature (°C)	125
Supplier Temperature Grade	Extended
Packaging	Tape and Reel
Pin Count	16
Standard Package Name	QFN
Supplier Package	QFN EP
Mounting	Surface Mount
Package Height	0.75(Max)
Package Length	3
Package Width	3
PCB changed	16
Lead Shape	No Lead

	LTC3545EUD#TRPBF	LTC3545EUD#PBF	LTC3545EUD-1#PBF	LTC3545EUD-1#TRPBF	LTC3545IUD#PBF	LTC3545IUD#TRPBF
Description	Conv DC-DC 2.25V to 5.5V Synchronous Step Down Triple-Out 0.6V to 5.5V 0.8A Automotive 16-Pin QFN EP T/R	Conv DC-DC 2.25V to 5.5V Synchronous Step Down Triple-Out 0.6V to 5.5V 0.8A Automotive 16-Pin QFN EP Tube	Conv DC-DC 2.25V to 5.5V Synchronous Step Down Triple-Out 0.6V to 5.5V 0.8A 16-Pin QFN EP Tube	Conv DC-DC 2.25V to 5.5V Synchronous Step Down Triple-Out 0.6V to 5.5V 0.8A 16-Pin QFN EP T/R	Conv DC-DC 2.25V to 5.5V Synchronous Step Down Triple-Out 0.6V to 5.5V 0.8A Automotive 16-Pin QFN EP Tube	Conv DC-DC 2.25V to 5.5V Synchronous Step Down Triple-Out 0.6V to 5.5V 0.8A Automotive 16-Pin QFN EP T/R
EU restricts the use of certain hazardous substances	Compliant	Compliant	Compliant	Compliant	Compliant	Compliant
ECCN (US)	EAR99	EAR99	EAR99	EAR99	EAR99	EAR99
Part Status	Active	Active	Active	Active	Active	Active
Type	Synchronous Step Down	Synchronous Step Down	Synchronous Step Down	Synchronous Step Down	Synchronous Step Down	Synchronous Step Down
Output Type	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable	Adjustable
Switching Frequency (kHz)	2700	2700	2700	2700	2700	2700
Switching Regulator	Yes	Yes	Yes	Yes	Yes	Yes
Number of Outputs	3	3	3	3	3	3
Output Voltage (V)	0.6 to 5.5	0.6 to 5.5	0.6 to 5.5	0.6 to 5.5	0.6 to 5.5	0.6 to 5.5
Maximum Output Current (A)	0.8	0.8	0.8	0.8	0.8	0.8
Minimum Input Voltage (V)	2.25	2.25	2.25	2.25	2.25	2.25
Maximum Input Voltage (V)	5.5	5.5	5.5	5.5	5.5	5.5
Operating Supply Voltage (V)	2.25 to 5.5	2.25 to 5.5	2.25 to 5.5	2.25 to 5.5	2.25 to 5.5	2.25 to 5.5
Typical Quiescent Current (uA)	310	310	310	310	310	310
Line Regulation	0.15%/V	0.15%/V	0.15%/V	0.15%/V	0.15%/V	0.15%/V
Load Regulation	0.5%(Typ)	0.5%(Typ)	0.5%(Typ)	0.5%(Typ)	0.5%(Typ)	0.5%(Typ)
Efficiency (%)	95	95	95	95	95	95
Minimum Operating Temperature (°C)	-40	-40	-40	-40	-40	-40
Maximum Operating Temperature (°C)	125	125	125	125	125	125
Supplier Temperature Grade	Extended	Extended	Extended	Extended	Industrial	Industrial
Packaging	Tape and Reel	Tube	Tube	Tape and Reel	Tube	Tape and Reel
Pin Count	16	16	16	16	16	16
Standard Package Name	QFN	QFN	QFN	QFN	QFN	QFN
Supplier Package	QFN EP	QFN EP	QFN EP	QFN EP	QFN EP	QFN EP
Mounting	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount	Surface Mount
Package Height	0.75(Max)	0.75(Max)	0.75(Max)	0.75(Max)	0.75(Max)	0.75(Max)
Package Length	3	3	3	3	3	3
Package Width	3	3	3	3	3	3
PCB changed	16	16	16	16	16	16
Lead Shape	No Lead	No Lead	No Lead	No Lead	No Lead	No Lead
HTS	8542.39.00.01	8542.39.00.01	8542.39.00.01	8542.39.00.01	8542.39.00.01	-

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