LT3467AIDDB datasheet, PDF - EEWORLD Datasheet

FEATURES

n

LT3467/LT3467A

1.1A Step-Up DC/DC

Converter with

Integrated Soft-Start

DESCRIPTION

The LT

®

3467/LT3467A switching regulators combine a

42V, 1.1A switch with a soft-start function. Pin compatible

with the LT1930, its low V

CESAT

bipolar switch enables the

device to deliver high current outputs in a small footprint.

The LT3467 switches at 1.3MHz, allowing the use of tiny,

low cost and low height inductors and capacitors. The

LT3467A switches at 2.1MHz, allowing the use of even

smaller components. High inrush current at start-up is

eliminated using the programmable soft-start function.

A single external capacitor sets the current ramp rate. A

constant frequency current mode PWM architecture results

in low, predictable output noise that is easy to ﬁlter.

The high voltage switch on the LT3467/LT3467A is rated

at 42V, making the devices ideal for boost converters up

to 40V as well as SEPIC and ﬂyback designs. The LT3467

can generate 5V at up to 540mA from a 3.3V supply or

5V at 450mA from four alkaline cells in a SEPIC design.

The LT3467A can generate 5V at up to 430mA from a 3.3V

supply or 15V at 135mA from a 3.3V supply. The LT3467/

LT3467A are available in a low proﬁle (1mm) 6-lead SOT-23

package and tiny 3mm

×

2mm DFN package.

L,

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

Technology Corporation. ThinSOT is a trademark of Linear Technology Corporation. All other

trademarks are the property of their respective owners.

1.3MHz Switching Frequency (LT3467)

2.1MHz Switching Frequency (LT3467A)

Low V

CESAT

Switch: 330mV at 1.1A

High Output Voltage: Up to 40V

Wide Input Range: 2.4V to 16V

Dedicated Soft-Start Pin

5V at 540mA from 3.3V Input (LT3467)

5V at 430mA from 3.3V Input (LT3467A)

12V at 270mA from 5V Input (LT3467)

12V at 260mA from 5V Input (LT3467A)

Uses Small Surface Mount Components

Low Shutdown Current: <1μA

Pin-for-Pin Compatible with the LT1930 and LT1613

Low Proﬁle (1mm) ThinSOT™ Package

Low Proﬁle (0.75mm) 8-Lead (3mm

×

2mm)

DFN Package

APPLICATIONS

n

Digital Cameras

White LED Power Supplies

Cellular Phones

Medical Diagnostic Equipment

Local 5V or 12V Supplies

TFT-LCD Bias Supplies

xDSL Power Supplies

TYPICAL APPLICATION

95

Efﬁciency

90

V

OUT

5V

765mA AT V

IN

= 4.2V,

540mA AT V

IN

= 3.3V,

360mA AT V

IN

= 2.6V

3.3pF

85

EFFICIENCY (%)

80

75

70

65

60

55

3467 TA01a

Single Li-Ion Cell to 5V Boost Converter

V

IN

2.6V TO

4.2V

4.7μF

OFF ON

V

IN

SHDN

LT3467

SS

GND

2.7μH

V

IN

= 4.2V

V

IN

= 3.3V

V

IN

= 2.6V

SW

402k

FB

133k

15μF

0.047μF

50

100 200 300 400 500 600 700 800 900

I

OUT

(mA)

3467 TA01b

3467afe

1

LT3467/LT3467A

ABSOLUTE MAXIMUM RATINGS

(Note 1)

V

IN

Voltage ................................................................16V

SW Voltage ................................................ –0.4V to 42V

FB Voltage ................................................................2.5V

Current Into FB Pin .............................................. ±1mA

SHDN

Voltage ......................................................... 16V

Maximum Junction Temperature ......................... 125°C

Operating Junction Temperature Range (Note 2)

E Grade ................................................ –40°C to 85°C

I Grade ............................................... –40°C to 125°C

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

Lead Temperature (Soldering, 10 sec)

TSOT................................................................. 300°C

PIN CONFIGURATION

TOP VIEW

FB 1

GND 2

SW 3

SW 4

9

8

7

6

5

SHDN

SS

V

IN

GND

SW 1

GND 2

FB 3

TOP VIEW

6 V

IN

5 SS

4

SHDN

DDB PACKAGE

8-LEAD (3mm 2mm) PLASTIC DFN

T

JMAX

= 125°C,

θ

JA

= 80°C/W

EXPOSED PAD (PIN 9) IS GND, MUST BE SOLDERED TO PCB

S6 PACKAGE

6-LEAD PLASTIC TSOT-23

T

JMAX

= 125°C,

θ

JA

= 165°C/W,

θ

JC

= 102°C/W

ORDER INFORMATION

LEAD FREE FINISH

LT3467EDDB#PBF

LT3467IDDB#PBF

LT3467AEDDB#PBF

LT3467AIDDB#PBF

LT3467IS6#PBF

LT3467ES6#PBF

LT3467AES6#PBF

LT3467AIS6#PBF

LEAD BASED FINISH

LT3467EDDB

LT3467IDDB

LT3467AEDDB

LT3467AIDDB

LT3467IS6

LT3467ES6

LT3467AES67

LT3467AIS67

TAPE AND REEL

LT3467EDDB#TRPBF

LT3467IDDB#TRPBF

LT3467AEDDB#TRPBF

LT3467AIDDB#TRPBF

LT3467IS6#TRPBF

LT3467ES6#TRPBF

LT3467AES6#TRPBF

LT3467AIS6#TRPBF

TAPE AND REEL

LT3467EDDB#TR

LT3467IDDB#TR

LT3467AEDDB#TR

LT3467AIDDB#TR

LT3467IS6#TR

LT3467ES6#TR

LT3467AES6#TR

LT3467AIS67#TR

PART MARKING*

LCPX

LCKD

LTACH

LTBCC

PART MARKING*

LCPX

LCKD

LTACH

LTBCC

PACKAGE DESCRIPTION

8-Lead (3mm

×

2mm) Plastic DFN

8-Lead (3mm

×

2mm) Plastic DFN

8-Lead (3mm

×

2mm) Plastic DFN

8-Lead (3mm

×

2mm) Plastic DFN

6-Lead Plastic TSOT-23

PACKAGE DESCRIPTION

8-Lead (3mm

×

2mm) Plastic DFN

8-Lead (3mm

×

2mm) Plastic DFN

8-Lead (3mm

×

2mm) Plastic DFN

8-Lead (3mm

×

2mm) Plastic DFN

6-Lead Plastic TSOT-23

TEMPERATURE RANGE

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

–40°C to 125°C

TEMPERATURE RANGE

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

–40°C to 125°C

–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/

3467afe

2

LT3467/LT3467A

ELECTRICAL CHARACTERISTICS

PARAMETER

Minimum Operating Voltage

Maximum Operating Voltage

Feedback Voltage

FB Pin Bias Current

Quiescent Current

Quiescent Current in Shutdown

Reference Line Regulation

Switching Frequency

(Note 3)

V

SHDN

= 2.4V, Not Switching

V

SHDN

= 0.5V, V

IN

= 3V

2.6V ≤ V

IN

≤ 16V

LT3467

LT3467A

LT3467

LT3467A

At Minimum Duty Cycle

At Maximum Duty Cycle (Note 4)

I

SW

= 1.1A

V

SW

= 5V

2.4

0.5

V

SHDN

= 3V

V

SHDN

= 0V

V

SS

= 0.5V

2

16

0

3

32

0.1

4.5

1

1.6

88

87

82

78

1.4

0.8

l

The

l

denotes the speciﬁcations which apply over the full operating

temperature range, otherwise speciﬁcations are at T

A

= 25°C. V

IN

= 3V, V

SHDN

= V

IN

unless otherwise noted. Speciﬁcations are for both

the LT3467 and LT3467A unless otherwise noted.

CONDITIONS

MIN

TYP

2.2

1.230

1.220

1.255

10

1.2

0.01

1.3

2.1

94

88

10

1.8

1.2

330

0.01

2.5

1.9

500

1

MAX

2.4

16

1.270

1.280

50

2

1

0.05

1.6

2.7

UNITS

V

nA

mA

μA

%/V

MHz

%

A

mV

μA

V

μA

l

Maximum Duty Cycle

Minimum Duty Cycle

Switch Current Limit

Switch V

CESAT

Switch Leakage Current

SHDN

Input Voltage High

SHDN

Input Voltage Low

SHDN

Pin Bias Current

SS Charging Current

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 LT3467E/LT3467AE are guaranteed to meet performance

speciﬁcations from 0°C to 85°C, junction temperature. Speciﬁcations over

the –40°C to 85°C operating junction temperature range are assured by

design, characterization and correlation with statistical process controls.

The LT3467I/LT3467AI are guaranteed over the full –40°C to 125°C

operating junction temperature range.

Note 3:

Current ﬂows out of the pin.

Note 4:

See Typical Performance Characteristics for guaranteed current

limit vs duty cycle.

3467afe

3

LT3467/LT3467A

TYPICAL PERFORMANCE CHARACTERISTICS

Quiescent Current vs Temperature

1.6

1.4

1.2

I

SHDN

(μA)

1.0

I

Q

(mA)

0.8

0.6

0.4

0.2

0

–40 –25 –10 5

20 35 50 65 80 95 110 125

TEMPERATURE (°C)

3467 G01

FB Pin Voltage vs Temperature

1.26

1.25

1.24

V

FB

(V)

1.23

1.22

1.21

1.20

–40 –25 –10 5

140

120

100

80

60

40

20

0

SHDN

Current vs

SHDN

Voltage

T

A

= 25°C

20 35 50 65 80 95 110 125

TEMPERATURE (°C)

3467 G02

0

2

4

6

10 12

V

SHDN

(V)

8

14

16

18

3467 G03

Current Limit vs Duty Cycle

2.0

1.8

1.6

1.4

I

LIM

(A)

1.2

1.0

0.8

0.6

0.4

0.2

0

10

20

30

40

50 60

DC (%)

70

80

90

GUARANTEED

V

CESAT

100mV/DIV

TYPICAL

T

A

= 25°C

Switch Saturation Voltage

vs Switch Current

2.50

2.25

OSCILLATOR FREQUENCY (MHz)

2.00

1.75

1.50

1.25

1.00

0.75

0.50

0.25

3467 G05

Oscillator Frequency

vs Temperature

LT3467A

T

A

= 25°C

T

A

= 85°C

LT3467

T

A

= –40°C

SW CURRENT 200mA/DIV

0

–50

–25

0

25

50

75

100

3467 G06

TEMPERATURE (°C)

3467 G04

Soft-Start Current

vs Soft-Start Voltage

6

5

SWITCH CURRENT (A)

4

I

SS

(μA)

3

2

1

0

T

A

= 25°C

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

50 100 150 200 250 300 350 400 450 500

V

SS

(mV)

3467 G07

Peak Switch Current

vs Soft-Start Voltage

T

A

= 25°C

V

SHDN

2V/DIV

Start-Up Waveform

(Figure 2 Circuit)

V

OUT

1V/DIV

I

SUPPLY

0.5A/DIV

0

50 100 150 200 250 300 350 400 450 500

V

SS

(mV)

3467 G08

0.5ms/DIV

3467 G09

3467afe

4

LT3467/LT3467A

PIN FUNCTIONS

(DFN/TSOT)

FB (Pin 1/Pin 3):

Feedback Pin. Reference voltage is 1.255V.

Connect resistive divider tap here. Minimize trace area at

FB. Set V

OUT

= 1.255V(1 + R1/R2).

GND (Pins 2, 5, 9/Pin 2):

Ground. Tie directly to local

ground plane.

SW (Pins 3, 4/Pin 1):

Switch Pin. (Collector of internal

NPN power switch) Connect inductor/diode here and

minimize the metal trace area connected to this pin to

minimize EMI.

V

IN

(Pin 6/Pin 6):

Input Supply Pin. Must be locally

bypassed.

SS (Pin 7/Pin 5):

Soft-Start Pin. Place a soft-start capacitor

here. Upon start-up, 4μA of current charges the capacitor

to 1.255V. Use a larger capacitor for slower start-up. Leave

ﬂoating if not in use.

SHDN

(Pin 8/Pin 4):

Shutdown Pin. Tie to 2.4V or more

to enable device. Ground to shut down.

BLOCK DIAGRAM

250k

SS

V

IN

1.255V

REFERENCE

+

A1

SW

COMPARATOR

–

V

OUT

R1 (EXTERNAL)

FB

R2 (EXTERNAL)

R

C

RAMP

GENERATOR

SHUTDOWN

SHDN

FB

1.3MHz

OSCILLATOR*

GND

3467 F01

Figure 1. Block Diagram

+

*2.1MHz FOR LT3467A

–

A2

R

S

Q

DRIVER

Q1

+

0.01Ω

–

3467afe

5

LT3467AIDDB

LT3467AIDDB Overview

Preview

Recommended Resources