LT1307CS8#TRPBF_技术文档

LT1307/ LT1307B

Sing le Ce ll Mic ro p o we r

600kHz PWM DC/ DC Co nve rte rs

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DESCRIPTION

FEATURES

The LT^®1307/LT1307B are micropower, fixed frequency

DC/DC converters that operate from an input voltage as

low as 1V. First in the industry to achieve true current

mode PWM performance from a single cell supply, the

LT1307 features automatic shifting to power saving Burst

Mode operation at light loads. High efficiency is main-

tained over a broad 100µA to 100mA load range. The

LT1307B does not shift into Burst Mode operation at light

loads, eliminating low frequency output ripple at the

expenseoflightloadefficiency. Thedevices containalow-

battery detector with a 200mV reference and shut down to

less than 5µA. No load quiescent current of the LT1307 is

50µAandtheinternalNPNpowerswitchhandles a500mA

current with a voltage drop of just 295mV.

■

Uses Small Ceramic Capacitors

50µA Quiescent Current (LT1307)

1mA Quiescent Current (LT1307B)

Operates with V as Low as 1V

■

IN

■

600kHz Fixed Frequency Operation

Starts into Full Load

Low Shutdown Current: 3µA

Low-Battery Detector

3.3V at 75mA from a Single Cell

Automatic Burst Mode^TMOperation at

Light Load (LT1307)

■

Continuous Switching at Light Load (LT1307B)

Low V_CESATSwitch: 295mV at 500mA

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Unlike competitive devices, large electrolytic capacitors

are not required with the LT1307/LT1307B in single cell

applications. The high frequency (600kHz) switching al-

lows the use of tiny surface mount multilayer ceramic

(MLC) capacitors along with small surface mount induc-

tors. The devices work with just 10µF of output capaci-

tance and require only 1µF of input bypassing.

APPLICATIONS

■

Pagers

Cordless Telephones

GPS Receivers

Battery Backup

Portable Electronic Equipment

Glucose Meters

Diagnostic Medical Instrumentation

■

The LT1307/LT1307B are available in 8-lead MSOP, PDIP

and SO packages.

■

, LTC and LT are registered trademarks of Linear Technology Corporation.

Burst Mode is a trademark of Linear Technology Corporation.

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TYPICAL APPLICATION

Single Cell to 3.3V Converter Efficiency

L1

10µH

D1

90

C1: MURATA-ERIE GRM235Y5V105Z01

MARCON THCS50E1E105Z

V

SW

FB

IN

TOKIN 1E105ZY5U-C103-F

C2: MURATA-ERIE GRM235Y5V106Z01

C1

1µF

3.3V

75mA

80

LBI

V

IN

= 1.5V

V

MARCON THCS50E1E105Z

TOKIN 1E106ZY5U-C304-F

R1

1.02M

1%

LT1307

1.5V

CELL

SHUTDOWN SHDN

LBO

GND

= 1V

D1: MOTOROLA MBR0520L

L1: COILCRAFT D01608C-103

SUMIDA CD43-100

IN

V

C

C2

10µF

70

60

50

V

IN

= 1.25V

R2

604k

1%

100k

680pF

MURATA ERIE LQH3C100

FOR 5V OUTPUT: R1 = 1M, R2 = 329k

1307 F01

0.1

1

10

100

Figure 1. Single Cell to 3.3V Boost Converter

LOAD CURRENT (mA)

1307 TA01

1

LT1307/ LT1307B

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ABSOLUTE AXI U RATI GS

V , SHDN, LBO Voltage ......................................... 12V

SW Voltage ............................................................. 30V

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

Operating Temperature Range

IN

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

Commercial (Note 1) ......................... –20°C to 70°C

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

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

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

IN

V_CVoltage ................................................................ 2V

LBI Voltage ............................................ 0V ≤ V_LBI≤ 1V

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

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PACKAGE RDER I FOR ATIO

ORDER PART

NUMBER

ORDER PART

NUMBER

TOP VIEW

V

1

2

3

4

8

7

6

5

LBO

LBI

LT1307CN8

LT1307CS8

LT1307IS8

LT1307BCS8

LT1307BIS8

TOP VIEW

C

LT1307CMS8

LT1307BCMS8

V

1

8 LBO

7 LBI

FB

SHDN

GND

C

FB 2

SHDN 3

GND 4

V

IN

6 V

IN

5 SW

SW

MS8 PACKAGE

8-LEAD PLASTIC MSOP

N8 PACKAGE

8-LEAD PDIP

S8 PACKAGE

8-LEAD PLASTIC SO

T

_JMAX= 125°C, θ_JA= 160°C/W

T

_JMAX= 125°C, θ_JA= 100°C/W (N8)

MS8 PART MARKING

S8 PART MARKING

T_JMAX= 125°C, θ_JA= 120°C/W (S8)

BU

BF

1307

1307B

1307I

1307BI

Consult factory for Military grade parts.

ELECTRICAL CHARACTERISTICS

Commercial Grade 0°C to 70°C. V = 1.1V, V_SHDN= V , T_A= 25°C, LT1307/LT1307B unless otherwise noted.

IN

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

I

Q

Quiescent Current

Not Switching (LT1307)

Not Switching (LT1307B)

●

50

1.0

1

90

1.5

3

µA

mA

µA

V

= 0V

SHDN

V

Feedback Voltage

●

1.20

1.22

27

1.24

60

V

FB

I

B

FB Pin Bias Current (Note 2)

Reference Line Regulation

V

= V

REF

nA

FB

1V ≤ V ≤ 2V (25°C, 0°C)

1V ≤ V ≤ 2V (70°C)

2V ≤ V ≤ 5V

0.6

1.1

1.5

0.8

%/V

IN

●

0.3

IN

Minimum Input Voltage

Input Voltage Range

0.92

1

5

V

●

1

g

m

Error Amp Transconductance

Error Amp Voltage Gain

∆I = 5µA

25

35

65

µmhos

A

V

25°C, 0°C

70°C

35

30

100

V/V

f

Switching Frequency

●

550

600

750

kHz

OSC

2

LT1307/ LT1307B

ELECTRICAL CHARACTERISTICS

Commercial Grade 0°C to 70°C. V = 1.1V, V_SHDN= V , T_A= 25°C unless otherwise noted.

IN

SYMBOL PARAMETER

Maximum Duty Cycle

CONDITIONS

MIN

TYP

MAX

UNITS

25°C, 0°C

70°C

80

76

84

%

Switch Current Limit (Note 3)

Switch V

DC = 40%

DC = 75%

●

0.6

0.5

1.25

A

I

SW

= 500mA (25°C, 0°C)

= 500mA (70°C)

295

350

400

mV

CESAT

I

SW

Burst Mode Operation Switch Current Limit

(LT1307 Only)

L = 10µH

L = 22µH

100

50

mA

Shutdown Pin Current

V

SHDN

= V

= 0V

●

2.5

–1.5

4.0

–2.5

µA

SHDN

IN

LBI Threshold Voltage

LBO Output Low

●

190

200

0.1

210

0.25

0.1

mV

V

I

= 10µA

SINK

LBO Leakage Current

V

= 250mV, V = 5V

0.01

5

µA

nA

LBI

LBO

LBI Input Bias Current (Note 4)

Low-Battery Detector Gain

V

= 150mV

25

LBI

1MΩ Load (25°C, 0°C)

1MΩ Load (70°C)

1000

500

3000

V/V

Switch Leakage Current

Reverse Battery Current

V

= 5V

●

0.01

750

3

µA

SW

(Note 5)

mA

Commercial Grade T_A= –20°C, V = 1.1V, V_SHDN= V , unless otherwise noted (Note 1).

IN

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

I

Q

Quiescent Current

V

= 1.3V, Not Switching (LT1307)

= 1.3V, Not Switching (LT1307B)

= 0V

50

1.1

1

100

1.6

3

µA

mA

µA

FB

V

FB

V

SHDN

V

Feedback Voltage

1.195

25

1.22

35

1.245

65

V

µmhos

V/V

FB

g

Error Amp Transconductance

Error Amp Voltage Gain

Switching Frequency

∆I = 5µA

m

A

V

35

100

600

84

f

500

80

750

350

kHz

OSC

Maximum Duty Cycle

%

Switch V

I

SW

= 500mA, V = 1.2V

250

mV

CESAT

IN

Shutdown Pin Current

V

SHDN

= V

= 0V

2.5

–1.5

4.0

–2.5

µA

SHDN

IN

LBI Threshold Voltage

186

200

210

mV

3

LT1307/ LT1307B

ELECTRICAL CHARACTERISTICS

Industrial Grade –40°C to 85°C. V = 1.1V, V_SHDN= V , LT1307/LT1307B unless otherwise noted.

IN

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

I

Q

Quiescent Current

V

= 1.3V, Not Switching (LT1307)

= 1.3V, Not Switching (LT1307B)

= 0V

●

50

1

100

1.8

3

µA

mA

µA

FB

V

FB

V

SHDN

V

Feedback Voltage

●

1.195

10

1.22

27

1.245

100

V

FB

I

B

FB Pin Bias Current (Note 2)

Reference Line Regulation

V

= V

REF

nA

FB

1V ≤ V ≤ 2V (–40°C)

1V ≤ V ≤ 2V (85°C)

2V ≤ V ≤ 5V

0.6

1.1

3.2

0.8

%/V

IN

●

0.3

IN

Minimum Input Voltage

–40°C

85°C

1.1

0.8

1.2

1.0

V

Input Voltage Range

●

5

V

g

Error Amp Transconductance

Error Amp Voltage Gain

∆I = 5µA

25

35

65

µmhos

m

A

V

–40°C

85°C

35

30

V/V

f

Switching Frequency

Maximum Duty Cycle

●

500

600

750

kHz

OSC

–40°C

85°C

80

75

84

80

%

Switch Current Limit (Note 3)

DC = 40%

DC = 75%

0.6

0.5

1.25

A

Switch V

I

= 500mA, V = 1.2V (–40°C)

= 500mA (85°C)

250

330

350

400

mV

CESAT

SW

IN

I

SW

Burst Mode Operation Switch Current Limit

(LT1307 Only)

L = 10µH

L = 22µH

100

50

mA

Shutdown Pin Current

V

SHDN

= V

= 0V

●

2.5

–1.5

4.0

–2.5

µA

SHDN

IN

LBI Threshold Voltage

LBO Output Low

●

186

200

0.1

5

210

0.25

0.3

mV

V

I

= 10µA

SINK

LBO Leakage Current

V

= 250mV, V = 5V

µA

nA

LBI

LBO

LBI Input Bias Current (Note 4)

Low-Battery Detector Gain

V

= 150mV

30

LBI

1MΩ Load (–40°C)

1MΩ Load (85°C)

1000

400

6000

V/V

Switch Leakage Current

V

SW

= 5V

●

0.01

3

µA

The

●

denotes specifications which apply over the full operating

Note 2: Bias current flows into FB pin.

temperature range.

Note 3: Switch current limit guaranteed by design and/or correlation to

Note 1: Specifications for commercial (C) grade devices are guaranteed

but not tested at –20°C. MS8 package devices are designed for and

intended to meet commercial temperature range specifications but are not

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

Note 4: Bias current flows out of LBI pin.

Note 5: The LT1307 will withstand continuous application of 1.6V applied

tested at – 20°C or 0°C.

to the GND pin while V and SW are grounded.

IN

4

LT1307/ LT1307B

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TYPICAL PERFORMANCE CHARACTERISTICS

3.3V Output Efficiency, Circuit of

Figure 1 (LT1307B)

5V Output Efficiency, Circuit of

Figure 1 (LT1307B)

5V Output Efficiency, Circuit of

Figure 1 (LT1307)

90

80

70

60

50

90

80

70

60

50

40

30

20

10

90

80

70

60

50

40

30

20

10

V

IN

= 1.5V

V

IN

= 1V

V

IN

= 1.25V

V

IN

= 1.25V

V

IN

= 1V

V

IN

= 1.00V

V

IN

= 1.25V

V

IN

= 1.5V

V

IN

= 1.5V

10

1

LOAD CURRENT (mA)

100

200

0.1

1

10

100

0.1

1

10

100

LOAD CURRENT (mA)

LT1307 • G01

1307 G02

LT1307 • TPC03

Feedback Bias Current vs

Temperature

LBI Bias Current vs Temperature

Quiescent Current vs Temperature

50

40

30

20

80

16

14

12

10

8

V

IN

= 1.1V

70

60

50

40

30

20

10

0

6

4

10

0

2

0

–25

0

50

–50

0

25

50

75

100

–25

0

50

–50

75

100

–50

75

100

25

–25

25

TEMPERATURE (°C)

LT1307 • TPC04

LTC1307 • TPC05

LT1307 • TPC06

Shutdown Pin Bias Current vs

Input Voltage

Switch V_CESATvs Current

Quiescent Current in Shutdown

10

8

10

16

12

8

500

400

300

200

T

= 25°C

A

6

4

2

4

100

0

1

2

3

4

5

0

1

2

3

4

5

0

200

300

400

500

600

100

SWITCH CURRENT (mA)

INPUT VOLTAGE (V)

LT1307 • TPC07

LT1307 • TPC08

LT1307 • TPC09

5

LT1307/ LT1307B

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TYPICAL PERFORMANCE CHARACTERISTICS

Oscillator Frequency vs

Input Voltage

Feedback Voltage vs

Temperature

LBI Reference vs Temperature

1.230

1.225

1.220

1.215

1.210

1.205

1.200

900

800

700

600

500

400

210

208

206

204

202

200

198

196

194

192

190

25°C

85°C

–40°C

–50

0

25

50

75

100

–25

3

1

2

4

5

–50

–25

25

50

75

100

0

TEMPERATURE (°C)

INPUT VOLTAGE (V)

LT1307 • TPC10

LT1307 • TPC12

LT1307 • TPC11

Transient Response (LT1307)

Transient Response (LT1307B)

Load Regulation (LT1307)

V_OUT

200mV/DIV

AC COUPLED

V

OUT

200mV/DIV

AC COUPLED

V_OUT

50mV/DIV

DC

COUPLED

OFFSET

ADDED

I_L

200mA/DIV

55mA

I_LOAD

55mA

I_LOAD

5mA

V

_IN= 1.25V

500µs/DIV

1307 G13

V

_IN= 1.25V

500µs/DIV

1307 G14

V

_IN= 0.92V

I_LOAD10mA/DIV

1307 G15

V_OUT= 3.3V

Load Regulation (LT1307)

V

OUT

V

OUT

V

OUT

50mV/DIV

DC

50mV/DIV

DC

COUPLED

OFFSET

ADDED

COUPLED

OFFSET

ADDED

COUPLED

OFFSET

ADDED

V_IN= 1.15V

I_LOAD20mA/DIV

1307 G17

V_IN= 1V

I_LOAD10mA/DIV

1307 G18

V_IN= 1V

I_LOAD20mA/DIV

1307 G16

V_OUT= 3.3V

V_OUT= 5V

V_OUT= 3.3V

Circuit Operation, L = 10µH

(LT1307)

Circuit Operation, L = 22µH

(LT1307)

Load Regulation (LT1307)

V_OUT

50mV/DIV

AC COUPLED

V_OUT

50mV/DIV

AC COUPLED

V

OUT

50mV/DIV

DC

COUPLED

OFFSET

ADDED

V

SW

V

5V/DIV

SW

5V/DIV

I_L

100mA/DIV

V

_IN= 1.25V

V_OUT= 5V

_LOAD= 1.5mA

100µs/DIV

1307 G20

V

_IN= 1.25V

V_OUT= 5V

I_LOAD= 1.5mA

100µs/DIV

1307 G21

V

_IN= 1.15V

I_LOAD10mA/DIV

1307 G19

V_OUT= 5V

I

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LT1307/ LT1307B

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PIN FUNCTIONS

V (Pin 1): Compensation Pin for Error Amplifier. Con-

C

SW (Pin 5): Switch Pin. Connect inductor/diode here.

nect a series RC from this pin to ground. Typical values

Minimize trace area at this pin to keep EMI down.

are 100kΩ and 680pF. Minimize trace area at V .

C

V (Pin 6): Supply Pin. Must have 1µF ceramic bypass

IN

FB (Pin 2): Feedback Pin. Reference voltage is 1.22V.

Connect resistor divider tap here. Minimize trace area at

FB. Set V_OUTaccording to: V_OUT= 1.22V(1 + R1/R2).

capacitor right at the pin, connected directly to ground.

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

ence. Voltage on LBI must stay between ground and

SHDN (Pin 3): Shutdown. Ground this pin to turn off 700mV.

switcher. MustbetiedtoV (orhighervoltage)toenable

switcher. Do not float the SHDN pin.

IN

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

tor, can sink 10µA. A 1MΩ pull-up is recommended.

GND (Pin 4): Ground. Connect directly to local ground

plane.

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BLOCK DIAGRAM

V

IN

6

V

IN

R5

R6

40k

SHDN

+

–

V

C

SHUTDOWN

3

g

1

m

V

OUT

LBI

7

R1

ERROR

AMPLIFIER

+

–

+

–

(EXTERNAL)

FB

2

LBO

8

Q1

Q2

×10

*

FB

ENABLE

200mV

R2

BIAS

R3

30k

A4

A1

(EXTERNAL)

R4

140k

SW

5

COMPARATOR

–

DRIVER

FF

RAMP

GENERATOR

Q3

R

Q

+

Σ

+

S

A2

+

A = 3

–

0.15Ω

600kHz

OSCILLATOR

4

GND

1307 F02

*HYSTERESIS IN LT1307 ONLY

Figure 2. LT1307/LT1307B Block Diagram

7

LT1307/ LT1307B

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APPLICATIONS INFORMATION

OPERATION

200mV. There is no hysteresis in A4, allowing it to be used

as an amplifier in some applications. The entire device is

disabled when the SHDN pin is brought low. To enable the

The LT1307 combines a current mode, fixed frequency

PWMarchitecturewithBurstModemicropoweroperation

to maintain high efficiency at light loads. Operation can

best be 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. When

converter, SHDN must be at V or at a higher voltage.

IN

The LT1307B differs from the LT1307 in that there is no

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

set lower than on the LT1307 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.

This results intheabsenceoflowfrequencyoutputvoltage

ripple at the expense of efficiency.

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

IN

80mV drop across R5 and R6, forward biases Q1 and Q2’s

base collector junctions to 300mV. Because this is not

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

The difference between the two devices is clearly illus-

trated in Figures 3 and 4. The top two traces in Figure 3

show an LT1307/LT1307B circuit, using the components

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

1.25V.Loadcurrentis steppedfrom1mAto41mAforboth

circuits. Low frequency Burst Mode operation voltage

ripple is observed on Trace A, while none is observed on

decrease. When V reaches the bias voltage on hysteretic

C

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

50µA. As output loading causes the FB voltage to de-

crease, A1’s output goes high, enabling the rest of the IC.

Switch current is limited to approximately 100mA initially

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

voltage (and FB voltage) will increase until A1’s output

goes low, turning off the rest of the LT1307. Low fre-

quency ripple voltage appears at the output. The ripple

frequencyis dependentonloadcurrentandoutputcapaci-

tance. This Burst Mode operation keeps the output regu-

lated and reduces average current into the IC, resulting in

high efficiency even at load currents of 100µA or less.

LT1307

V

OUT

TRACE A

500mV/DIV

AC COUPLED

LT1307B

V

OUT

TRACE B

500mV/DIV

AC COUPLED

41mA

I_L

1mA

V_IN= 1.25V

1ms/DIV

1307 F03

V

_OUT= 5V

If the output load increases sufficiently, A1’s output re-

mains high, resulting in continuous operation. When the

LT1307 is running continuously, peak switch current is

Figure 3. LT1307 Exhibits Burst Mode Operation Ripple at

1mA Load, LT1307B Does Not

controlled by V to regulate the output voltage. The switch

C

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

thesummationofasignalrepresentingswitchcurrentand

a ramp generator (introduced to avoid subharmonic oscil-

LT1307

V

OUT

TRACE A

200mV/DIV

AC COUPLED

lations at duty factors greater than 50%) exceeds the V

C

LT1307B

V

OUT

signal, comparator A2 changes state, resetting the flip-

flopandturningofftheswitch.Outputvoltageincreases 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 external

TRACE B

200mV/DIV

AC COUPLED

45mA

I_L

5mA

V_IN= 1.5V

500µs/DIV

1307 F04

V_OUT= 5V

Figure 4. At Higher Loading and a 1.5V Supply, LT1307

Again Exhibits Burst Mode Operation Ripple at 5mA Load,

LT1307B Does Not

series RC network connected between the V pin and

ground. Low-battery detector A4’s open collector output

(LBO) pulls low when the LBI pin voltage drops below

C

8

LT1307/ LT1307B

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APPLICATIONS INFORMATION

Trace B. Similarly, Figure 4 details the two circuits with a

load step from 5mA to 45mA with a 1.5V input.

quite evident, as is this particular device’s 575kHz switch-

ing frequency (nominal switching frequency is 600kHz).

Note,however,theabsenceofsignificantenergyat455kHz.

Figure7’s plotreduces thefrequencyspanfrom255kHzto

655kHz with a 455kHz center. Burst Mode low frequency

ripple creates sidebands around the 575kHz switching

fundamental. These sidebands have low signal amplitude

at 455kHz, measuring –55dBmV_RMS. As load current is

further reduced, the Burst Mode frequency decreases.

This spaces the sidebands around the switching fre-

quency closer together, moving spectral energy further

The LT1307B also can be used in lower current applica-

tions where a clean, low ripple output is needed. Figure 5

details transient response of a single cell to 3.3V con-

verter, using an inductor value of 100µH. This high induc-

tance minimizes ripple current, allowing the LT1307B to

regulate without skipping cycles. As the load current is

stepped from 5mA to 10mA, the output voltage responds

cleanly. Note that the V pin loop compensation has been

C

made more conservative (increased C, decreased R).

40

RBW = 100Hz

30

V

OUT

100mV/DIV

AC COUPLED

20

10

0

I_L

–10

–20

–30

–40

–50

–60

20mA/DIV

10mA

I_L

5mA

V

_IN= 1.25V

1ms/DIV

1307 F05

V_OUT= 3.3V

Figure 5. Increasing L to 100µH, Along with R_C= 36k,

C_C= 20nF and C_OUT= 10µF, Low Noise Performance of

LT1307B Can Be Realized at Light Loads of 5mA to 10mA

1

10

100

1000

FREQUENCY (kHz)

1307 F06

Figure 6. Spectral Noise Plot of 3.3V Converter Delivering

5mA Load. Burst Mode Fundamental at 5.1kHz is 23dBmV

At light loads, the LT1307B will begin to skip alternate

cycles. The load point at which this occurs can be de-

creasedbyincreasingtheinductorvalue. However, output

ripplewillcontinuetobesignificantlyless thantheLT1307

output ripple. Further, the LT1307B can be forced into

micropower mode, where I_Qfalls from 1mA to 50µA by

RMS

or 14mV

RMS

–20

–25

–30

–35

–40

–45

–50

–55

–60

–65

–70

RBW = 100Hz

pulling down V to 0.3V or less externally.

C

DC/DC CONVERTER NOISE CONSIDERATIONS

Switching regulator noise is a significant concern in many

communications systems. The LT1307 is designed to

keep noise energy out of the sensitive 455kHz band at all

load levels while consuming only 60µW to 100µW at no

load. At light load levels, the device is in Burst Mode,

causing low frequency ripple to appear at the output.

Figure 6 details spectral noise directly at the output of

Figure 1’s circuit in a 1kHz to 1MHz bandwidth. The

converter supplies a 5mA load from a 1.25V input. The

Burst Mode fundamental at 5.1kHz and its harmonics are

255

455

FREQUENCY (kHz)

655

1307 F07

Figure 7. Span Centered at 455kHz Shows –55dBmV

RMS

(1.8µV_RMS) at 455kHz. Burst Mode Creates Sidebands 5.1kHz

Apart Around the Switching Frequency Fundamental of 575kHz

9

LT1307/ LT1307B

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APPLICATIONS INFORMATION

away from 455kHz. Figure 8 shows the noise spectrum of To eliminate the low frequency noise of Figure 6, the

the converter with the load increased to 20mA. The

LT1307 can be replaced with the LT1307B. Figure 9

LT1307 shifts out of Burst Mode operation, eliminating details thespectralnoiseattheoutputofFigure1’s circuit

low frequency ripple. Spectral energy is present only at

the switching fundamental and its harmonics. Noise

usinganLT1307Bat5mAload. Althoughspectralenergy

is present at 333kHz due to alternate pulse skipping, all

Burst Mode operation spectral components are gone.

Alternate pulse skipping can be eliminated by increasing

voltage measures –5dBmV

or 560µV

at the

RMS

575kHzswitchingfrequency,andis below–60dBmV

RMS

for all other frequencies in the range. By combining Burst inductance.

Mode with fixed frequency operation, the LT1307 keeps

noise away from 455kHz.

FREQUENCY COMPENSATION

Obtaining proper values for the frequency compensation

network is largely an empirical, iterative procedure, since

variations in input and output voltage, topology, capacitor

value and ESR, and inductance make a simple formula

elusive. As an example, consider the case of a 1.25V to

3.3V boost converter supplying 50mA. To determine

optimum compensation, the circuit is built and a transient

load is applied to the circuit. Figure 10 shows the setup.

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

RBW = 100Hz

MBR0520L

10µH

V

OUT

255

455

FREQUENCY (kHz)

655

V

SW

FB

IN

66Ω

1M

1307 F08

SHDN

LT1307

1µF

Figure 8. With Converter Delivering 20mA, Low Frequency

Sidebands Disappear. Noise is Present Only at the 575kHz

Switching Frequency

V

C

3300Ω

10µF*

1.25V

GND

R

590k

C

50Ω

0

–10

–20

–30

–40

–50

–60

–70

–80

–90

–100

1307 • F10

*CERAMIC

Figure 10. Boost Converter with Simulated Load

Figure 11a details transient response without compensa-

tion components. Although the output ripple voltage at a

1mA load is low, allowing the error amplifier to operate

widebandresults inexcessiverippleata50mAload. Some

kind of loop stabilizing network is obviously required. A

100k/22nF series RC is connected to the V_Cpin, resulting

in the response pictured in Figure 11b. The output settles

in about 7ms to 8ms. This may be acceptable, but we can

do better. Reducing C to 2nF gives Figure 11c’s response.

This is clearly in the right direction. After another order of

magnitude reduction, Figure 11d’s response shows some

205

455

705

FREQUENCY (kHz)

LT1307 • F09

Figure 9. LT1307B at 5mA Load Shows No Audio Components

or Sidebands About Switching Frequency, 333kHz

Fundamental Amplitude is –10dBmV, or 316µV

RMS

10

LT1307/ LT1307B

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APPLICATIONS INFORMATION

V

OUT

V

OUT

200mV/DIV

AC COUPLED

200mV/DIV

AC COUPLED

51mA

I_L

51mA

I_L

1mA

5ms/DIV

1307 F11a

5ms/DIV

1307 F11b

Figure 11a. V Pin Left Unconnected. Output Ripple

Voltage is 300mV_P-PUnder Load

Figure 11b. Inclusion of a 100k/22nF Series RC on V_C

Pin Results in Overdamped Stable Response

C

V

OUT

V

OUT

200mV/DIV

AC COUPLED

200mV/DIV

AC COUPLED

51mA

I_L

51mA

I_L

1mA

1ms/DIV

1307 F11a

500µs/DIV

1307 F11b

Figure 11c. Reducing C to 2nF Speeds Up Response,

Although Still Overdamped

Figure 11d. A 100k/200pF Series RC Shows Some

Underdamping

V_OUT

200mV/DIV

AC COUPLED

51mA

I_L

1mA

1ms/DIV

1307 F11b

Figure 11e. A 100k/680pF RC Provides Optimum

Settling Time with No Ringing

underdamping.Nowsettlingtimeis about300µs.Increas-

pole, requiring added C at the V_Cpin network to prevent

ingCto680pFresults intheresponseshowninFigure11e.

This response has minimum settling time with no over-

shoot or underdamping.

loop oscillation.

Observant readers will notice R has been set to 100k for all

the photos in Figure 11. Usable R values can be found in

the 10k to 500k range, but after too many trips to the

resistor bins, 100k wins.

Converters using a 2-cell input need more capacitance at

the output. This added capacitance moves in the output

11

LT1307/ LT1307B

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APPLICATIONS INFORMATION

COMPONENT SELECTION

Inductors

LAYOUT HINTS

The LT1307 switches current at high speed, mandating

carefulattentiontolayoutforproperperformance.Youwill

not get advertised performance with careless layouts.

Figure 12 shows recommended component placement.

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

of the switching loops. Input capacitor C 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 to regulate or oscillation. A 1µF ceramic bypass

capacitor is the only input capacitance required provided

the battery has a low inductance path to the circuit. The

battery itself provides the bulk capacitance the device

requires forproperoperation.Ifthebatteryis locatedsome

distancefromthecircuit, anadditionalinputcapacitormay

berequired. A100µFaluminumelectrolyticunitworks well

in these cases. This capacitor need not have low ESR.

Inductors appropriate for use with the LT1307 must pos-

sess three attributes. First, they must have low core loss at

600kHz. Most ferrite core units have acceptable losses at

this switching frequency. Inexpensive iron powder cores

should be viewed suspiciously, as core losses can cause

significant efficiency penalties at 600kHz. Second, the

inductor must handle current of 500mA without saturat-

ing.This places alowerlimitonthephysicalsizeoftheunit.

Molded chokes or chip inductors usually do not have

enough core to support 500mA current and are unsuitable

for the application. Lastly, the inductor should have low

DCR (copper wire resistance) to prevent efficiency-killing

I²Rlosses.LinearTechnologyhas identifiedseveralinduc-

tors suitable for use with the LT1307. This is not an

exclusive list. There are many magnetics vendors whose

components are suitable for use. A few vendor’s compo-

nents are listed in Table 1.

IN

C

R

C

KEEP TRACES

OR LEADS SHORT!

LT1307

1

2

3

4

8

7

6

5

Table 1. Inductors Suitable for Use with the LT1307

MAX

HEIGHT

(mm)

R1 R2

PART

VALUE DCR

MFR

COMMENT

L

C

IN

LQH3C100

DO1608-103

CD43-100

CD54-100

10µH

0.57 Murata-Erie

2.0

3.0

3.2

4.5

2.2

Smallest Size

0.16

0.18

0.10

Coilcraft

Sumida

D

C

OUT

Best Efficiency

1210 Footprint

1306 F12

CTX32CT-100 10µH

0.50 Coiltronics

V

OUT

GROUND

Figure 12. Recommended Component Placement. Traces

Carrying High Current Are Direct. Trace Area at FB Pin and V

Capacitors

C

Pin is Kept Low. Lead Length to Battery Should Be Kept Short

For single cell applications, a 10µF ceramic output capaci-

tor is generally all that is required. Ripple voltage in Burst

Mode can be reduced by increasing output capacitance.

For 2- and 3-cell applications, more than 10µF is needed.

For a typical 2-cell to 5V application, a 47µF to 100µF low

ESRtantalumcapacitorworks well.AVXTPSseries (100%

surgetested)orSprague(don’tbevague—askforSprague)

594Dseries arebothgoodchoices forlowESRcapacitors.

Alternatively, a 10µF ceramic in parallel with a low cost

(read high ESR) electrolytic capacitor, either tantalum or

aluminum, can be used instead. For through hole applica-

OPERATION FROM A LABORATORY POWER SUPPLY

If a lab supply is used, the leads used to connect the circuit

to the supply can have significant inductance at the

LT1307’s switching frequency. As in the previous situa-

tion, anelectrolyticcapacitormayberequiredatthecircuit

in order to reduce the AC impedance of the input suffi-

ciently. An alternative solution would be to attach the

circuitdirectlytothepowersupplyatthesupplyterminals,

without the use of leads. The power supply’s output

capacitance will then provide the bulk capacitance the

LT1307 circuit requires.

12

LT1307/ LT1307B

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APPLICATIONS INFORMATION

V

tions wheresmallsizeis notcritical, PanasonicHFQseries

aluminum electrolytic capacitors have been found to per-

form well.

IN

Q3

R2

400k

SHUTDOWN

CURRENT

SHDN

Table 2. Vendor Telephone Numbers

200k

VENDOR

Coilcraft

Marcon

Murata-Erie

Sumida

Tokin

COMPONENTS

Inductors

TELEPHONE

(708) 639-6400

(708) 913-9980

(404) 436-1300

(847) 956-0666

(408) 432-8020

(207) 282-5111

(603) 224-1961

(407) 241-7876

START-UP

CURRENT

Capacitors

Q2

Q1

Inductors, Capacitors

Inductors

1307 F13

Capacitors

Figure 13. Shutdown Circuit

AVX

Capacitors

Sprague

Coiltronics

Capacitors

LOW-BATTERY DETECTOR

Inductors

The LT1307’s low-battery detector is a simple PNP input

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

tive input of the gain stage is tied internally to a 200mV

±5% reference. The positive input is the LBI pin. Arrange-

ment as a low-battery detector is straightforward. Figure

14 details 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 refer-

ence can also be accessed as shown in Figure 15.

Diodes

Most of the application circuits on this data sheet specify

the Motorola MBR0520L surface mount Schottky diode.

This 0.5A, low drop diode complements the LT1307 quite

well. In lower current applications, a 1N4148 can be used,

although efficiency will suffer due to the higher forward

drop. This effect is particularly noticeable at low output

voltages. For higher voltage output applications, such as

LCD bias generators, the extra drop is a small percentage

of the output voltage so the efficiency penalty is small. The

low cost of the 1N4148 makes it attractive wherever it can

be used. In through hole applications the 1N5818 is the all

around best choice.

3.3V

R1

V

IN

LT1307

LBO

1M

LBI

+

–

TO PROCESSOR

R2

100k

200mV

INTERNAL

REFERENCE

V

LB

– 200mV

R1 =

SHUTDOWN PIN

2µA

GND

The LT1307 has a Shutdown pin (SHDN) that must be

groundedtoshutthedevicedownortiedtoavoltageequal

1307 F14

or greater than V to operate. The shutdown circuit is

shown in Figure 13.

IN

Figure 14. Setting Low-Battery Detector Trip Point

Note that allowing SHDN to float turns on both the start-

up current (Q2) and the shutdown current (Q3) for V >

200k

IN

V

IN

2V .TheLT1307doesn’tknowwhattodointhis situation

2N3906

LBO

LBI

BE

LT1307

and behaves erratically. SHDN voltage above V is al-

IN

V

REF

200mV

+

lowed. This merely reverse-biases Q3’s base emitter junc-

tion, a benign condition.

GND

10k

10µF

1307 F15

Figure 15. Accessing 200mV Reference

13

LT1307/ LT1307B

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APPLICATIONS INFORMATION

REVERSE BATTERY CONSIDERATIONS

tion after sustaining polarity reversal for the life of a single

AA alkaline cell.

The LT1307 is built ona junction-isolatedbipolar process.

The p-type substrate is connected to the GND pin of the

LT1307. Substrate diodes, normally reverse-biased, are

When using a 2- or 3-cell supply, an external protection

diode is recommended as shown in Figure 18. When the

batterypolarityis reversed, the1N4001conducts, limiting

reverse voltage across the LT1307 to a single diode drop.

This arrangementwillquicklydepletethecells’energy,but

it does prevent the LT1307 from excessive power dissipa-

tion and potential damage.

present on the SW pin and the V pin as shown in Figure

IN

16. When the battery polarity is reversed, these diodes

conduct, as illustrated in Figure 17. With a single AA or

AAA cell, several hundred milliamperes flow in the circuit.

TheLT1307canwithstandthis currentwithoutdamage.In

laboratory tests, the LT1307 performed without degrada-

–1.5V

CURRENT

FLOW

1.5V

V

IN

SW

V

IN

SW

1 CELL

D1

D2

Q1

1 CELL

D1

D2

Q1

LT1307

GND

LT1307

GND

1307 F17

1307 F16

Figure 17. When Cell Is Reversed Current Flows through

D1 and D2

Figure 16. LT1307 Showing Internal Substrate Diodes D1 and D2.

In Normal Operation Diodes are Reverse-Biased

V

IN

SW

2 OR 3

1N4001

CELLS

LT1307

GND

1307 F18

Figure 18. 1N4001 Diode Protects LT1307 from Excessive Power

Dissipation When a 2- or 3-Cell Battery is Used

14

LT1307/ LT1307B

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TYPICAL APPLICATIONS N

Externally Controlled Burst Mode Operation

L1

10µH

MBR0520

V

OUT

1µF

CERAMIC

R4

1M

300k

V

SW

IN

V

C

FB

100k

R5

590k

2

LT1307B

R3

698k

CELLS

V

3.3V

OUT

M1

LBO

LBI

2N7002

200mA

SHDN

GND

C2*

10µF

CERAMIC

3.0V IN LOW-POWER

Burst Mode OPERATION

C1 = AVX TPSC107K006R0150

L1 = COILCRAFT DO1608-103

SUMIDA CD43-100

1nF

+

R2

499k

C1

R1

100µF

10M

* C2 OPTIONAL: REDUCES OUTPUT

RIPPLE CAUSED BY C1'S ESR

GROUND = HIGH POWER/LOW NOISE

FLOAT = Burst Mode OPERATION

1307 F19

SHUTDOWN

detector now drives the V pin. R3 and R2 set the output

This circuit overcomes the limitation of load-based

transitioning between Burst Mode operation and constant

switching mode by adding external control. If M1’s gate is

grounded by an external open-drain signal, the converter

functions normallyinconstantswitchingmode,delivering

3.3V. Output noise is low, however efficiency at loads less

than 1mA is poor due to the 1mA supply current of the

LT1307B. If M1’s gate is allowed to float, the low-battery

C

to 3V by allowing M1’s gate to go to V_OUTuntil the output

voltage drops below 3V. R1 adds hysteresis, resulting in

low-frequency Burst Mode operation ripple voltage at the

output. By pulling the V_Cpin below a V , quiescent

BE

currentoftheLT1307Bdrops to60µA, resultinginaccept-

able efficiency at loads in the 100µA range.

V

OUT

V

OUT

500mV/DIV

100mV/DIV

100mA

I_L

10mA

I_L

100µA

10mA

0.2s/DIV

1307 F20

2ms/DIV

1307 F21

This photo details output voltage as the circuit is switched

between the two modes. Load current is 100µA in Burst

Mode operation; 10mA in constant switching mode.

This photo shows transient response in constant switch-

ing mode with a 10mA to 100mA stepped load. Output

ripple at the switching frequency can be reduced consid-

erably by adding a 10µF ceramic capacitor in parallel with

the 100µF tantalum.

15

LT1307/ LT1307B

TYPICAL APPLICATIONS N

U

Low Cost 2-Cell to 5V

L1

V

IN

1N5818

10µH

1.4V TO 3.3V

5V

100mA

C1*

220µF

6.3V

C2

220µF

6.3V

+

V

SW

FB

IN

LT1307

SHDN

1M

0.1µF

GND

100k

4700pF

323k

1307 TA02

C1, C2: PANASONIC ECA0JFQ221

(DIGI-KEY P5604-ND)

L1: SUMIDA CD43-100

Step-Up/Step-Down Converter

2.2µF

CERAMIC

L1

10µH

V

IN

MBR0520

2.1V TO 4.8V

•

3.3V

100mA

V

IN

SW

10µF

1µF

CERAMIC

LT1307

1.02M

608k

•

3

CELLS

V

FB

GND

C

L1*

SHDN

100k

1000pF

SHDN

1307 TA03

L1: COILTRONICS CTX10-1 OR 2 MURATA ERIE LQH3C100

EFFICIENCY ≈70% TO 73%

Constant Current NiCd Battery Charger with Overvoltage Protection

for Acknowledge-Back Pagers

2.2µF

CERAMIC

L1

10µH

V

IN

MBR0520L

15mA

1.8V TO 1V

3

2

•

1µF

V

SW

FB

IN

1M

•

1

V

C

1µF

CERAMIC

OVERVOLTAGE

PROTECTION

323k

1 CELL

AA OR

AAA

3 CELLS

NiCd

LT1307

4

30k

200mV

1nF

–100mV

LBO

LBI

SHDN

GND

47k

2200pF

280k

6.7Ω

1 = CHARGE

0 = SHUTDOWN

3V

1307 TA04

L1: COILTRONICS CTX10-1

16

LT1307/ LT1307B

U

TYPICAL APPLICATIONS N

Single Cell Powered Constant Current LED Driver

L1

D1

10µH

V

IN

100k

D2

V

SW

FB

IN

Q1

2N3906

LBO

NC

LT1307B

C1

1µF

CERAMIC

AA

CELL

V

C

LBI

SHDN

GND

+

C2

1µF

40mA

C3

22µF

CERAMIC

R2

22k

R1

5.1Ω

100k

1307 TA05

ON/OFF

L1: MURATA-ERIE LQH3C100K04

D1: 1N4148

C1, C2: CERAMIC

V

IN

D2, D3: LUMEX SSL-X100133SRC/4 "MEGA-BRITE" RED LED

OR PANASONIC LNG992CF9 HIGH BRIGHTNESS BLUE LED

Flash Memory VPP Supply

L1

10µH

D1

12V/30mA FROM 3V

12V/60mA FROM 5V

V

IN

3V TO 5.5V

+

~250mV RIPPLE

0.33µF

1µF

P-P

TANTALUM

10pF

V

SW

FB

IN

SHUTDOWN

SHDN

LT1307

0.33µF

CERAMIC

×2

2M

1%

1N4148

47k

V

C

GND

232k

1%

2000pF

D1: MOTOROLA MBR0520L

L1: MURATA-ERIE LQH3C100K04

1307 TA09

High Voltage Flyback Converter

OPTIONAL

DOUBLER

2V

OUT

0.01µF

0.1µF

T1

1:12

1N4148

V

IN

T1: DALE LPE3325-A190, n = 12 (605) 665-9301

R1

1V TO 5V

•

1µF

CERAMIC

3

1

4

6

V

OUT

= 1.22V 1 +

(

)

R2

MAXIMUM DUTY CYCLE: ≈80%

•

DC

1 – DC

FOR FLYBACK, V

=

n(V – V

)

SW

OUT

IN

V

SW

FB

IN

R1

0.8

FOR 1V , MAXIMUM V

=

OUT

12(1 – 0.2) ≈ 37V

IN

SHUTDOWN

SHDN

LT1307

V

OUT

1 – 0.8

≈ 85V.

OUT

FOR 2V , MAXIMUM V

IN

HIGHER VOLTAGES ACHIEVED WITH CAPACITIVE DOUBLER OR TRIPLER

V

C

R2

240k

1%

NO SNUBBER REQUIRED WITH SPECIFIED TRANSFORMER AND V < 5V

IN

GND

0.1µF

100k

1000pF

1307 TA06

17

LT1307/ LT1307B

TYPICAL APPLICATIONS N

U

Single Cell CCFL Power Supply

6

3

10

1

47pF

3kV

T1

4

5

2

1.5V

100Ω

C1

0.1µF

CCFL

Q1

Q2

1.5V

L1

33µH

D1

1.5V

V

IN

SW

LT1307B

1N4148

1µF

CERAMIC

10k

1

SHDN

GND

FB

CELL

1N4148

V

C

1k

0.1µF

10k

DIMMING

1307 TA08

1 = OPERATE

0 = SHUTDOWN

C1: WIMA MKP-20

D1: MOTOROLA MBR0520L

L1: SUMIDA CD54-330

T1: COILTRONICS CTX110611

Q1, Q2: ZETEX FZT-849

U

PACKAGE DESCRIPTION ^{Dimensions in inches (millimeters) unless otherwise noted.}

MS8 Package

8-Lead Plastic MSOP

(LTC DWG # 05-08-1660)

0.118 ± 0.004*

0.040 ± 0.006

(1.02 ± 0.15)

0.006 ± 0.004

(0.15 ± 0.10)

(3.00 ± 0.10)

8

7

6

5

0.007

(0.18)

0° – 6° TYP

SEATING

PLANE

0.012

(0.30)

0.118 ± 0.004**

(3.00 ± 0.10)

0.192 ± 0.004

(4.88 ± 0.10)

0.021 ± 0.004

(0.53 ± 0.01)

0.025

(0.65)

TYP

*

DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH,

PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

1

2

3

4

** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS.

MSOP08 0596

INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

18

LT1307/ LT1307B

U

PACKAGE DESCRIPTION ^{Dimensions in inches (millimeters) unless otherwise noted.}

N8 Package

8-Lead PDIP (Narrow 0.300)

(LTC DWG # 05-08-1510)

0.400*

0.130 ± 0.005

0.300 – 0.325

0.045 – 0.065

(1.143 – 1.651)

(10.160)

MAX

(3.302 ± 0.127)

(7.620 – 8.255)

8

7

6

5

0.065

(1.651)

TYP

0.009 – 0.015

0.255 ± 0.015*

(6.477 ± 0.381)

0.125

(0.229 – 0.381)

0.005

0.015

(3.175)

MIN

(0.127)

MIN

+0.025

–0.015

(0.380)

MIN

0.325

+0.635

–0.381

1

2

4

3

8.255

(

)

0.100 ± 0.010

0.018 ± 0.003

(2.540 ± 0.254)

(0.457 ± 0.076)

N8 0695

*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)

S8 Package

8-Lead Plastic Small Outline (Narrow 0.150)

(LTC DWG # 05-08-1610)

0.189 – 0.197*

(4.801 – 5.004)

7

5

8

6

0.150 – 0.157**

(3.810 – 3.988)

0.228 – 0.244

(5.791 – 6.197)

1

3

4

2

0.010 – 0.020

(0.254 – 0.508)

× 45°

0.053 – 0.069

(1.346 – 1.752)

0.004 – 0.010

(0.101 – 0.254)

0.008 – 0.010

(0.203 – 0.254)

0°– 8° TYP

0.016 – 0.050

0.406 – 1.270

0.050

(1.270)

BSC

0.014 – 0.019

(0.355 – 0.483)

*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH

SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

SO8 0695

**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD

FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

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 represen-

tationthattheinterconnectionofits circuits as describedhereinwillnotinfringeonexistingpatentrights.

19

LT1307/ LT1307B

U

TYPICAL APPLICATION

LCD Bias Generator

D1

–V

OUT

0.1µF

1µF

D2

D3

L1

V

OUT

16V TO 24V

5mA FROM 1 CELL

15mA FROM 2 CELLS

35mA FROM 3 CELLS

V

IN

SW

1µF

10pF

LT1307

3.3M

1, 2 OR 3

CELLS

V

C1

FB

C

SHDN

GND

100k

4700pF

1M

215k

1307 TA07

3.3µF

SHUTDOWN

+

L1: 3.3µH (1 CELL)

4.µ7H (2 CELLS)

1µ0H (3 CELLS)

SUMIDA CD43

100k

MURATA-ERIE LQH3C

COILCRAFT D01608

PWM IN 3.3V, 0% TO 100%

C1: µ1F FOR +OUTPUT

0.0µ1F FOR –OUTPUT

D1 TO D3: MBR0530 OR 1N4148

RELATED PARTS

PART NUMBER

LTC^®1163

LTC1174

DESCRIPTION

COMMENTS

Triple High Side Driver for 2-Cell Inputs

1.8V Minimum Input, Drives N-Channel MOSFETs

94% Efficiency, 130µA I , 9V to 5V at 300mA

Micropower Step-Down DC/DC Converter

High Output Current Micropower DC/DC Converter

2-Cell Micropower DC/DC Converter

Q

LT1302

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

Q

LT1304

Low-Battery Detector Active in Shutdown

2.8µA I , Adjustable Hysteresis

LTC1440/1/2

LTC1516

Ultralow Power Single/Dual Comparators with Reference

2-Cell to 5V Regulated Charge Pump

Q

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

Q

LT1521

Micropower Low Dropout Linear Regulator

500mV Dropout, 300mA Current, 12µA I

Q

LT/GP 1196 7K • PRINTED IN THE USA

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

20

●

(408) 432-1900 FAX: (408) 434-0507 TELEX: 499-3977

LINEAR TECHNOLOGY CORPORATION 1995


型号：	LT1307CS8#TRPBF
厂家：	Linear
描述：	LT1307 - Single Cell Micropower 600kHz PWM DC/DC Converters; Package: SO; Pins: 8; Temperature Range: 0°C to 70°C 转换器
文件：	总20页 (文件大小：380K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LT1307CS8#TRPBF [Linear]

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