LT3680IDD#PBF datasheet, PDF - EEWORLD Datasheet

LT3680

36V, 3.5A, 2.4MHz

Step-Down Switching Regulator

with 75µA Quiescent Current

FEATURES

■

DESCRIPTION

The LT

®

3680 is an adjustable frequency (200kHz to

2.4MHz) monolithic buck switching regulator that accepts

input voltages up to 36V. A high efﬁciency 95m switch

is included on the die along with a boost Schottky diode

and the necessary oscillator, control, and logic circuitry.

Current mode topology is used for fast transient response

and good loop stability. Low ripple Burst Mode

®

operation

maintains high efﬁciency at low output currents while

keeping output ripple below 15mV in a typical application.

In addition, the LT3680 can further enhance low output

current efﬁciency by drawing bias current from the output

when V

OUT

is above 3V. Shutdown reduces input supply

current to less than 1μA while a resistor and capacitor on

the RUN/SS pin provide a controlled output voltage ramp

(soft-start). A power good ﬂag signals when V

OUT

reaches

91% of the programmed output voltage. The LT3680 is

available in 10-Pin MSOP and 3mm

×

3mm DFN packages

with exposed pads for low thermal resistance.

L,

LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of

Linear Technology Corporation.

Burst Mode is a registered trademark of Linear Technology

Corporation.

All other trademarks are the property of their respective owners.

■

Wide Input Voltage Range: 3.6V to 36V

3.5A Maximum Output Current

Low Ripple (<15mV

P-P

) Burst Mode

®

Operation:

I

Q

= 75μA at 12V

IN

to 3.3V

OUT

Adjustable Switching Frequency: 200kHz to 2.4MHz

Low Shutdown Current: I

Q

< 0.5μA

Integrated Boost Diode

Synchronizable Between 250kHz to 2MHz

Power Good Flag

Saturating Switch Design: 95m On-Resistance

0.790V Feedback Reference Voltage

Output Voltage: 0.79V to 30V

Thermal Protection

Soft-Start Capability

Small 10-Pin Thermally Enhanced MSOP and

(3mm

×

3mm) DFN Packages

APPLICATIONS

■

Automotive Battery Regulation

Power for Portable Products

Distributed Supply Regulation

Industrial Supplies

Wall Transformer Regulation

TYPICAL APPLICATION

5V Step-Down Converter

V

IN

6.3V TO 36V

V

IN

OFF ON

15k

10μF

680pF

63.4k

V

C

RT

PG

SYNC

536k

GND

FB

100k

47μF

50

0

0.5

2

1.5

1

2.5

OUTPUT CURRENT (A)

3

3.5

3680 G01

Efﬁciency

V

OUT

5V

3.5A

100

V

IN

= 12V

90

EFFICIENCY (%)

V

IN

= 34V

80

V

IN

= 24V

BD

BOOST

0.47μF 4.7μH

LT3680

SW

RUN/SS

70

60

V

OUT

= 5V

L = 4.7μH

f = 600kHz

3680 TA01a

3680fb

1

LT3680

ABSOLUTE MAXIMUM RATINGS

(Note 1)

V

IN

, RUN/SS Voltage .................................................36V

BOOST Pin Voltage ...................................................56V

BOOST Pin Above SW Pin.........................................30V

FB, RT, V

C

Voltage .......................................................5V

PG, BD, SYNC Voltage ..............................................30V

Operating Junction Temperature Range (Note 2)

LT3680E............................................. –40°C to 125°C

LT3680I.............................................. –40°C to 125°C

LT3680H ............................................ –40°C to 150°C

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

Lead Temperature (Soldering, 10 sec)

(MSE Only) ....................................................... 300°C

PIN CONFIGURATION

TOP VIEW

BD

BOOST

SW

V

IN

RUN/SS

1

2

3

4

5

11

10 RT

9 V

C

8 FB

7 PG

6 SYNC

TOP VIEW

BD

BOOST

SW

V

IN

RUN/SS

1

2

3

4

5

10

9

8

7

6

RT

V

C

FB

PG

SYNC

11

DD PACKAGE

10-LEAD (3mm 3mm) PLASTIC DFN

θ

JA

= 45°C/W,

θ

JC

= 10°C/W

EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB

MSE PACKAGE

10-LEAD PLASTIC MSOP

θ

JA

= 45°C/W,

θ

JC

= 10°C/W

EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB

ORDER INFORMATION

LEAD FREE FINISH

LT3680EDD#PBF

LT3680IDD#PBF

LT3680EMSE#PBF

LT3680IMSE#PBF

LT3680HMSE#PBF

TAPE AND REEL

LT3680EDD#TRPBF

LT3680IDD#TRPBF

LT3680EMSE#TRPBF

LT3680IMSE#TRPBF

LT3680HMSE#TRPBF

PART MARKING*

LCYK

LTCYM

PACKAGE DESCRIPTION

10-Lead (3mm

×

3mm) Plastic DFN

10-Lead (3mm

×

3mm) Plastic DFN

10-Lead Plastic MSOP

TEMPERATURE RANGE

–40°C to 125°C

–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.

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/

3680fb

2

LT3680

ELECTRICAL CHARACTERISTICS

PARAMETER

Minimum Input Voltage

Quiescent Current from V

IN

The

●

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= 10V, V

RUN/SS

= 10V V

BOOST

= 15V, V

BD

= 3.3V unless otherwise

noted. (Note 2)

CONDITIONS

●

MIN

Quiescent Current from BD

V

RUN/SS

= 0.2V

V

BD

= 3V, Not Switching

V

BD

= 0, Not Switching

V

RUN/SS

= 0.2V

V

BD

= 3V, Not Switching

V

BD

= 0, Not Switching

●

Minimum Bias Voltage (BD Pin)

Feedback Voltage

●

780

775

TYP

3

0.01

30

120

0.01

90

1

2.7

790

10

0.002

500

2000

60

5.3

2.0

2.45

1.1

230

60

5.4

335

0.02

1.5

35

5

MAX

3.6

0.5

65

160

0.5

130

5

3

800

805

40

0.01

UNITS

V

μA

V

mV

nA

%/V

μMho

μA

A/V

V

MHz

kHz

nS

A

mV

μA

V

mA

μA

V

mV

μA

V

μA

FB Pin Bias Current (Note 3)

FB Voltage Line Regulation

Error Amp g

m

Error Amp Gain

V

C

Source Current

V

C

Sink Current

V

C

Pin to Switch Current Gain

V

C

Clamp Voltage

Switching Frequency

V

FB

= 0.8V, V

C

= 0.4V

4V < V

IN

< 36V

●

R

T

= 8.66k

R

T

= 29.4k

R

T

= 187k

●

2.2

1.0

200

4.6

Minimum Switch Off-Time

Switch Current Limit

Switch V

CESAT

Boost Schottky Reverse Leakage

Minimum Boost Voltage (Note 4)

BOOST Pin Current

RUN/SS Pin Current

RUN/SS Input Voltage High

RUN/SS Input Voltage Low

PG Threshold Offset from Feedback Voltage

PG Hysteresis

PG Leakage

PG Sink Current

SYNC Low Threshold

SYNC High Threshold

SYNC Pin Bias Current

Duty Cycle = 5%

I

SW

= 3.5A

V

BOOST

= 10V, V

BD

= 0V

●

2.7

1.25

260

150

6.0

2

2.0

50

8

2.5

I

SW

= 1A

V

RUN/SS

= 2.5V

0.2

V

FB

Rising

V

PG

= 5V

V

PG

= 0.4V

●

200

0.5

65

10

0.1

800

1

0.7

V

SYNC

= 0V

0.1

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 LT3680E is guaranteed to meet performance speciﬁcations

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

temperature range are assured by design, characterization and correlation

with statistical process controls. The LT3680I speciﬁcations are

guaranteed over the –40°C to 125°C temperature range. The LT3680H

speciﬁcations are guaranteed over the –40°C to 150°C operating

temerature range. High junction temperatures degrade operating lifetimes.

Operating lifetime is derated at junction temperatures greater than 125°C.

Note 3:

Bias current ﬂows out of the FB pin.

Note 4:

This is the minimum voltage across the boost capacitor needed to

guarantee full saturation of the switch.

3680fb

3

LT3680

TYPICAL PERFORMANCE CHARACTERISTICS

Efﬁciency

100

V

IN

= 12V

90

EFFICIENCY (%)

V

IN

= 34V

80

V

IN

= 24V

90

V

IN

= 12V

EFFICIENCY (%)

90

2.5

TOTAL POWER LOSS (W)

100

T

A

= 25°C unless otherwise noted.

Efﬁciency

100

3.0

Efﬁciency

80

V

IN

= 34V

V

IN

= 24V

80

2.0

70

V

IN

= 12V

V

OUT

= 5V

L = 4.7μH

f = 600kHz

0

0.5

2

1.5

1

2.5

OUTPUT CURRENT (A)

3

3.5

3680 G03

1.5

60

V

OUT

= 5V

L = 4.7μH

f = 600kHz

0

0.5

2

1.5

1

2.5

OUTPUT CURRENT (A)

3

3.5

3680 G01

60

50

V

OUT

= 3.3V

L = 3.3μH

f = 600kHz

0

0.5

2

1.5

1

2.5

OUTPUT CURRENT (A)

3

3.5

3680 G02

60

1.0

50

0.5

No Load Supply Current

130

110

SUPPLY CURRENT (μA)

90

70

50

30

10

0

5

15

10

20

25

INPUT VOLTAGE (V)

30

35

3680 G04

No Load Supply Current

V

OUT

= 3.3V

400

CATCH DIODE: DIODES, INC. PDS360

350

300

250

200

150

100

50

0

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3680 G05

Maximum Load Current

5.5

TYPICAL

V

IN

= 12V

V

OUT

= 3.3V

LOAD CURRENT (A)

INCREASED SUPPLY

CURRENT DUE TO CATCH

DIODE LEAKAGE AT

HIGH TEMPERATURE

5.0

4.5

MINIMUM

4.0

3.5

3.0

2.5

5

10

20

25

15

INPUT VOLTAGE (V)

30

3680 G06

V

OUT

= 3.3V

T

A

= 25°C

L = 4.7μH

f = 600kHz

Maximum Load Current

5.5

TYPICAL

6.0

5.5

5.0

4.5

4.0

3.5

Switch Current Limit

6.5

6.0

SWITCH CURRENT LIMIT (A)

5.5

5.0

4.5

4.0

3.5

3.0

2.5

3.0

Switch Current Limit

SWITCH CURRENT LIMIT(A)

5.0

LOAD CURRENT (A)

DUTY CYCLE = 10 %

4.5

MINIMUM

4.0

V

OUT

= 5V

T

A

= 25°C

L = 4.7μH

f = 600kHz

5

10

20

25

15

INPUT VOLTAGE (V)

30

3680 G07

DUTY CYCLE = 90 %

3.5

3.0

0

20

60

40

DUTY CYCLE (%)

80

100

3680 G08

2.0

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3680 G09

3680fb

4

LT3680

TYPICAL PERFORMANCE CHARACTERISTICS

Switch Voltage Drop

700

600

BOOST PIN CURRENT (mA)

VOLTAGE DROP (mV)

500

400

300

200

100

0

1

2

4

3

SWITCH CURRENT (A)

5

3680 G10

T

A

= 25°C unless otherwise noted.

Boost Pin Current

120

105

90

75

60

45

30

15

0

1

2

3

SWITCH CURRENT (A)

4

5

3680 G11

Feedback Voltage

840

FEEDBACK VOLTAGE (mV)

820

800

780

760

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3680 G12

Switching Frequency

1.20

1.15

1.10

FREQUENCY (MHz)

1.05

1.00

0.95

0.90

0.85

0.80

–50 –25

0

25 50 75 100 125 150

TEMPERATURE (°C)

3680 G13

Frequency Foldback

1200

1000

800

600

400

200

0

100 200 300 400 500 600 700 800 900

FB PIN VOLTAGE (mV)

3680 G14

Minimum Switch On-Time

140

MINIMUM SWITCH ON TIME (ns)

120

100

80

60

40

20

0

–50 –25

SWITCHING FREQUENCY (kHz)

0

25 50 75 100 125 150

TEMPERATURE (°C)

3680 G15

Soft-Start

7

6

SWITCH CURRENT LIMIT (A)

5

4

3

2

1

0

0.5

2.5

2

1.5

RUN/SS PIN VOLTAGE (V)

1

3

3.5

3680 G16

RUN/SS Pin Current

12

10

BOOST DIODE V

F

(V)

0

20

30

15

25

10

RUN/SS PIN VOLTAGE (V)

35

3680 G17

Boost Diode

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

RUN/SS PIN CURRENT (μA)

8

6

4

2

0

5

0

0.5

1.0

1.5

BOOST DIODE CURRENT (A)

2.0

3680 G18

3680fb

5

Parameter Name	Attribute value
Output voltage (minimum/fixed)	0.79V
Output voltage (maximum)	30V
Can output current	3.5A
Switching operating frequency	230kHz ~ 2.45MHz
Output type	Adjustable
Number of output voltage channels	1
Minimum input voltage	3.6V
Maximum input voltage	36V
Power topology	Buck
Synchronous rectification or not	No
Function type	Step-Down
Output configuration	Positive

	LT3680IDD#PBF	LT3680EDD#PBF	LT3680EMSE#PBF	LT3680HMSE#PBF
Description	Output current: 3.5A Switch operating frequency: 230kHz ~ 2.45MHz Output type: Adjustable Number of output voltage channels: 1 Function type: Step-Down Output configuration: Positive 36V, 3.5A, 2.4MHz step-down type with 75μA quiescent current switching regulator	IC reg buck adj 3.5A 10dfn	Output current: 3.5A Switch operating frequency: 230kHz ~ 2.45MHz Output type: Adjustable Number of output voltage channels: 1 Function type: Step-Down Output configuration: Positive	Output current: 3.5A Switch operating frequency: 230kHz ~ 2.45MHz Output type: Adjustable Number of output voltage channels: 1 Function type: Step-Down Output configuration: Positive
Minimum input voltage	3.6V	-	3.6 V	3.6 V
Maximum input voltage	36V	-	36 V	36 V

LT3680IDD#PBF

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