LT1308BCS8#PBF_技术文档

LT1308A/LT1308B

High Current, Micropower

Single Cell, 600kHz

DC/DC Converters

DESCRIPTION

The LT^®1308A/LT1308B are micropower, ﬁxed frequency

step-up DC/DC converters that operate over a 1V to 10V

input voltage range. They are improved versions of the

LT1308 and are recommended for use in new designs.

The LT1308A features automatic shifting to power sav-

ing Burst Mode operation at light loads and consumes

just 140μA at no load. The LT1308B features continuous

switching at light loads and operates at a quiescent cur-

rent of 2.5mA. Both devices consume less than 1μA in

shutdown.

FEATURES

n

5V at 1A from a Single Li-Ion Cell

n

5V at 800mA in SEPIC Mode from Four NiCd Cells

n

Fixed Frequency Operation: 600kHz

n

Boost Converter Outputs up to 34V

n

Starts into Heavy Loads

n

Automatic Burst Mode™ Operation at

Light Load (LT1308A)

Continuous Switching at Light Loads (LT1308B)

n

Low V

Switch: 300mV at 2A

CESAT

n

Pin-for-Pin Upgrade Compatible with LT1308

Lower Quiescent Current in Shutdown: 1μA (Max)

Improved Accuracy Low-Battery Detector

Reference: 200mV 2%

Low-battery detector accuracy is signiﬁcantly tighter than

the LT1308. The 200mV reference is speciﬁed at 2%

at room and 3% over temperature. The shutdown pin

enables the device when it is tied to a 1V or higher source

n

Available in 8-Lead SO and 14-Lead TSSOP Packages

and does not need to be tied to V as on the LT1308. An

IN

internal V clamp results in improved transient response

C

APPLICATIONS

and the switch voltage rating has been increased to 36V,

n

GSM/CDMA Phones

Digital Cameras

LCD Bias Supplies

Answer-Back Pagers

GPS Receivers

Battery Backup Supplies

Handheld Computers

enabling higher output voltage applications.

n

The LT1308A/LT1308B are available in the 8-lead SO and

the 14-lead TSSOP packages.

L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective

owners.

n

TYPICAL APPLICATION

Converter Efﬁciency

L1

95

D1

4.7μH

V

IN

= 3.6V

V

IN

= 4.2V

= 2.5V

5V

1A

90

85

80

75

70

65

60

55

50

V

SW

IN

+

C1

47μF

R1*

LBO

LBI

V

IN

309k

LT1308B

V

IN

= 1.5V

+

Li-Ion

CELL

C2

220μF

SHUTDOWN

SHDN

FB

GND

V

C

R2

100k

47k

100pF

C1: AVX TAJC476M010

C2: AVX TPSD227M006

D1: IR 10BQ015

L1: MURATA LQH6C4R7

*R1: 887k FOR V = 12V

OUT

1

10

100

1000

1308A/B F01a

LOAD CURRENT (mA)

Figure 1. LT1308B Single Li-Ion Cell to 5V/1A DC/DC Converter

1308A/B F01b

1308abfb

1

LT1308A/LT1308B

(Note 1)

ABSOLUTE MAXIMUM RATINGS

V , SHDN, LBO Voltage........................................... 10V

Operating Temperature Range

IN

SW Voltage .............................................. –0.4V to 36V

Commercial............................................. 0°C to 70°C

Extended Commerial (Note 2) ............ –40°C to 85°C

Industrial ........................................... –40°C to 85°C

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

Lead Temperature (Soldering, 10 sec) ................. 300°C

FB Voltage......................................................... V + 1V

IN

V Voltage ................................................................. 2V

C

LBI Voltage ................................................. –0.1V to 1V

Current into FB Pin............................................... 1mA

PIN CONFIGURATION

TOP VIEW

LBO

LBI

V

1

2

3

4

5

6

7

14

13

12

11

10

9

C

FB

SHDN

GND

TOP VIEW

V

IN

V

1

2

3

4

8

7

6

5

LBO

LBI

C

V

IN

FB

SHDN

GND

SW

GND

V

IN

GND

SW

GND

8

S8 PACKAGE

8-LEAD PLASTIC SO

F PACKAGE

14-LEAD PLASTIC TSSOP

(NOTE 6)

T

= 125°C, θ = 190°C/W

JA

JMAX

T

JMAX

= 125°C, θ = 80°C/W

JA

OBSOLETE, FOR INFORMATION PURPOSES ONLY

Contact Linear Technology for Potential Replacement

ORDER INFORMATION

LEAD FREE FINISH

LT1308ACS8#PBF

LT1308AIS8#PBF

LT1308BCS8#PBF

LT1308BIS8#PBF

LT1308ACF#PBF

LT1308BCF#PBF

LEAD BASED FINISH

LT1308ACS8

TAPE AND REEL

LT1308ACS8#TRPBF

LT1308AIS8#TRPBF

LT1308BCS8#TRPBF

LT1308BIS8#TRPBF

LT1308ACF#TRPBF

LT1308BCF#TRPBF

TAPE AND REEL

LT1308ACS8#TR

LT1308AIS8#TR

PART MARKING

1308A

PACKAGE DESCRIPTION

8-Lead Plastic SO

TEMPERATURE RANGE

0°C to 70°C

1308AI

8-Lead Plastic SO

–40°C to 85°C

0°C to 70°C

1308B

8-Lead Plastic SO

1308BI

8-Lead Plastic SO

–40°C to 85°C

0°C to 70°C

LT1308ACF

LT1308BCF

PART MARKING

1308A

14-Lead Plastic TSSOP

PACKAGE DESCRIPTION

8-Lead Plastic SO

0°C to 70°C

TEMPERATURE RANGE

0°C to 70°C

LT1308AIS8

1308AI

8-Lead Plastic SO

–40°C to 85°C

0°C to 70°C

LT1308BCS8

LT1308BCS8#TR

LT1308BIS8#TR

1308B

8-Lead Plastic SO

LT1308BIS8

1308BI

8-Lead Plastic SO

–40°C to 85°C

0°C to 70°C

LT1308ACF

LT1308ACF#TR

LT1308ACF

LT1308BCF

14-Lead Plastic TSSOP

LT1308BCF

LT1308BCF#TR

0°C to 70°C

Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges.

For more information on lead free part marking, go to: http://www.linear.com/leadfree/

This product is only offered in trays. For more information go to: http://www.linear.com/packaging/

1308abfb

2

LT1308A/LT1308B

ELECTRICAL CHARACTERISTICS ^Thel denotes the speciﬁcations which apply over the full operating temperature

range, otherwise speciﬁcations are at T_A= 25°C. Commercial Grade 0°C to 70°C. V_IN= 1.1V, V_SHDN= V_IN, unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

I

Q

Quiescent Current

Not Switching, LT1308A

Switching, LT1308B

SHDN

140

2.5

0.01

240

4

1

μA

mA

μA

V

= 0V (LT1308A/LT1308B)

l

V

Feedback Voltage

1.20

1.22

27

1.24

80

V

FB

I

B

FB Pin Bias Current

Reference Line Regulation

(Note 3)

nA

1.1V ≤ V ≤ 2V

0.03

0.01

0.4

0.2

%/V

IN

2V ≤ V ≤ 10V

IN

Minimum Input Voltage

Error Amp Transconductance

Error Amp Voltage Gain

Switching Frequency

0.92

60

1

V

μmhos

V/V

g

∆I = 5μA

m

A

100

600

90

V

l

f

V

IN

= 1.2V

500

82

2

700

4.5

kHz

OSC

Maximum Duty Cycle

Switch Current Limit

%

Duty Cycle = 30% (Note 4)

3

A

Switch V

I

SW

I

SW

= 2A (25°C, 0°C), V = 1.5V

290

330

350

400

mV

CESAT

IN

= 2A (70°C), V = 1.5V

IN

Burst Mode Operation Switch Current Limit

(LT1308A)

V

IN

= 2.5V, Circuit of Figure 1

400

mA

l

Shutdown Pin Current

V

SHDN

V

SHDN

V

SHDN

= 1.1V

= 6V

= 0V

2

5

35

0.1

μA

20

0.01

LBI Threshold Voltage

196

194

200

204

206

mV

l

LBO Output Low

I

= 50μA

0.1

0.01

33

0.25

0.1

V

μA

SINK

LBO Leakage Current

V

= 250mV, V

= 5V

LBO

LBI

LBI Input Bias Current (Note 5)

Low-Battery Detector Gain

Switch Leakage Current

= 150mV

100

nA

3000

0.01

V/V

μA

l

V

= 5V

10

SW

The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at T_A= 25°C.

Industrial Grade –40°C to 85°C. V_IN= 1.2V, V_SHDN= V_IN, unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

l

I

Q

Quiescent Current

Not Switching, LT1308A

Switching, LT1308B

SHDN

140

2.5

0.01

240

4

1

μA

mA

μA

V

= 0V (LT1308A/LT1308B)

l

V

Feedback Voltage

1.19

1.22

27

1.25

80

V

FB

I

FB Pin Bias Current

Reference Line Regulation

(Note 3)

nA

B

l

1.1V ≤ V ≤ 2V

0.05

0.01

0.4

0.2

%/V

IN

2V ≤ V ≤ 10V

IN

Minimum Input Voltage

Error Amp Transconductance

Error Amp Voltage Gain

0.92

60

1

V

μmhos

V/V

g

∆I = 5μA

m

A

100

V

1308abfb

3

LT1308A/LT1308B

The l denotes the speciﬁcations which apply over the full operating temperature

ELECTRICAL CHARACTERISTICS

range, otherwise speciﬁcations are at T_A= 25°C. Industrial Grade –40°C to 85°C. V_IN= 1.2V, V_SHDN= V_IN, unless otherwise noted.

SYMBOL

PARAMETER

CONDITIONS

MIN

500

82

TYP

600

90

MAX

UNITS

kHz

%

l

f

Switching Frequency

Maximum Duty Cycle

Switch Current Limit

750

OSC

Duty Cycle = 30% (Note 4)

2

3

4.5

A

Switch V

I

= 2A (25°C, –40°C), V = 1.5V

290

330

350

400

mV

CESAT

SW

IN

= 2A (85°C), V = 1.5V

IN

Burst Mode Operation Switch Current Limit

(LT1308A)

V

= 2.5V, Circuit of Figure 1

400

mA

IN

l

Shutdown Pin Current

V

SHDN

V

SHDN

V

SHDN

= 1.1V

= 6V

= 0V

2

5

35

0.1

μA

20

0.01

LBI Threshold Voltage

196

193

200

204

207

mV

l

LBO Output Low

I

= 50μA

0.1

0.01

33

0.25

0.1

V

μA

SINK

LBO Leakage Current

V

= 250mV, V

= 5V

LBO

LBI

LBI Input Bias Current (Note 5)

Low-Battery Detector Gain

Switch Leakage Current

= 150mV

100

nA

LBI

3000

0.01

V/V

μA

l

V

= 5V

10

SW

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 LT1308ACS8, LT1308ACF, LT1308BCS8 and LT1308BCF are

designed, characterized and expected to meet the industrial temperature

limits, but are not tested at –40°C and 85°C. I grade devices are

guaranteed over the –40°C to 85°C operating temperature range.

Note 4: Switch current limit guaranteed by design and/or correlation to

static tests. Duty cycle affects current limit due to ramp generator (see

Block Diagram).

Note 5: Bias current ﬂows out of LBI pin.

Note 6: Connect the four GND pins (Pins 4–7) together at the device.

Similarly, connect the three SW pins (Pins 8–10) together and the two V

pins (Pins 11, 12) together at the device.

IN

Note 3: Bias current ﬂows into FB pin.

TYPICAL PERFORMANCE CHARACTERISTICS

LT1308B

3.3V Output Efﬁciency

LT1308A

3.3V Output Efﬁciency

LT1308A

5V Output Efﬁciency

95

90

85

80

75

70

65

60

55

50

95

90

85

80

75

70

65

60

55

50

95

90

85

80

75

70

65

60

55

50

V

= 4.2V

= 2.5V

IN

V

= 2.5V

IN

V = 3.6V

IN

V

= 1.8V

V

= 2.5V

IN

V

IN

= 1.8V

V

IN

= 1.2V

V

IN

= 1.5V

V

= 1.2V

V

IN

1

10

100

1000

1

10

100

1000

1

10

100

1000

LOAD CURRENT (mA)

1308A/B G02

1308A/B G01

1308A/B G03

1308abfb

4

LT1308A/LT1308B

TYPICAL PERFORMANCE CHARACTERISTICS

LT1308B

Switch Current Limit vs

Duty Cycle

Switch Saturation Voltage

12V Output Efﬁciency

vs Current

4.0

3.5

3.0

2.5

2.0

500

90

85

80

75

70

65

60

55

50

V

IN

= 5V

400

V

IN

= 3.3V

85°C

300

25°C

200

–40°C

100

0

0.5

1.0

1.5

0

2.0

0

20

40

60

80

100

1

10

100

1000

LOAD CURRENT (mA)

SWITCH CURRENT (A)

DUTY CYCLE (%)

1308A/B G04

1308 G06

1308 • G05

FB, LBI Bias Current vs

Temperature

Low Battery Detector Reference

vs Temperature

SHDN Pin Bias Current vs Voltage

50

40

30

20

10

0

80

70

60

50

40

30

20

10

0

203

202

201

200

199

198

197

196

195

–40°C

LBI

25°C

85°C

FB

75

0

2

4

6

8

10

–50

–25

0

25

50

100

75

–50

–25

0

25

50

100

TEMPERATURE (°C)

SHDN PIN VOLTAGE (V)

1308 G07

1308 • G08

1308 • G09

Oscillator Frequency vs

Temperature

LT1308A Quiescent Current vs

Temperature

Feedback Pin Voltage vs

Temperature

180

170

160

150

140

130

120

110

100

1.25

1.24

1.23

1.22

1.21

1.20

1.19

1.18

800

750

700

650

600

550

500

450

400

75

–50

–25

0

25

50

100

75

–50

–25

0

25

50

100

–50

–2.5

0

25

50

100

TEMPERATURE (°C)

1308 • G11

1308 • G12

1308 • G10

1308abfb

5

LT1308A/LT1308B

PIN FUNCTIONS ^(SO/TSSOP)

V (Pin 1/Pin 1): Compensation Pin for Error Ampliﬁer.

SW (Pin 5/Pins 8, 9, 10): Switch Pins. Connect induc-

tor/diode here. Minimize trace area at these pins to keep

EMI down. For the TSSOP package, connect all SW pins

together at the package.

C

ConnectaseriesRCfromthispintoground.Typicalvalues

are 47kΩ and 100pF. Minimize trace area at V .

C

FB (Pin 2/Pin 2): Feedback Pin. Reference voltage is

1.22V. Connect resistive divider tap here. Minimize trace

V (Pin 6/Pins 11, 12): Supply Pins. Must have local

IN

area at FB. Set V

according to:

bypass capacitor right at the pins, connected directly to

OUT

ground. For the TSSOP package, connect both V pins

IN

V

= 1.22V(1 + R1/R2).

OUT

together at the package.

SHDN (Pin 3/Pin 3): Shutdown. Ground this pin to turn

off switcher. To enable, tie to 1V or more. SHDN does

LBI (Pin 7/Pin 13): Low-Battery Detector Input. 200mV

reference. Voltage on LBI must stay between –100mV

and 1V. Low-battery detector does not function with

SHDN pin grounded. Float LBI pin if not used.

not need to be at V to enable the device.

IN

GND (Pin 4/Pins 4, 5, 6, 7): Ground. Connect directly

to local ground plane. Ground plane should enclose all

components associated with the LT1308. PCB copper

connected to these pins also functions as a heat sink. For

the TSSOP package, connect all pins to ground copper

to get the best heat transfer. This keeps chip heating to

a minimum.

LBO (Pin 8/Pin 14): Low-Battery Detector Output. Open

collector,cansink50μA.A220kΩpull-upisrecommend-

ed. LBO is high impedance when SHDN is grounded.

1308abfb

6

LT1308A/LT1308B

BLOCK DIAGRAMS

V

IN

V

IN

Q4

2V

BE

6

V

IN

R5

40k

R6

40k

SHDN

SHUTDOWN

3

+

V

C

g

1

m

V

OUT

LBI

7

–

+

–

+

–

R1

LBO

8

ERROR

AMPLIFIER

(EXTERNAL)

*

FB

2

ENABLE

200mV

Q1

Q2

FB

×10

BIAS

A4

A1

COMPARATOR

R2

R3

30k

(EXTERNAL)

SW

5

–

+

DRIVER

R4

140k

FF

RAMP

GENERATOR

Q3

R

Q

+

Σ

S

A2

+

A = 3

–

0.03Ω

600kHz

OSCILLATOR

4

*HYSTERESIS IN LT1308A ONLY

1308 BD2a

GND

Figure 2a. LT1308A/LT1308B Block Diagram (SO-8 Package)

V

IN

Q4

2V

BE

V

11

12

IN

V

IN

R5

40k

R6

40k

SHDN

IN

SHUTDOWN

3

+

V

C

g

1

m

V

OUT

LBI

13

–

+

–

+

–

R1

LBO

14

ERROR

AMPLIFIER

(EXTERNAL)

*

FB

2

ENABLE

200mV

Q1

Q2

FB

×10

BIAS

A4

A1

COMPARATOR

R2

SW SW SW

8 10

R3

30k

(EXTERNAL)

9

–

+

DRIVER

R4

140k

FF

RAMP

GENERATOR

Q3

R

Q

+

Σ

S

A2

+

A = 3

–

0.03ꢀ

5

600kHz

OSCILLATOR

4

6

7

*HYSTERESIS IN LT1308A ONLY

1308 BD2b

GND GND GND GND

Figure 2b. LT1308A/LT1308B Block Diagram (TSSOP Package)

1308abfb

7

LT1308A/LT1308B

APPLICATIONS INFORMATION

OPERATION

Low-battery detector A4’s open-collector output (LBO)

pulls low when the LBI pin voltage drops below 200mV.

There is no hysteresis in A4, allowing it to be used as an

ampliﬁerinsomeapplications.Theentiredeviceisdisabled

whentheSHDNpinisbroughtlow.Toenabletheconverter,

The LT1308A combines a current mode, ﬁxed frequency

PWM architecture with Burst Mode micropower opera-

tion to maintain high efﬁciency at light loads. Operation

can be best understood by referring to the block diagram

in Figure 2. Q1 and Q2 form a bandgap reference core

whose loop is closed around the output of the converter.

SHDN must be at 1V or greater. It need not be tied to V

IN

as on the LT1308.

When V is 1V, the feedback voltage of 1.22V, along with

The LT1308B differs from the LT1308A in that there is no

hysteresis in comparator A1. Also, the bias point on A1 is

set lower than on the LT1308B so that switching can occur

at inductor current less than 100mA. Because A1 has no

hysteresis, there is no Burst Mode operation at light loads

and the device continues switching at constant frequency.

Thisresultsintheabsenceoflowfrequencyoutputvoltage

ripple at the expense of efﬁciency.

IN

an 80mV drop across R5 and R6, forward biases Q1 and

Q2’sbasecollectorjunctionsto300mV. Becausethisisnot

enough to saturate either transistor, FB can be at a higher

voltage than V . When there is no load, FB rises slightly

IN

above 1.22V, causing V (the error ampliﬁer’s output) to

C

decrease. When V reaches the bias voltage on hyster-

C

etic comparator A1, A1’s output goes low, turning off

all circuitry except the input stage, error ampliﬁer and

low-battery detector. Total current consumption in this

state is 140μA. As output loading causes the FB voltage to

decrease,A1’soutputgoeshigh,enablingtherestoftheIC.

Switch current is limited to approximately 400mA initially

after A1’s output goes high. If the load is light, the output

voltage(andFBvoltage)willincreaseuntilA1’soutputgoes

low, turning off the rest of the LT1308A. Low frequency

ripple voltage appears at the output. The ripple frequency

is dependent on load current and output capacitance.

This Burst Mode operation keeps the output regulated

and reduces average current into the IC, resulting in high

efﬁciency even at load currents of 1mA or less.

The difference between the two devices is clearly illus-

trated in Figure 3. The top two traces in Figure 3 shows an

LT1308A/LT1308Bcircuit,usingthecomponentsindicated

in Figure 1, set to a 5V output. Input voltage is 3V. Load

current is stepped from 50mA to 800mA for both circuits.

Low frequency Burst Mode operation voltage ripple is

observed on Trace A, while none is observed on Trace B.

Atlightloads,theLT1308Bwillbegintoskipalternatecycles.

The load point at which this occurs can be decreased by

increasing the inductor value. However, output ripple will

continue to be signiﬁcantly less than the LT1308A output

ripple. Further, theLT1308Bcanbeforcedintomicropower

mode, where I falls from 3mA to 200μA by sinking 40μA

Q

If the output load increases sufﬁciently, A1’s output

remains high, resulting in continuous operation. When the

LT1308A is running continuously, peak switch current is

or more out of the V pin. This stops switching by causing

C

A1’s output to go low.

controlled by V to regulate the output voltage. The switch

C

is turned on at the beginning of each switch cycle. When

the summation of a signal representing switch current

and a ramp generator (introduced to avoid subharmonic

oscillations at duty factors greater than 50%) exceeds the

TRACE A: LT1308A

V

, 100mV/DIV

OUT

AC COUPLED

TRACE B: LT1308B

V

, 100mV/DIV

OUT

AC COUPLED

V signal, comparator A2 changes state, resetting the ﬂip-

C

800mA

I

LOAD

ﬂop and turning off the switch. Output voltage increases

as switch current is increased. The output, attenuated

by a resistor divider, appears at the FB pin, closing the

overall loop. Frequency compensation is provided by an

50mA

1308 F03

200μs/DIV

(CIRCUIT OF FIGURE 1)

V

IN

= 3V

external series RC network connected between the V pin

Figure 3. LT1308A Exhibits Burst Mode Operation Output

Voltage Ripple at 50mA Load, LT1308B Does Not

C

and ground.

1308abfb

8

LT1308A/LT1308B

APPLICATIONS INFORMATION

WaveformsforaLT1308B5Vto12Vboostconverterusing

a 10μF ceramic output capacitor are pictured in Figures 4

and 5. In Figure 4, the converter is operating in continuous

mode, delivering a load current of approximately 500mA.

Thetoptraceistheoutput.Thevoltageincreasesasinduc-

tor current is dumped into the output capacitor during the

switchofftime,andthevoltagedecreaseswhentheswitch

is on. Ripple voltage is in this case due to capacitance,

as the ceramic capacitor has little ESR. The middle trace

is the switch voltage. This voltage alternates between a

LAYOUT HINTS

The LT1308A/LT1308B switch current at high speed, man-

dating careful attention to layout for proper performance.

You will not get advertised performance with careless

layout. Figure 6 shows recommended component place-

mentforanSO-8packageboost(step-up)converter.Follow

this closely in your PC layout. Note the direct path of the

switching loops. Input capacitor C1 must be placed close

(<5mm) to the IC package. As little as 10mm of wire or PC

trace from C to V will cause problems such as inability

IN

V

and V

plus the diode drop. The lower trace is

CESAT

OUT

to regulate or oscillation.

the switch current. At the beginning of the switch cycle,

the current is 1.2A. At the end of the switch on time, the

currenthasincreasedto2A,atwhichpointtheswitchturns

offandtheinductorcurrentﬂowsintotheoutputcapacitor

through the diode. Figure 5 depicts converter waveforms

at a light load. Here the converter operates in discontinu-

ous mode. The inductor current reaches zero during the

switch off time, resulting in some ringing at the switch

node. The ring frequency is set by switch capacitance,

diode capacitance and inductance. This ringing has little

energy, and its sinusoidal shape suggests it is free from

harmonics. Minimizing the copper area at the switch node

will prevent this from causing interference problems.

The negative terminal of output capacitor C2 should tie

close to the ground pin(s) of the LT1308A/LT1308B. Doing

this reduces dI/dt in the ground copper which keeps high

frequency spikes to a minimum. The DC/DC converter

groundshouldtietothePCboardgroundplaneatoneplace

only, to avoid introducing dI/dt in the ground plane.

LBI

LBO

GROUND PLANE

C1

+

V

IN

R1

1

2

3

4

8

V

OUT

7

6

5

LT1308A

LT1308B

L1

100mV/DIV

R2

SHUTDOWN

V

SW

10V/DIV

MULTIPLE

VIAs

+

I

D1

SW

500mA/DIV

C2

GND

1308 F04

V

OUT

500ns/DIV

Figure 4. 5V to 12V Boost Converter Waveforms in

Continuous Mode. 10μF Ceramic Capacitor Used at Output

1308 F04

Figure 6. Recommended Component Placement for SO-8

Package Boost Converter. Note Direct High Current Paths

V

OUT

20mV/DIV

Using Wide PC Traces. Minimize Trace Area at Pin 1 (V_C) and

Pin 2 (FB). Use Multiple Vias to Tie Pin 4 Copper to Ground

Plane. Use Vias at One Location Only to Avoid Introducing

Switching Currents into the Ground Plane

V

SW

10V/DIV

I

SW

500mA/DIV

Figure 7 shows recommended component placement for

a boost converter using the TSSOP package. Placement

is similar to the SO-8 package layout.

1308abfb

1308 F05

500ns/DIV

Figure 5. Converter Waveforms in Discontinuous Mode

9

LT1308A/LT1308B

APPLICATIONS INFORMATION

A SEPIC (Single-Ended Primary Inductance Converter)

schematic is shown in Figure 8. This converter topology

produces a regulated output over an input voltage range

that spans (i.e., can be higher or lower than) the output.

RecommendedcomponentplacementforanSO-8package

SEPIC is shown in Figure 9.

LBI

LBO

GROUND PLANE

C1

+

V

IN

R1

1

2

3

4

5

6

7

14

C2

13

12

11

10

9

4.7μF

CERAMIC

L1

R2

L1A

CTX10-2

D1

SHUTDOWN

V

IN

3V TO

10V

LT1308A

LT1308B

V

IN

SW

+

L1B

C1

47μF

MULTIPLE

VIAs

R1

309k

LT1308B

V

OUT

8

5V

SHUTDOWN

SHDN

FB

GND

500mA

V

C

R2

100k

+

D1

C3

220μF

6.3V

47k

680pF

C2

GND

V

OUT

C1: AVX TAJC476M016

C2: TAIYO YUDEN EMK325BJ475(X5R)

C3: AVX TPSD227M006

D1: IR 10BQ015

L1: COILTRONICS CTX10-2

1308A/B F08

1308 F07

Figure 7. Recommended Component

Placement for TSSOP Boost Converter.

Placement is Similar to Figure 4

Figure 8. SEPIC (Single-Ended Primary

Inductance Converter) Converts 3V to 10V

Input to a 5V/500mA Regulated Output

LBI

LBO

GROUND PLANE

C1

+

V

IN

R1

1

2

8

7

6

5

LT1308A

LT1308B

R2

SHUTDOWN

3

4

L1A

C2

L1B

MULTIPLE

VIAs

C3

+

GND

D1

V

OUT

1308 F09

Figure 9. Recommended Component Placement for SEPIC

1308abfb

10

LT1308A/LT1308B

APPLICATIONS INFORMATION

SHDN PIN

A cross plot of the low-battery detector is shown in

Figure 12. The LBI pin is swept with an input which var-

ies from 195mV to 205mV, and LBO (with a 100k pull-up

resistor) is displayed.

The LT1308A/LT1308B SHDN pin is improved over the

LT1308. The pin does not require tying to V to enable

IN

the device, but needs only a logic level signal. The voltage

on the SHDN pin can vary from 1V to 10V independent

of V . Further, ﬂoating this pin has the same effect as

IN

grounding, which is to shut the device down, reducing

current drain to 1μA or less.

V

LBO

1V/DIV

LOW-BATTERY DETECTOR

The low-battery detector on the LT1308A/LT1308B fea-

tures improved accuracy and drive capability compared

to the LT1308. The 200mV reference has an accuracy of

2% and the open-collector output can sink 50μA. The

LT1308A/LT1308B low-battery detector is a simple PNP

input gain stage with an open-collector NPN output. The

negativeinputofthegainstageistiedinternallytoa200mV

reference.ThepositiveinputistheLBIpin.Arrangementas

alow-batterydetectorisstraightforward. Figure10details

hookup. R1 and R2 need only be low enough in value so

that the bias current of the LBI pin doesn’t cause large

errors. For R2, 100k is adequate. The 200mV reference

can also be accessed as shown in Figure 11.

195

200

(mV)

205

1308 F12

V

LBI

Figure 12. Low-Battery Detector

Input/Output Characteristic

START-UP

TheLT1308A/LT1308Bcanstartupintoheavyloads,unlike

manyCMOSDC/DCconvertersthatderiveoperatingvoltage

from the output (a technique known as “bootstrapping”).

Figure 13 details start-up waveforms of Figure 1’s circuit

with a 20Ω load and V of 1.5V. Inductor current rises to

IN

3.5A as the output capacitor is charged. After the output

reaches 5V, inductor current is about 1A. In Figure 14, the

load is 5Ω and input voltage is 3V. Output voltage reaches

5V in 500μs after the device is enabled. Figure 15 shows

start-up behavior of Figure 5’s SEPIC circuit, driven from a

9V input with a 10Ω load. The output reaches 5V in about

1ms after the device is enabled.

5V

R1

V

IN

LT1308A

LT1308B

100k

LBI

+

–

LBO

TO PROCESSOR

R2

100k

200mV

V

– 200mV

2μA

LB

R1 =

INTERNAL

V

BAT

REFERENCE

GND

V

OUT

1308 F10

2V/DIV

I

L1

1A/DIV

Figure 10. Setting Low-Battery Detector Trip Point

V

SHDN

5V/DIV

200k

V

IN

2N3906

REF

LBO

LBI

1308 F13

1ms/DIV

V

BAT

LT1308A

LT1308B

V

200mV

+

Figure 13. 5V Boost Converter of Figure 1.

Start-Up from 1.5V Input into 20Ω Load

GND

10k

10μF

1308 F11

Figure 11. Accessing 200mV Reference

1308abfb

11

LT1308A/LT1308B

APPLICATIONS INFORMATION

whenoperatingfromabatterycomposedofalkalinecells.

Theinrushcurrentmaycausesufﬁciencyinternalvoltage

drop to trigger a low-battery indicator. A programmable

soft-start can be implemented with 4 discrete compo-

nents. A 5V to 12V boost converter using the LT1308B

V

OUT

1V/DIV

I

L1

2A/DIV

V

SHDN

is detailed in Figure 16. C4 differentiates V , causing

OUT

5V/DIV

a current to ﬂow into R3 as V

increases. When this

OUT

1308 F14

current exceeds 0.7V/33k, or 21μA, current ﬂows into

500μs/DIV

the base of Q1. Q1’s collector then pulls current out the

Figure 14. 5V Boost Converter of Figure 1.

Start-Up from 3V Input into 5Ω Load

V pin, creating a feedback loop where the slope of V

C

OUT

is limited as follows:

V

OUT

ΔV_OUT

Δt

0.7V

33k •C4

2V/DIV

=

I

SW

2A/DIV

With C4 = 33nF, V /t is limited to 640mV/ms. Start-up

OUT

waveformsforFigure16’scircuitarepicturedinFigure17.

Withoutthesoft-startcircuitimplemented,theinrushcur-

rentreaches3A.Thecircuitreachesﬁnaloutputvoltagein

approximately 250μs. Adding the soft-start components

reduces inductor current to less than 1A, as detailed in

Figure 18, while the time required to reach ﬁnal output

voltage increases to about 15ms. C4 can be adjusted to

achieve any output slew rate desired.

V

SHDN

5V/DIV

1308 F15

500μs/DIV

Figure 15. 5V SEPIC Start-Up from 9V Input into 10Ω Load

Soft-Start

In some cases it may be undesirable for the LT1308A/

LT1308B to operate at current limit during start-up, e.g.,

L1

4.7μH

D1

V

OUT

V

IN

12V

5V

500mA

V

IN

SW

+

SHDN

SHUTDOWN

C1

47μF

LT1308B

330pF

11.3k

100k

10k

C2

10μF

FB

GND

V

C

C4

33nF

R4

33k

R

C

Q1

47k

C

R3

33k

100pF

SOFT-START

COMPONENTS

C1: AVX TAJ476M010

1308 F16

C2: TAIYO YUDEN TMK432BJ106MM

D1: IR 10BQ015

L1: MURATA LQH6C4R7

Q1: 2N3904

Figure 16. 5V to 12V Boost Converter with Soft-Start Components Q1, C4, R3 and R4

1308abfb

12

LT1308A/LT1308B

APPLICATIONS INFORMATION

that copper loss is minimized. Acceptable inductance

values range between 2μH and 20μH, with 4.7μH best for

most applications. Lower value inductors are physically

smaller than higher value inductors for the same current

capability.

12V

V

OUT

5V/DIV

5V

I

L1

1A/DIV

V

SHDN

10V/DIV

Table 1 lists some inductors we have found to perform

well in LT1308A/LT1308B application circuits. This is not

an exclusive list.

1308 F17

50μs/DIV

Figure 17. Start-Up Waveforms of Figure 16’s Circuit

without Soft-Start Components

Table 1

VENDOR

Murata

PART NO.

LQH6C4R7

CDRH734R7

CTX5-1

VALUE

4.7μH

5μH

PHONE NO.

770-436-1300

847-956-0666

561-241-7876

847-639-6400

12V

V

OUT

Sumida

5V

Coiltronics

Coilcraft

LPO2506IB-472

4.7μH

I

L1

1A/DIV

V

Capacitors

SHDN

10V/DIV

Equivalent Series Resistance (ESR) is the main issue

regarding selection of capacitors, especially the output

capacitors.

1308 F18

5ms/DIV

Figure 18. Start-Up Waveforms of Figure 16’s Circuit

with Soft-Start Components Added

The output capacitors speciﬁed for use with the LT1308A/

LT1308B circuits have low ESR and are speciﬁcally

designed for power supply applications. Output voltage

ripple of a boost converter is equal to ESR multiplied by

switchcurrent.TheperformanceoftheAVXTPSD227M006

220μF tantalum can be evaluated by referring to Figure 3.

Whentheloadis800mA,thepeakswitchcurrentisapproxi-

COMPONENT SELECTION

Diodes

We have found ON Semiconductor MBRS130 and Inter-

national Rectiﬁer 10BQ015 to perform well. For applica-

tions where V

exceeds 30V, use 40V diodes such as

mately 2A. Output voltage ripple is about 60mV , so the

OUT

P-P

MBRS140 or 10BQ040.

ESR of the output capacitor is 60mV/2A or 0.03Ω. Ripple

can be further reduced by paralleling ceramic units.

Heightlimitedapplicationsmaybeneﬁtfromtheuseofthe

MBRM120. This component is only 1mm tall and offers

performance similar to the MBRS130.

Table 2 lists some capacitors we have found to perform

well in the LT1308A/LT1308B application circuits. This is

not an exclusive list.

Inductors

Table 2

SuitableinductorsforusewiththeLT1308A/LT1308Bmust

fulﬁll two requirements. First, the inductor must be able

to handle current of 2A steady-state, as well as support

transient and start-up current over 3A without inductance

decreasing by more than 50% to 60%. Second, the DCR

of the inductor should have low DCR, under 0.05Ω so

VENDOR

AVX

SERIES

TPS

PART NO.

VALUE

PHONE NO.

TPSD227M006 220μF, 6V 803-448-9411

TPSD107M010 100μF, 10V 803-448-9411

LMK432BJ226 22μF, 10V 408-573-4150

TMK432BJ106 10μF, 25V 408-573-4150

AVX

TPS

Taiyo Yuden

X5R

1308abfb

13

LT1308A/LT1308B

APPLICATIONS INFORMATION

Ceramic Capacitors

Without C , load step response is pictured in Figure 22.

PL

Although the output settles faster than the tantalum case,

thereisappreciableringing,againsuggestingphasemargin

islow.Figure23depictsloadstepresponseusingthe10μF

Multilayer ceramic capacitors have become popular, due

to their small size, low cost, and near-zero ESR. Ceramic

capacitors can be used successfully in LT1308A/LT1308B

designs provided loop stability is considered. A tantalum

capacitor has some ESR and this causes an "ESR zero" in

the regulator loop. This zero is beneﬁcial to loop stability.

Ceramics do not have appreciable ESR, so the zero is lost

when they are used. However, the LT1308A/LT1308B have

ceramic output capacitor and C . Response is clean and

PL

no ringing is evident. Ceramic capacitors have the added

beneﬁt of lowering ripple at the switching frequency due

to their very low ESR. By applying C in tandem with the

PL

series RC at the V pin, loop response can be tailored to

C

optimize response using ceramic output capacitors.

external compensation pin (V ) so component values can

C

be adjusted to achieve stability. A phase lead capacitor can

also be used to tune up load step response to optimum

levels, as detailed in the following paragraphs.

V

OUT

500mV/DIV

I

L1

Figure 19 details a 5V to 12V boost converter using either

a tantalum or ceramic capacitor for C2. The input capaci-

tor has little effect on loop stability, as long as minimum

capacitance requirements are met. The phase lead capaci-

1A/DIV

500mA

50mA

LOAD

CURRENT

1308 F20

200μs/DIV

tor C parallels feedback resistor R1. Figure 20 shows

PL

load step response of a 50mA to 500mA load step using a

47μF tantalum capacitor at the output. Without the phase

lead capacitor, there is some ringing, suggesting the

Figure 20. Load Step Response of LT1308B 5V to 12V

Boost Converter with 47μF Tantalum Output Capacitor

phase margin is low. C is then added, and response to

PL

V

OUT

the same load step is pictured in Figure 21. Some phase

margin is restored, improving the response. Next, C2 is

replaced by a 10μF, X5R dielectric, ceramic capacitor.

500mV/DIV

I

L1

4.7μH

1A/DIV

D1

V

OUT

V

IN

12V

5V

500mA

50mA

500mA

LOAD

CURRENT

1308 F21

200μs/DIV

V

IN

SW

SHDN

Figure 21. Load Step Response with 47μF Tantalum

Output Capacitor and Phase Lead Capacitor C_PL

C

R1

100k

PL

LT1308B

R3

10k

330pF

FB

GND

C2

V

C

V

+

OUT

C1

47μF

500mV/DIV

R2

11.3k

47k

100pF

I

L1

1A/DIV

500mA

50mA

LOAD

CURRENT

C1: AVX TAJC476M010

C2: AVX TPSD476M016 (47μF) OR

TAIYO YUDEN TMK432BJ106MM (10μF)

D1: IR 10BQ015

L1: MURATA LQH6C4R7

1308 F19

1308 F22

200μs/DIV

Figure 22. Load Step Response with 10μF X5R

Ceramic Output Capacitor

Figure 19. 5V to 12V Boost Converter

1308abfb

14

LT1308A/LT1308B

APPLICATIONS INFORMATION

V

OUT

V

= 4.2V

500mV/DIV

IN

V

OUT

= 3.6V

I

L1

1A/DIV

V

= 3V

OUT

IN

I

LOAD

1A

1mA

500mA

50mA

LOAD

CURRENT

1308 F23

1308 F25

200μs/DIV

V

TRACES =

OUT

200mV/DIV

Figure 23. Load Step Response with 10μF X5R

Ceramic Output Capacitor and C_PL

Figure 25. LT1308A Li-Ion to 5V Boost Converter

Transient Response to 1A Load Step

GSM AND CDMA PHONES

The LT1308A/LT1308B are suitable for converting a single

Li-Ion cell to 5V for powering RF power stages in GSM or

CDMA phones. Improvements in the LT1308A/LT1308B

error ampliﬁers allow external compensation values to be

reduced, resulting in faster transient response compared

to the LT1308. The circuit of Figure 24 (same as Figure 1,

printed again for convenience) provides a 5V, 1A output

from a Li-Ion cell. Figure 25 details transient response at

V

OUT

V

= 4.2V

IN

V

OUT

V

= 3.6V

V

OUT

= 3V

IN

I

LOAD

1A

10mA

1308 F26

100μs/DIV

V

TRACES =

OUT

theLT1308AoperatingataV of4.2V, 3.6Vand3V. Ripple

IN

200mV/DIV

voltage in Burst Mode operation can be seen at 10mA

load. Figure 26 shows transient response of the LT1308B

under the same conditions. Note the lack of Burst Mode

ripple at 10mA load.

Figure 26. LT1308B Li-Ion to 5V Boost

Converter Transient Response to 1A Load Step

L1

4.7μH

D1

5V

1A

V

IN

SW

+

C1

47μF

R1

LT1308B

309k

+

Li-Ion

CELL

C2

220μF

SHUTDOWN

SHDN

FB

GND

V

C

R2

100k

47k

100pF

C1: AVX TAJC476M010

C2: AVX TPSD227M006

D1: IR 10BQ015

L1: MURATA LQH6N4R7

1308A/B F24

Figure 24. Li-Ion to 5V Boost Converter Delivers 1A

1308abfb

15

LT1308A/LT1308B

TYPICAL APPLICATIONS

Triple Output TFTLCD Bias Supply

D2

V

OFF

–9V

C4

10mA

1μF

D3

V

ON

27V

C5

1μF

0.22μF

15mA

D4

C6

1μF

0.22μF

L1

4.7μH

D1

V

IN

5V

AV

DD

6

5

10V

V

SW

IN

500mA

3

1

SHDN

76.8k

10.7k

C2, C3

10μF

×2

C1

LT1308B

4.7μF

2

FB

V

C

GND

4

220k

100pF

C1:TAIYO-YUDEN JMK212BJ475MG

C2, C3:TAIYO-YUDEN LMK325BJ106MN

1308 TA02

C4, C5, C6:TAIYO-YUDEN EMK212BJ105MG

D1: MBRM120

D2,D3,D4: BAT54S

L1: TOKO 817FY-4R7M

TFTLCD Bias Supply Transient Response

AV

DD

500mV/DIV

V

ON

500mV/DIV

V

OFF

500mV/DIV

800mA

I

LOAD

200mA

100μs/DIV

1308abfb

16

LT1308A/LT1308B

TYPICAL APPLICATIONS

40nF EL Panel Driver

T1

1:12

D2

D3

V

BAT

3V TO 6V

4

6

+

3

C1

47μF

1

D1

3.3V

REGULATED

1μF

2M

100k

V

SW

IN

4.3M

Q1

LBO

FB

47k

LT1308A

17k

C2

324k

150k

1μF

200V

LBI

V

SHUTDOWN

SHDN

GND

C

Q2

400V

EL PANEL

≤40nF

100pF

47pF

22nF

49.9k

3.3k

10k

1308 TA03

Q1: MMBT3906

Q2: ZETEX FCX458

T1: MIDCOM 31105

C1: AVX TAJC476M010

C2: VITRAMON VJ225Y105KXCAT

D1: BAT54

D2, D3: BAV21

High Voltage Supply 350V at 1.2mA

SEPIC Converts 3V to 10V Input to a 5V/500mA Regulated Output

10nF

250V

D3

V

OUT

C2

350V

4.7μF

L1A

1.2mA

10nF

250V

CERAMIC

D1

T1

1:12

D2

CTX10-2

LT1308B

V

IN

D1

V

3V TO

10V

IN

2.7V TO 6V

+

3

4

6

C1

47μF

V

SW

IN

10nF

250V

+

L1B

C1

1

47μF

R1

309k

V

OUT

D4

5V

SHUTDOWN

SHDN

FB

GND

500mA

V

C

R2

100k

V

SW

IN

+

C3

220μF

6.3V

47k

680pF

SHUTDOWN

SHDN

LT1308A

10M

C1: AVX TAJC476M016

C2: TAIYO YUDEN EMK325BJ475(X5R)

C3: AVX TPSD227M006

D1: IR 10BQ015

L1: COILTRONICS CTX10-2

FB

V

C

1308A/B TA05

GND

47k

10nF

100pF

34.8k

D1, D2, D3: BAV21 200mA, 250V

D4: MBR0540

1308 TA04

T1: MIDCOM 31105R L = 1.5μH

P

1308abfb

17

LT1308A/LT1308B

PACKAGE DESCRIPTION

S8 Package

8-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610)

.189 – .197

(4.801 – 5.004)

NOTE 3

.045 .005

.050 BSC

7

5

8

6

.245

MIN

.160 .005

.150 – .157

(3.810 – 3.988)

NOTE 3

.228 – .244

(5.791 – 6.197)

.030 .005

TYP

1

2

3

4

RECOMMENDED SOLDER PAD LAYOUT

.010 – .020

(0.254 – 0.508)

× 45°

.053 – .069

(1.346 – 1.752)

.004 – .010

(0.101 – 0.254)

.008 – .010

(0.203 – 0.254)

0°– 8° TYP

.016 – .050

(0.406 – 1.270)

.050

(1.270)

BSC

.014 – .019

(0.355 – 0.483)

TYP

NOTE:

INCHES

1. DIMENSIONS IN

(MILLIMETERS)

2. DRAWING NOT TO SCALE

3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

SO8 0303

F Package

14-Lead Plastic TSSOP (4.4mm)

(Reference LTC DWG # 05-08-1650)

4.90 – 5.10*

(.193 – .201)

14 13 12 11 10

9 8

1.05 0.10

4.50 0.10

6.60 0.10

6.40

(.252)

BSC

0.45 0.05

0.65 BSC

5

7

6

1

2

3

4

RECOMMENDED SOLDER PAD LAYOUT

1.10

(.0433)

MAX

4.30 – 4.50**

(.169 – .177)

0.25

REF

0° – 8°

0.65

(.0256)

BSC

0.09 – 0.20

(.0035 – .0079)

0.50 – 0.75

(.020 – .030)

0.05 – 0.15

(.002 – .006)

F14 TSSOP 0204

0.19 – 0.30

(.0075 – .0118)

TYP

NOTE:

1. CONTROLLING DIMENSION: MILLIMETERS

MILLIMETERS

2. DIMENSIONS ARE IN

(INCHES)

3. DRAWING NOT TO SCALE

*DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED .152mm (.006") PER SIDE

**DIMENSIONS DO NOT INCLUDE INTERLEAD FLASH. INTERLEAD

FLASH SHALL NOT EXCEED .254mm (.010") PER SIDE

1308abfb

18

LT1308A/LT1308B

REVISION HISTORY ^{(Revision history begins at Rev B)}

REV

DATE

DESCRIPTION

PAGE NUMBER

B

12/10 Obsoleted F Package

2

1308abfb

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.

19

LT1308A/LT1308B

TYPICAL APPLICATION

Li-Ion to 12V/300mA Step-Up DC/DC Converter

L1

4.7μH

D1

2.7V TO 4.2V

12V

300mA

V

IN

SW

+

C1

47μF

R1

887k

LT1308B

+

Li-Ion

CELL

C2

100μF

SHUTDOWN

SHDN

FB

GND

V

C

R2

100k

47k

330pF

C1: AVX TAJC476M010

C2: AVX TPSD107M016

D1: IR 10BQ015

L1: MURATA LQH6C4R7

1308A/B TA01

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

LT1302

High Output Current Micropower DC/DC Converter

2-Cell Micropower DC/DC Converter

5V/600mA from 2V, 2A Internal Switch, 200μA I

Q

LT1304

5V/200mA, Low-Battery Detector Active in Shutdown

3.3V at 75mA from One Cell, MSOP Package

LT1307/LT1307B

LT1316

Single Cell, Micropower, 600kHz PWM DC/DC Converters

Burst Mode Operation DC/DC with Programmable Current Limit

Micropower, 600kHz PWM DC/DC Converters

Micropower Step-Down DC/DC Converter

1.5V Minimum, Precise Control of Peak Current Limit

LT1317/LT1317B

LTC^®1474

LTC1516

LTC1522

LT1610

100μA I , Operate with V as Low as 1.5V

Q IN

94% Efﬁciency, 10μA I , 9V to 5V at 250mA

Q

2-Cell to 5V Regulated Charge Pump

12μA I , No Inudctors, 5V at 50mA from 3V Input

Q

Micropower, 5V Charge Pump DC/DC Converter

Single-Cell Micropower DC/DC Converter

Regulated 5V 4% Output, 20mA from 3V Input

3V at 30mA from 1V, 1.7MHz Fixed Frequency

–5V at 150mA from 5V Input, Tiny SOT-23 package

5V at 200mA from 4.4V Input, Tiny SOT-23 package

LT1611

Inverting 1.4MHz Switching Regulator in 5-Lead SOT-23

1.4MHz Switching Regulator in 5-Lead SOT-23

Micropower Step-Up DC/DC in 5-Lead SOT-23

Micropower Inverting DC/DC Converter in SOT-23

Doubler Charge Pump with Low Noise LDO

600kHz, 1A Switch PWM DC/DC Converter

1.1MHz, 1A Switch DC/DC Converter

LT1613

LT1615

20μA I , 36V, 350mA Switch

Q

LT1617

V

IN

= 1V to 15V; V

to –34V

OUT

LTC1682

LT1949

Adjustable or Fixed 3.3V, 5V Outputs, 60μV

Output Noise

RMS

1.1A, 0.5Ω, 30V Internal Switch, V as Low as 1.5V

IN

LT1949-1

1.1MHz Version of LT1949

1308abfb

LT 1210 REV B • PRINTED IN USA

20 ^{LinearTechnology Corporation}

1630 McCarthy Blvd., Milpitas, CA 95035-7417

●

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


型号：	LT1308BCS8#PBF
厂家：	Linear
描述：	LT1308A and B - Single Cell High Current Micropower 600kHz Boost DC/DC Converter; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C 开关光电二极管
文件：	总20页 (文件大小：381K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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