LT3467EDDB#TRM_技术文档

LT3467/LT3467A

1.1A Step-Up DC/DC

Converter with

Integrated Soft-Start

FEATURES

DESCRIPTION

The LT^®3467/LT3467A switching regulators combine a

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

n

1.3MHz Switching Frequency (LT3467)

n

2.1MHz Switching Frequency (LT3467A)

n

Low V

Switch: 330mV at 1.1A

with the LT1930, its low V

bipolar switch enables the

CESAT

n

High Output Voltage: Up to 40V

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

constantfrequencycurrentmodePWMarchitectureresults

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

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

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/

LT3467Aareavailableinalowproﬁle(1mm)6-leadSOT-23

package and tiny 3mm × 2mm DFN package.

™

Low Proﬁle (1mm) ThinSOT Package

Low Proﬁle (0.75mm) 8-Lead (3mm × 2mm)

DFN Package

APPLICATIONS

n

Digital Cameras

n

White LED Power Supplies

n

Cellular Phones

n

Medical Diagnostic Equipment

L, LT, LTC and LTM 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.

n

Local 5V or 12V Supplies

n

TFT-LCD Bias Supplies

n

xDSL Power Supplies

TYPICAL APPLICATION

Efﬁciency

95

Single Li-Ion Cell to 5V Boost Converter

90

V

= 4.2V

2.7μH

IN

V

85

80

75

70

65

60

55

50

IN

V

OUT

5V

2.6V TO

4.2V

V

= 3.3V

IN

V

= 2.6V

765mA AT V = 4.2V,

IN

4.7μF

402k

133k

540mA AT V = 3.3V,

V

SW

IN

360mA AT V = 2.6V

SHDN

OFF ON

3.3pF

LT3467

SS

FB

GND

15μF

0.047μF

3467 TA01a

800

900

100

300 400 500

700

200

600

I

(mA)

OUT

3467 TA01b

3467afd

1

LT3467/LT3467A

ABSOLUTE MAXIMUM RATINGS ^{(Note 1)}

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

Operating Temperature Range (Note 2)

IN

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

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

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

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

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

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

GND

SW

1

2

3

4

8

7

6

5

SHDN

SS

SW 1

GND 2

FB 3

6 V

IN

9

5 SS

V_IN

4 SHDN

SW

GND

S6 PACKAGE

6-LEAD PLASTIC TSOT-23

DDB PACKAGE

8-LEAD (3mm s 2mm) PLASTIC DFN

T

= 125°C, θ = 165°C/W, θ = 102°C/W

JA JC

JMAX

T

= 125°C, θ = 80°C/W

JA

JMAX

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

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

TAPE AND REEL

PART MARKING*

LCPX

PACKAGE DESCRIPTION

TEMPERATURE RANGE

–40°C to 85°C

LT3467EDDB#TRPBF

LT3467IDDB#TRPBF

LT3467AEDDB#TRPBF

LT3467AIDDB#TRPBF

LT3467IS6#TRPBF

LT3467ES6#TRPBF

LT3467AES6#TRPBF

LT3467AIS6#TRPBF

TAPE AND REEL

8-Lead (3mm × 2mm) Plastic DFN

6-Lead Plastic TSOT-23

LCPX

–40°C to 125°C

–40°C to 85°C

LCKD

–40°C to 125°C

–40°C to 85°C

LTACH

6-Lead Plastic TSOT-23

LTBCC

6-Lead Plastic TSOT-23

–40°C to 85°C

LTBCC

6-Lead Plastic TSOT-23

–40°C to 125°C

TEMPERATURE RANGE

–40°C to 85°C

PART MARKING*

LCPX

PACKAGE DESCRIPTION

LT3467EDDB#TR

LT3467IDDB#TR

8-Lead (3mm × 2mm) Plastic DFN

6-Lead Plastic TSOT-23

LT3467IDDB

LCPX

–40°C to 125°C

–40°C to 85°C

LT3467AEDDB

LT3467AIDDB

LT3467AEDDB#TR

LT3467AIDDB#TR

LT3467IS6#TR

LCKD

–40°C to 125°C

–40°C to 85°C

LT3467IS6

LTACH

LT3467ES6

LT3467ES6#TR

LTACH

6-Lead Plastic TSOT-23

LT3467AES67

LT3467AES6#TR

LTBCC

6-Lead Plastic TSOT-23

–40°C to 85°C

LT3467AIS67

LT3467AIS67#TR

LTBCC

6-Lead Plastic TSOT-23

–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/

3467afd

2

LT3467/LT3467A

ELECTRICAL CHARACTERISTICS ^Thel 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_INunless otherwise noted. Speciﬁcations are for both

the LT3467 and LT3467A unless otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

MAX

2.4

UNITS

Minimum Operating Voltage

Maximum Operating Voltage

Feedback Voltage

2.2

V

16

1.230

1.220

1.255

1.270

1.280

V

l

FB Pin Bias Current

(Note 3)

10

50

2

nA

mA

μA

Quiescent Current

V

SHDN

V

SHDN

= 2.4V, Not Switching

1.2

Quiescent Current in Shutdown

Reference Line Regulation

Switching Frequency

= 0.5V, V = 3V

0.01

1

IN

2.6V ≤ V ≤ 16V

0.05

%/V

IN

LT3467

LT3467A

1

1.6

1.3

2.1

1.6

2.7

MHz

l

Maximum Duty Cycle

LT3467

LT3467A

88

87

82

78

94

88

%

l

Minimum Duty Cycle

Switch Current Limit

10

%

At Minimum Duty Cycle

At Maximum Duty Cycle (Note 4)

1.4

0.8

1.8

1.2

2.5

1.9

A

Switch V

I

= 1.1A

= 5V

330

500

1

mV

μA

V

CESAT

SW

Switch Leakage Current

SHDN Input Voltage High

SHDN Input Voltage Low

SHDN Pin Bias Current

V

0.01

SW

2.4

0.5

V

= 3V

= 0V

16

0

32

0.1

μA

SHDN

SS Charging Current

V

= 0.5V

2

3

4.5

μA

SS

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 3: Current ﬂows out of the pin.

Note 4: See Typical Performance Characteristics for guaranteed current

limit vs duty cycle.

Note 2: The LT3467E/LT3467AE are 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 LT3467IS6 is guaranteed

and tested over the full –40°C to 125°C operating temperature range.

3467afd

3

LT3467/LT3467A

TYPICAL PERFORMANCE CHARACTERISTICS

Quiescent Current vs Temperature

FB Pin Voltage vs Temperature

SHDN Current vs SHDN Voltage

1.26

1.25

1.24

1.23

1.22

1.21

1.20

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

140

120

100

80

T

= 25°C

A

60

40

20

0

–25 –10

5

20 35 50 65 80

TEMPERATURE (°C)

125

95 110

–25 –10

5

20 35 50 65 80

TEMPERATURE (°C)

125

95 110

–40

0

2

4

6

12 14 16 18

8

10

V

SHDN

(V)

3467 G03

3467 G02

3467 G01

Switch Saturation Voltage vs

Switch Current

Oscillator Frequency vs

Temperature

Current Limit vs Duty Cycle

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

2.50

2.25

2.00

1.75

1.50

1.25

1.00

0.75

0.50

0.25

0

T

= 25°C

A

LT3467A

TYPICAL

T

A

= 25°C

T

A

= 85°C

V

CESAT

LT3467

GUARANTEED

100mV/DIV

T

A

= –40°C

3467 G05

–25

0

25

50

75

10

50

70 80

–50

100

20 30 40

60

90

SW CURRENT 200mA/DIV

DC (%)

TEMPERATURE (°C)

3467 G04

3467 G06

Soft-Start Current vs Soft-Start

Voltage

Peak Switch Current vs Soft-Start

Voltage

Start-Up Waveform

(Figure 2 Circuit)

6

5

4

3

2

1

0

2.0

1.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

T

= 25°C

T = 25°C

A

V

SHDN

2V/DIV

V

OUT

1V/DIV

I

SUPPLY

0.5A/DIV

3467 G09

0

50 100 150 200 250 300 350 400 450 500

(mV)

0

50 100 150 200 250 300 350 400 450 500

(mV)

0.5ms/DIV

V

SS

3467 G07

3467 G08

3467afd

4

LT3467/LT3467A

PIN FUNCTIONS ^(DFN/TSOT)

FB(Pin1/Pin3):FeedbackPin.Referencevoltageis1.255V.

V

(Pin 6/Pin 6): Input Supply Pin. Must be locally

IN

Connect resistive divider tap here. Minimize trace area at

bypassed.

FB. Set V

= 1.255V(1 + R1/R2).

OUT

SS(Pin7/Pin5):Soft-StartPin.Placeasoft-startcapacitor

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

to1.255V. Usealargercapacitorforslowerstart-up. Leave

ﬂoating if not in use.

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.

SHDN (Pin 8/Pin 4): Shutdown Pin. Tie to 2.4V or more

to enable device. Ground to shut down.

BLOCK DIAGRAM

250k

SS

SW

1.255V

REFERENCE

V

IN

+

–

COMPARATOR

–

A1

DRIVER

Q1

A2

R

Q

R

C

S

+

V

OUT

C

+

–

R1 (EXTERNAL)

0.01Ω

3

FB

R2 (EXTERNAL)

RAMP

GENERATOR

SHUTDOWN

SHDN

FB

GND

3467 F01

1.3MHz

OSCILLATOR*

*2.1MHz FOR LT3467A

Figure 1. Block Diagram

3467afd

5

LT3467/LT3467A

OPERATION

TheLT3467usesaconstantfrequency,current-modecon-

trol scheme to provide excellent line and load regulation.

Refer to the Block Diagram. At the start of each oscillator

cycle, the SR latch is set which turns on the power switch

Q1. A voltage proportional to the switch current is added

to a stabilizing ramp and the resulting sum is fed into the

positive terminal of the PWM comparator A2. When this

voltage exceeds the level at the negative input of A2, the

SR latch is reset, turning off the power switch. The level

at the negative input of A2 is set by the error ampliﬁer A1,

andissimplyanampliﬁedversionofthedifferencebetween

the feedback voltage and the reference voltage of 1.255V.

In this manner, the error ampliﬁer sets the correct peak

current level to keep the output in regulation. If the error

ampliﬁer’s output increases, more current is delivered to

the output. Similarly, if the error decreases, less current

is delivered. The soft-start feature of the LT3467 allows

for clean start-up conditions by limiting the rate of voltage

rise at the output of comparator A1 which, in turn, limits

the peak switch current. The soft-start pin is connected

to a reference voltage of 1.255V through a 250k resistor,

providing 4μA of current to charge the soft-start capacitor.

Typical values for the soft-start capacitor range from 10nF

to 200nF. The LT3467 has a current limit circuit not shown

in the Block Diagram. The switch current is constantly

monitoredandnotallowedtoexceedthemaximumswitch

current (typically 1.4A). If the switch current reaches

this value, the SR latch is reset regardless of the state

of comparator A2. This current limit protects the power

switch as well as the external components connected to

the LT3467.

TheBlockDiagramfortheLT3467A(notshown)isidentical

except that the oscillator frequency is 2.1MHz.

APPLICATIONS INFORMATION

Duty Cycle

Switching Frequency and Inductor Selection

The typical maximum duty cycle of the LT3467 is 94%

(88% for the LT3467A). The duty cycle for a given ap-

plication is given by:

TheLT3467switchesat1.3MHz, allowingforsmallvalued

inductors to be used. 4.7μH or 10μH will usually sufﬁce.

TheLT3467Aswitchesat2.1MHz,allowingforevensmaller

valued inductors to be used. 0.9μH to 6.8μH will usually

sufﬁce. Choose an inductor that can handle at least 1.2A

without saturating, and ensure that the inductor has a

| V_OUT| + | V_D| – | V |

| V_OUT| + | V_D| – | V_CESAT

IN

DC =

|

2

low DCR (copper-wire resistance) to minimize I R power

where V is the diode forward voltage drop and V

is

CESAT

D

losses.Notethatinsomeapplications,thecurrenthandling

requirements of the inductor can be lower, such as in the

SEPIC topology where each inductor only carries one-half

ofthetotalswitchcurrent.Forbetterefﬁciency,usesimilar

valuedinductorswithalargervolume.Manydifferentsizes

and shapes are available from various manufacturers.

Choose a core material that has low losses at 1.3MHz,

(2.1MHz for the LT3467A) such as ferrite core.

in the worst case 330mV (at 1.1A)

TheLT3467andLT3467Acanbeusedathigherdutycycles,

but must be operated in the discontinuous conduction

mode so that the actual duty cycle is reduced.

Setting Output Voltage

R1 and R2 determine the output voltage.

V

= 1.255V (1+ R1/R2)

OUT

3467afd

6

LT3467/LT3467A

APPLICATIONS INFORMATION

L1

2.7μH

D1

V

OUT

V

IN

5V

765mA AT V = 4.2V,

2.6V TO 4.2V

C1

IN

R1

402k

4.7μF

540mA AT V = 3.3V,

IN

V

IN

SW

360mA AT V = 2.6V

IN

C4

3.3pF

SHDN

OFF ON

LT3467

SS

FB

C2

R2

133k

C3

GND

15μF

0.047μF

C1, C2: X5R OR X7R, 6.3V

3467 TA05a

D1: ON SEMICONDUCTOR MBRM120

L1: SUMIDA CR43-2R7

Figure 2. Single Li-Ion Cell to 5V Boost Converter (Same as 1st Page Application)

Supply Current of Figure 2 During Start-Up

Table 1. Inductor Manufacturers

Without Soft-Start Capacitor

Sumida

TDK

(847) 956-0666

(847) 803-6100

(714) 852-2001

(408) 432-8331

www.sumida.com

www.tdk.com

Murata

FDK

www.murata.com

www.fdk.co.jp

V

OUT

1V/DIV

Soft-Start

The soft-start feature provides a way to limit the inrush

current drawn from the supply upon start-up. An internal

250k resistor charges the external soft-start capacitor

to 1.255V. After the capacitor reaches 0.15V the rate of

voltage rise at the output of the comparator A1 tracks the

rate of voltage rise of the soft-start capacitor. This limits

the inrush current drawn from the supply during start-

up. The soft-start feature plays another important role in

applications where the switch will reach levels of 30V or

higher. During start-up, excessively high switch current,

together with the presence of high voltage can overstress

the switch. A properly used soft-start feature will keep the

switchcurrentfromovershooting.Thispracticewillgreatly

improve the robustness of such designs. Once the part is

shut down, the soft-start capacitor is quickly discharged

to 0.4V, then slowly discharged through the 250k resistor

to ground. If the part is to be shut down and re-enabled in

a short period of time while soft-start is used, you must

ensure that the soft-start capacitor has enough time to

discharge before re-enabling the part. Typical values of

the soft-start capacitor range from 10nF to 200nF.

I

SUPPLY

0.5A/DIV

3467 AI01

0.1ms/DIV

Supply Current of Figure 2 During Start-Up

with a 47nF Soft-Start Capacitor

V

OUT

1V/DIV

I

SUPPLY

0.5A/DIV

3467 AI02

0.5ms/DIV

3467afd

7

LT3467/LT3467A

APPLICATIONS INFORMATION

Capacitor Selection

Aphaseleadzerocanbeintentionallyintroducedbyplacing

a capacitor (C4) in parallel with the resistor (R1) between

Low ESR (equivalent series resistance) capacitors should

beusedattheoutputtominimizetheoutputripplevoltage.

Multi-layer ceramic capacitors are an excellent choice,

as they have extremely low ESR and are available in very

small packages. X5R dielectrics are preferred, followed

by X7R, as these materials retain the capacitance over

wide voltage and temperature ranges. A 4.7μF to 15μF

output capacitor is sufﬁcient for most applications, but

systems with very low output currents may need only a

1μF or 2.2μF output capacitor. Solid tantalum or OS-CON

capacitors can be used, but they will occupy more board

area than a ceramic and will have a higher ESR. Always

use a capacitor with a sufﬁcient voltage rating.

V

and V as shown in Figure 2. The frequency of the

OUT

FB

zero is determined by the following equation.

1

ƒ_Z=

2π •R1•C4

By choosing the appropriate values for the resistor and

capacitor, the zero frequency can be designed to improve

the phase margin of the overall converter. The typical

target value for the zero frequency is between 35kHz

to 55kHz. Figure 3 shows the transient response of the

step-up converter from Figure 8 without the phase lead

capacitor C4. Although adequate for many applications,

phase margin is not ideal as evidenced by 2-3 “bumps”

in both the output voltage and inductor current. A 22pF

capacitor for C4 results in ideal phase margin, which is

revealed in Figure 4 as a more damped response and less

overshoot.

Ceramic capacitors also make a good choice for the input

decoupling capacitor, which should be placed as close as

possible to the LT3467. A 1μF to 4.7μF input capacitor

is sufﬁcient for most applications. Table 2 shows a list

of several ceramic capacitor manufacturers. Consult the

manufacturers for detailed information on their entire

selection of ceramic parts.

Diode Selection

A Schottky diode is recommendedforusewith the LT3467

and the LT3467A. The Philips PMEG 2005 is a very good

choice. Where the switch voltage exceeds 20V, use the

PMEG 3005 (a 30V diode). Where the switch voltage

exceeds 30V, use the PMEG 4005 (a 40V diode). These

diodes are rated to handle an average forward current of

0.5A. In applications where the average forward current

of the diode exceeds 0.5A, a Philips PMEG 2010 rated at

1A is recommended. For higher efﬁciency, use a diode

with better thermal characteristics such as the On Semi-

conductor MBRM120 (a 20V diode) or the MBRM140 (a

40V diode).

Table 2. Ceramic Capacitor Manufacturers

Taiyo Yuden

AVX

(408) 573-4150

(803) 448-9411

(714) 852-2001

www.t-yuden.com

www.avxcorp.com

www.murata.com

Murata

The decision to use either low ESR (ceramic) capacitors

or the higher ESR (tantalum or OS-CON) capacitors can

affect the stability of the overall system. The ESR of any

capacitor, along with the capacitance itself, contributes

a zero to the system. For the tantalum and OS-CON ca-

pacitors, this zero is located at a lower frequency due to

the higher value of the ESR, while the zero of a ceramic

capacitor is at a much higher frequency and can generally

be ignored.

3467afd

8

LT3467/LT3467A

APPLICATIONS INFORMATION

LOAD CURRENT

100mA/DIV

AC COUPLED

Layout Hints

ThehighspeedoperationoftheLT3467/LT3467Ademands

careful attention to board layout. You will not get adver-

tised performance with careless layout. Figure 5a shows

the recommended component placement for the ThinSOT

package. Figure 5b shows the recommended component

placement for the DFN package. Note the vias under the

Exposed Pad. These should connect to a local ground

plane for better thermal performance.

V

OUT

200mV/DIV

AC COUPLED

I

L1

5A/DIV

AC COUPLED

3467 F03

20μs/DIV

Figure 3. Transient Response of Figure 8’s Step-Up

Converter without Phase Lead Capacitor

L1

D1

C1

V

IN

V

OUT

LOAD CURRENT

C2

1

2

3

6

5

4

100mA/DIV

C

SS

AC COUPLED

SS

GND

SHDN

V

OUT

FB

200mV/DIV

R2

R1

AC COUPLED

I

L1

3467 F05a

5A/DIV

C3

V

OUT

AC COUPLED

3467 F04

20μs/DIV

Figure 5a. Suggested Layout—ThinSOT

Figure 4. Transient Response of Figure 8’s Step-Up

Converter with a 22pF Phase Lead Capacitor

V

OUT

C3

R1

Setting Output Voltage

R2

To set the output voltage, select the values of R1 and R2

(see Figure 2) according to the following equation.

SHDN

FB

1

2

3

4

8

7

6

5

GND

C

SS

V_OUT

⎛

⎞

R1= R2

– 1

C2

⎜

⎝

⎟

⎠

1.255V

V

OUT

V

IN

D1

A good value for R2 is 13.3k which sets the current in the

resistor divider chain to 1.255V/13.3k = 94μA.

C1

L1

3467 F05b

Figure 5b. Suggested Layout—DFN

3467afd

9

LT3467/LT3467A

APPLICATIONS INFORMATION

Compensation—Theory

From Figure 6, the DC gain, poles and zeroes can be

calculated as follows:

Like all other current mode switching regulators, the

LT3467/LT3467A needs to be compensated for stable

and efﬁcient operation. Two feedback loops are used in

the LT3467/LT3467A: a fast current loop which does not

require compensation, and a slower voltage loop which

does. Standard Bode plot analysis can be used to under-

stand and adjust the voltage feedback loop.

2

Output Pole: P1=

2 • π •R_L•C_OUT

1

Error Amp Pole: P2=

2 • π •R_O•C_C

1

Error Amp Zero: Z1=

2 • π •R_C•C_C

As with any feedback loop, identifying the gain and phase

contribution of the various elements in the loop is critical.

Figure 6 shows the key equivalent elements of a boost

converter. Because of the fast current control loop, the

power stage of the IC, inductor and diode have been re-

1.255

1

2

DC GAIN: A=

• V • g_ma•R_O• g_mp•R_L•

IN

2

V_OUT

1

ESR Zero: Z2 =

2 • π •R_ESR•C_OUT

placed by the equivalent transconductance ampliﬁer g_mp

.

g_mpacts as a current source where the output current is

proportional to the V_Cvoltage. Note that the maximum

output current of gmp is ﬁnite due to the current limit

in the IC.

V

²•R_L

IN

RHP Zero: Z3=

2 • π • V_OUT²•L

f_S

3

High Frequency Pole: P3>

–

1

Phase Lead Zero : Z4 =

g

mp

V

OUT

2 • π •R1•C_PL

+

C

PL

R

L

ESR

1

Phase LeadPole:P4 =

C

OUT

1.255V

REFERENCE

R1•R2

R1+R2

+

–

2 • π •C_PL

•

V

C

g

ma

R1

R2

R

C

R

O

The current mode zero is a right-half plane zero which can

be an issue in feedback control design, but is manageable

with proper external component selection.

C

3467 F06

C : COMPENSATION CAPACITOR

C

OUT

PL

ma

mp

C

g

: OUTPUT CAPACITOR

: PHASE LEAD CAPACITOR

: TRANSCONDUCTANCE AMPLIFIER INSIDE IC

: POWER STAGE TRANSCONDUCTANCE AMPLIFIER

R : COMPENSATION RESISTOR

C

R : OUTPUT RESISTANCE DEFINED AS V

DIVIDED BY I

LOAD(MAX)

L

OUT

R : OUTPUT RESISTANCE OF g

O

ma

R1, R2: FEEDBACK RESISTOR DIVIDER NETWORK

: OUTPUT CAPACITOR ESR

R

ESR

Figure 6. Boost Converter Equivalent Model

3467afd

10

LT3467/LT3467A

APPLICATIONS INFORMATION

Using the circuit of Figure 2 as an example, the following

table shows the parameters used to generate the Bode

plot shown in Figure 7.

Table 3. Bode Plot Parameters

PARAMETER

VALUE

10.4

15

UNITS

Ω

COMMENT

R

L

Application Speciﬁc

Not Adjustable

Adjustable

C

μF

OUT

50

40

0

R

10

mΩ

MΩ

pF

ESR

–45

R

0.4

60

30

–90

O

C

20

–135

–180

–225

–270

–315

–360

–405

–450

10

C

3.3

100

402

133

5

pF

PL

0

R

kΩ

V

Not Adjustable

Adjustable

C

–10

–20

–30

–40

–50

R1

R2

Adjustable

V

Application Speciﬁc

Not Adjustable

Application Speciﬁc

Not Adjustable

OUT

GAIN

PHASE

V

3.3

35

V

IN

100

1k

10k

100k

1M

g

μmho

mho

μH

ma

FREQUENCY (Hz)

7.5

2.7

1.3*

mp

3467 F07

L

Figure 7. Bode Plot of 3.3V to 5V Application

f

MHz

S

*2.1MHz for LT3467A

From Figure 7, the phase is –138° when the gain reaches

0dB giving a phase margin of 42°. This is more than

adequate. The crossover frequency is 37kHz.

TYPICAL APPLICATIONS

Lithium-Ion to 6V Step-Up DC/DC Converter

Li-Ion to 6V

95

L1

D1

2.2μH

V

IN

90

85

80

75

70

65

60

55

50

V

= 4.2V

OUT

6V

IN

2.7V TO 4.2V

R1

275mA AT V = 2.7V

V

IN

= 3.8V

IN

501k

V

SW

490mA AT V = 3.8V

IN

V

IN

= 2.7V

590mA AT V = 4.2V

IN

C1

C3

1.8pF

SHDN

LT3467

2.2μF

SS

FB

C2

15μF

C4

0.047μF

R2

133k

GND

C1, C2: X5R OR X7R, 6.3V

3467 TA02

D1: ON SEMICONDUCTOR MBRM120

L1: SUMIDA CR43-2R2

50 100

300 400 500 600 700

(mA)

200

I

OUT

3467 TA02b

3467afd

11

LT3467/LT3467A

TYPICAL APPLICATIONS

4-Cell to 5V SEPIC Converter

C3

1μF

L1

10μH

D1

4V TO 6.5V

V

OUT

5V

C1

325mA AT V = 4V

IN

2.2μF

400mA AT V = 5V

IN

450mA AT V = 6.5V

V

SW

IN

C5

4.7pF

IN

SHDN

255k

4-CELL

BATTERY

LT3467

L2

10μH

C2

10μF

SS

FB

C4

0.047μF

GND

84.5k

D1: PHILIPS PMEG 2010

L1, L2: MURATA LQH32CN100K33L

C1, C3: X5R or X7R, 10V

C2: X5R or X7R, 6.3V

3467 TA03

5V to 40V Boost Converter

L1

2.7μH

D1

V

OUT

V

IN

40V

20mA

5V

C1

4.7μF

V

SW

IN

R1

412k

SHDN

LT3467

SS

C2

1μF

FB

C3

0.1μF

R2

13.3k

GND

C1: X5R or X7R, 6.3V

C2: X5R or X7R, 50V

3467 TA04a

D1: ON SEMICONDUCTOR, MBRM140

L1: SUMIDA CD43-2R7

15V Dual Output Converter with Output Disconnect

C4

1μF

L1

10μH

D1

V

15V

IN

5V

100mA

C1

R3

1Ω

R1

147k

2.2μF

C5

1μF

V

SW

IN

OFF ON

SHDN

D2

C2

2.2μF

LT3467

SS

FB

C6

0.047μF

R2

13.3k

GND

C3

2.2μF

C1: X5R or X7R, 6.3V

R4

1Ω

D3

D4

C2 TO C5: X5R or X7R, 16V

D1 TO D4: PHILIPS PMEG 2005

L1: SUMIDA CR43-100

–15V

100mA

3467 TA05

3467afd

12

LT3467/LT3467A

TYPICAL APPLICATIONS

9V, 18V, –9V Triple Output TFT-LCD Bias Supply with Soft-Start

D1

D2

18V

10mA

C4

1μF

C3

0.1μF

Start-Up Waveforms

L1

4.7μH

D5

V

9V

220mA

IN

9V OUTPUT

5V/DIV

3.3V

C1

2.2μF

–9V OUTPUT

5V/DIV

V

SW

IN

R1

124k

V

SHDN

LT3467

C5

10μF

SS

FB

3.3V

GND

R2

20k

0V

18V OUTPUT

10V/DIV

C2

0.1μF

C7

0.1μF

C1: X5R OR X7R, 6.3V

C2,C3, C5, C6: X5R OR X7R, 10V

C4: X5R OR X7R, 25V

D1 TO D4: PHILIPS BAT54S OR EQUIVALENT

D5: PHILIPS PMEG 2005

L1: PANASONIC ELT5KT4R7M

I

L1

D4

D3

0.5A/DIV

3467 TA06b

2ms/DIV

C6

1μF

–9V

10mA

3467 TA06a

8V, 23V, –8V Triple Output TFT-LCD Bias Supply with Soft-Start

D1

D2

D3

D4

23V

10mA

C3

0.1μF

C4

0.1μF

C5

0.1μF

C6

1μF

Start-Up Waveforms

L1

4.7μH

D7

V

8V OUTPUT

5V/DIV

–8V OUTPUT

5V/DIV

8V

IN

3.3V

SHDN

3.3V

270mA

C1

R1

V

SW

2.2μF

IN

113k

V

SHDN

LT3467

C7

10μF

SS

FB

GND

R2

21k

23V OUTPUT

10V/DIV

0V

C9

C2

0.1μF

C1: X5R OR X7R, 6.3V

I

L1

0.5A/DIV

D5

D6

C2 TO C4, C7, C8: X5R OR X7R, 10V

C5: X5R OR X7R, 16V

3467 TA07b

2ms/DIV

C8

C6: X5R OR X7R, 25V

1μF

D1 TO D6: PHILIPS BAT54S OR EQUIVALENT

D7: PHILIPS PMEG 2005

–8V

10mA

L1: PANASONIC ELT5KT4R7M

3467 TA07a

3467afd

13

LT3467/LT3467A

TYPICAL APPLICATIONS

Single Li-Ion Cell to 5V Boost Converter

Efﬁciency

L1

95

90

85

80

75

70

65

60

55

50

D1

0.9μH

V

IN

OUT

5V

2.6V TO 4.2V

R1

600mA AT V = 4.2V

IN

8.06k

V

SW

360mA AT V = 3.3V

IN

C1

4.7μF

V

IN

= 4.2V

IN

250mA AT V = 2.6V

IN

V

IN

= 3.3V

C4*

75pF

SHDN

OFF ON

C3

V

IN

= 2.6V

LT3467A

SS

FB

C2*

22μF

R2

GND

0.047μF

2.67k

C1, C2: X5R OR X7R, 6.3V

D1: PHILIPS PMEG 2010

L1: FDK MIPW3226D0R9M

*C2 CAN BE 10μF IN A 1210 OR LARGER PACKAGE WITH

THE ADDITION OF C4, OTHERWISE C4 IS OPTIONAL

3467 TA09a

50 100 150 200 250 300 350 400 450 500

(mA)

I

OUT

3467 TA09b

2.6V-3.3V to 5V Boost Converter

Efﬁciency

90

85

80

75

70

65

60

55

50

L1

D1

1.5μH

V

IN

OUT

5V

2.6V TO 3.3V

R1

430mA AT V = 3.3V

270mA AT V = 2.6V

IN

V

= 3.3V

IN

8.06k

V

SW

C1

IN

V

= 2.6V

IN

4.7μF

C4

56pF

SHDN

LT3467A

OFF ON

C3

SS

FB

C2

10μF

GND

R2

0.047μF

2.67k

C1, C2: X5R OR X7R, 6.3V

D1: PHILIPS PMEG 2010

L1: FDK MIP3226D1R5M

3467 TA08a

50 100 150 200 250 300 350 400 450 500

(mA)

I

OUT

3467 TA08b

3.3V to 15V, 135mA Step-Up Converter

Efﬁciency

90

80

70

60

50

40

30

L1

D1

6.8μH

V

OUT

V

IN

15V

135mA

3.3V

R1

16.5k

V

SW

C1

4.7μF

IN

C4

68pF

SHDN

LT3467A

OFF ON

C3

SS

FB

C2

2.2μF

R2

GND

1.5k

0.047μF

C1: X5R OR X7R, 6.3V

C2: X5R OR X7R, 16V

D1: PHILIPS PMEG 2010

3467 TA10a

L1: SUMIDA CMD4D13-6R8MC

140

20

40

60

80 100 120

160

I

(mA)

OUT

3467 TA10b

3467afd

14

LT3467/LT3467A

PACKAGE DESCRIPTION

DDB Package

8-Lead Plastic DFN (3mm × 2mm)

(Reference LTC DWG # 05-08-1702 Rev B)

0.61 p0.05

(2 SIDES)

R = 0.115

0.40 p 0.10

3.00 p0.10

(2 SIDES)

TYP

R = 0.05

TYP

5

8

0.70 p0.05

2.55 p0.05

1.15 p0.05

2.00 p0.10

PIN 1 BAR

(2 SIDES)

TOP MARK

PIN 1

R = 0.20 OR

0.25 s 45o

(SEE NOTE 6)

PACKAGE

OUTLINE

0.56 p 0.05

(2 SIDES)

CHAMFER

4

1

(DDB8) DFN 0905 REV B

0.25 p 0.05

0.75 p0.05

0.200 REF

0.50 BSC

2.20 p0.05

(2 SIDES)

0.50 BSC

2.15 p0.05

(2 SIDES)

0 – 0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

BOTTOM VIEW—EXPOSED PAD

NOTE:

1. DRAWING CONFORMS TO VERSION (WECD-1) IN JEDEC PACKAGE OUTLINE M0-229

2. DRAWING NOT TO SCALE

3. ALL DIMENSIONS ARE IN MILLIMETERS

4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE

MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE

5. EXPOSED PAD SHALL BE SOLDER PLATED

6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE

S6 Package

6-Lead Plastic TSOT-23

(Reference LTC DWG # 05-08-1636)

2.90 BSC

(NOTE 4)

0.62

MAX

0.95

REF

1.22 REF

1.4 MIN

1.50 – 1.75

2.80 BSC

3.85 MAX 2.62 REF

(NOTE 4)

PIN ONE ID

RECOMMENDED SOLDER PAD LAYOUT

PER IPC CALCULATOR

0.30 – 0.45

6 PLCS (NOTE 3)

0.95 BSC

0.80 – 0.90

0.20 BSC

DATUM ‘A’

0.01 – 0.10

1.00 MAX

0.30 – 0.50 REF

1.90 BSC

0.09 – 0.20

(NOTE 3)

S6 TSOT-23 1005

NOTE:

1. DIMENSIONS ARE IN MILLIMETERS

2. DRAWING NOT TO SCALE

3. DIMENSIONS ARE INCLUSIVE OF PLATING

4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR

5. MOLD FLASH SHALL NOT EXCEED 0.254mm

6. JEDEC PACKAGE REFERENCE IS MO-193

3467afd

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

15

LT3467/LT3467A

TYPICAL APPLICATIONS

L1

Efﬁciency

D1

4.7μH

V

OUT

V

90

85

80

75

70

65

60

55

50

IN

12V

5V

C1

2.2μF

270mA

R1

115k

V

SW

IN

C4*

22pF

SHDN

C2

10μF

LT3467

SS

FB

C3

0.047μF

R2

13.3k

GND

C1: X5R OR X7R, 6.3V

C2: X5R OR X7R, 16V

D1: PHILIPS PMEG 2010

L1: SUMIDA CR43-4R7

*OPTIONAL

3467 F08a

300

50

100

150

200

(mA)

250

350

Figure 8. 5V to 12V, 270mA Step-Up Converter

I

OUT

3467 F08b

Efﬁciency

L1

D1

3.3μH

V

OUT

V

IN

5V

95

90

85

80

75

70

65

60

55

50

12V

260mA

R1

115k

V

SW

C1

4.7μF

IN

C4

12pF

SHDN

OFF ON

C3

LT3467A

GND

SS

FB

C2

10μF

R2

0.047μF

13.3k

C1: X5R OR X7R, 6.3V

C2: X5R OR X7R, 16V

3467 F09a

D1: PHILIPS PMEG 2010

L1: SUMIDA CDRH4D18-3R3

Figure 9. 5V to 12V, 260mA Step-Up Converter

50

100

150

200

250

300

I

(mA)

OUT

3467 F09b

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

V : 1V to 15V, V

LT1615/LT1615-1 300mA/80mA (I ), High Efﬁciency Step-Up DC/DC Converter

= 34V, I = 20μA, I < 1μA,

SW

IN

OUT(MAX)

Q

SD

ThinSOT Package

LT1618

1.5A (I ), 1.25MHz, High Efﬁciency Step-Up DC/DC Converter

90% Efﬁciency, V : 1.6V to 18V, V

= 35V, I = 1.8mA,

SW

IN

OUT(MAX) Q

I

< 1μA, MS Package

SD

Q

LTC1700

No R

™, 530kHz, Synchronous Step-Up DC/DC Controller

SENSE

95% Efﬁciency, V : 0.9V to 5V, I = 200μA, I < 10μA,

IN SD

MS Package

LTC1871

Wide Input Range, 1MHz, No R

Flyback and SEPIC Controller

Current Mode Boost,

92% Efﬁciency, V : 2.5V to 36V, I = 250μA, I < 10μA,

SENSE

IN

Q

SD

MS Package

High Efﬁciency, V : 2.6V to 16V, V

LT1930/LT1930A

LT1946/LT1946A

LT1961

1A (I ), 1.2MHz/2.2MHz, High Efﬁciency Step-Up

= 34V,

SW

IN

OUT(MAX)

DC/DC Converter

I = 4.2mA/5.5mA, I < 1μA, ThinSOT Package

Q SD

1.5A (I ), 1.2MHz/2.7MHz, High Efﬁciency Step-Up

High Efﬁciency, V : 2.45V to 16V, V

SD

= 34V, I = 3.2mA,

OUT(MAX) Q

SW

IN

DC/DC Converter with Soft-Start

I

< 1μA, MS8 Package

1.5A (I ), 1.25MHz, High Efﬁciency Step-Up DC/DC Converter

90% Efﬁciency, V : 3V to 25V, V

SD

= 35V, I = 0.9mA,

OUT(MAX) Q

SW

IN

I

< 6μA, MS8E Package

LTC3400/

LTC3400B

600mA (I ), 1.2MHz, Synchronous Step-Up DC/DC Converter

92% Efﬁciency, V : 0.85V to 5V, V

= 5V,

SW

IN

OUT(MAX)

I = 19μA/300μA, I < 1μA, ThinSOT Package

Q

SD

LTC3401

LTC3402

LT3464

1A (I ), 3MHz, Synchronous Step-Up DC/DC Converter

97% Efﬁciency, V : 0.5V to 5V, V

SD

= 5.5V, I = 38μA,

Q

SW

IN

OUT(MAX)

I

< 1μA, MS Package

2A (I ), 3MHz, Synchronous Step-Up DC/DC Converter

97% Efﬁciency, V : 0.5V to 5V, V

SD

= 5.5V, I = 38μA,

Q

SW

IN

OUT(MAX)

I

< 1μA, MS Package

85mA (I ), High Efﬁciency Step-Up DC/DC Converter with

V : 2.3V to 10V, V

= 34V, I = 25μA, I < 1μA,

OUT(MAX) Q SD

SW

IN

Integrated Schottky and PNP Disconnect

ThinSOT Package

No R

is a trademark of Linear Technology Corporation.

SENSE

3467afd

LT 1208 REV D • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

16

●

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LT3467EDDB#TRM
厂家：	Linear
描述：	LT3467 - 1.1A Step-Up DC/DC Converter with Integrated Soft-Start; Package: DFN; Pins: 8; Temperature Range: -40°C to 85°C 转换器软启动
文件：	总16页 (文件大小：262K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LT3467EDDB#TRM [Linear]

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