LT1934IS6-1#TRM_技术文档

LT1934/LT1934-1

Micropower Step-Down

Switching Regulators

in ThinSOT and DFN

FEATURES

DESCRIPTION

TheLT^®1934isamicropowerstep-downDC/DCconverter

with internal 400mA power switch, packaged in a low

proﬁle (1mm) ThinSOT. With its wide input range of 3.2V

to 34V, the LT1934 can regulate a wide variety of power

sources, from 4-cell alkaline batteries and 5V logic rails

to unregulated wall transformers and lead-acid batteries.

Quiescent current is just 12μA and a zero current shut-

down mode disconnects the load from the input source,

simplifying power management in battery-powered sys-

tems. Burst Mode^®operation and the low drop internal

power switch result in high efﬁciency over a broad range

of load current.

n

Wide Input Voltage Range: 3.2V to 34V

Micropower Operation: I = 12μA

n

Q

n

5V at 250mA from 6.5V to 34V Input (LT1934)

5V at 60mA from 6.5V to 34V Input (LT1934-1)

3.3V at 250mA from 4.5V to 34V Input (LT1934)

3.3V at 60mA from 4.5V to 34V Input (LT1934-1)

Low Shutdown Current: <1μA

Low V

Switch: 200mV at 300mA

CESAT

Low Proﬁle (1mm) SOT-23 (ThinSOT™) and

(2mm × 3mm × 0.8mm) 6-Pin DFN Package

APPLICATIONS

The LT1934 provides up to 300mA of output current. The

LT1934-1 has a lower current limit, allowing optimum

choice of external components when the required output

current is less than 60mA. Fast current limiting protects

the LT1934 and external components against shorted

outputs, even at 34V input.

n

Wall Transformer Regulation

n

Automotive Battery Regulation

n

Standby Power for Portable Products

Distributed Supply Regulation

Industrial Control Supplies

n

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

Burst Mode is a registered trademark of Linear Technology Corporation.

ThinSOT is a trademark of Linear Technology Corporation.

All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

3.3V Step-Down Converter

Efﬁciency

100

D2

LT1934

IN

V

= 12V

90

80

70

60

50

0.22μF

BOOST

L1

V

= 5V

47μH

OUT

V

OUT

V

IN

V

IN

SW

3.3V

4.5V TO 34V

250mA

C2

2.2μF

V

OUT

= 3.3V

D1

LT1934

10pF

1M

+

C1

100μF

ON OFF

SHDN

GND

FB

604k

C1: SANYO 4TPB100M

1934 TA01

0.1

1

10

100

C2: TAIYO YUDEN GMK325BJ225MN

D1: ON SEMICONDUCTOR MBR0540

D2: CENTRAL CMDSH-3

LOAD CURRENT (mA)

1934 TA02

L1: SUMIDA CDRH4D28-470

1934fe

1

LT1934/LT1934-1

(Note 1)

ABSOLUTE MAXIMUM RATINGS

Input Voltage (V )................................................... 34V

Operating Temperature Range (Note 2)

IN

BOOST Pin Voltage ................................................. 40V

BOOST Pin Above SW Pin........................................ 20V

SHDN Pin................................................................. 34V

FB Voltage.................................................................. 6V

LT1934E/LT1934E-1.............................–40°C to 85°C

LT1934I/LT1934I-1.............................–40°C to 125°C

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

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

Lead Temperature (Soldering, 10 sec)

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

IN

TSOT-23............................................................ 300°C

PIN CONFIGURATION

TOP VIEW

6

5

4

FB

BOOST

SW

1

2

3

BOOST 1

GND 2

FB 3

6 SW

5 V

7

GND

SHDN

IN

V

IN

4 SHDN

S6 PACKAGE

6-LEAD PLASTIC TSOT-23

= 125°C, θ = 250°C/ W, θ = 102°C/W

DCB PACKAGE

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

T

JMAX

JA

JC

θ

= 73.5°C/ W, θ = 12°C/W

JC

EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDEDED TO PCB

JA

ORDER INFORMATION

LEAD FREE FINISH

LT1934ES6#PBF

LT1934ES6-1#PBF

LT1934IS6#PBF

LT1934IS6-1#PBF

LT1934IDCB#PBF

LT1934EDCB#PBF

LT1934IDCB-1#PBF

LT1934EDCB-1#PBF

LEAD BASED FINISH

LT1934ES6

TAPE AND REEL

S6 PART MARKING*

PACKAGE DESCRIPTION

TEMPERATURE RANGE

LT1934ES6#TRPBF

LT1934ES6-1#TRPBF

LT1934IS6#TRPBF

LT1934IS6-1#TRPBF

LT1934IDCB#TRPBF

LT1934EDCB#TRPBF

LT1934IDCB-1#TRPBF

LT1934EDCB-1#TRPBF

TAPE AND REEL

LTXP

6-Lead Plastic TSOT-23

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

TEMPERATURE RANGE

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

–40°C to 125°C

–40°C to 85°C

LTF8

6-Lead Plastic TSOT-23

LTAJB

LTAJC

LCFZ

6-Lead Plastic TSOT-23

6-Lead (2mm × 3mm) Plastic DFN

PACKAGE DESCRIPTION

LCFZ

LDHC

S6 PART MARKING*

LTXP

LT1934ES6#TR

6-Lead Plastic TSOT-23

LT1934ES6-1

LT1934ES6-1#TR

LT1934IS6#TR

LTF8

6-Lead Plastic TSOT-23

LT1934IS6

LTAJB

LTAJC

LCFZ

6-Lead Plastic TSOT-23

LT1934IS6-1

LT1934IS6-1#TR

6-Lead Plastic TSOT-23

LT1934IDCB

LT1934IDCB#TR

6-Lead (2mm × 3mm) Plastic DFN

LT1934EDCB

LT1934EDCB#TR

LT1934IDCB-1#TR

LT1934EDCB-1#TR

LCFZ

LT1934IDCB-1

LDHC

LT1934EDCB-1

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/

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

1934fe

2

LT1934/LT1934-1

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

temperature range, otherwise speciﬁcations are at T_A= 25°C. V_IN= 10V, V_BOOST= 15V, unless otherwise noted.

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Undervoltage Lockout

3

3.2

3.6

V

l

–40°C ≤ T ≤ 85°C

A

–40°C ≤ T ≤ 125°C

A

Quiescent Current

V

FB

= 1.3V

12

22

26

μA

l

–40°C ≤ T ≤ 85°C

A

–40°C ≤ T ≤ 125°C

A

V

= 0V

0.01

2

μA

SHDN

l

FB Comparator Trip Voltage

Falling

–40°C ≤ T ≤ 85°C

1.22

1.21

1.25

1.27

V

FB

A

–40°C ≤ T ≤ 125°C

A

FB Comparator Hysteresis

FB Pin Bias Current

10

mV

l

V

FB

= 1.25V

–40°C ≤ T ≤ 85°C

2

15

60

nA

A

–40°C ≤ T ≤ 125°C

A

FB Voltage Line Regulation

Switch Off Time

4V < V < 34V

0.007

%/V

IN

V

FB

V

FB

> 1V

= 0V

1.4

1.8

12

2.3

μs

l

Maximum Duty Cycle

V

FB

= 1V

–40°C ≤ T ≤ 85°C

85

83

88

%

A

–40°C ≤ T ≤ 125°C

A

Switch V

I

SW

I

SW

I

SW

I

SW

= 300mA (LT1934, S6 Package)

= 300mA (LT1934, DCB Package)

= 75mA (LT1934-1, S6 Package)

= 75mA (LT1934-1, DCB Package)

200

225

65

300

120

mV

CESAT

70

Switch Current Limit

LT1934

LT1934-1

350

90

400

120

490

160

mA

BOOST Pin Current

I

SW

I

SW

= 300mA (LT1934)

= 75mA (LT1934-1)

8.5

6.0

12

10

mA

Minimum Boost Voltage (Note 3)

I

SW

I

SW

= 300mA (LT1934)

= 75mA (LT1934-1)

1.8

1.7

2.5

V

Switch Leakage Current

2

μA

SHDN Pin Current

V

SHDN

V

SHDN

= 2.3V

= 34V

0.5

1.5

μA

5

SHDN Input Voltage High

SHDN Input Voltage Low

2.3

V

0.25

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.

operating temperature range are assured by design, characterization and

correlation with statistical process controls. The LT1934I and LT1934I-1

speciﬁcations are guaranteed over the –40°C to 125°C temperature range.

Note 3: This is the minimum voltage across the boost capacitor needed to

Note 2: The LT1934E and LT1934E-1 are guaranteed to meet performance

guarantee full saturation of the internal power switch.

speciﬁcations from 0°C to 85°C. Speciﬁcations over the –40°C to 85°C

1934fe

3

LT1934/LT1934-1

TYPICAL PERFORMANCE CHARACTERISTICS

LT1934 Efﬁciency, V_OUT= 5V

LT1934 Efﬁciency, V_OUT= 3.3V

LT1934-1 Efﬁciency, V_OUT= 5V

100

90

80

70

60

50

100

90

80

70

60

50

100

90

80

70

60

50

LT1934

LT1934-1

V

= 5V

V

= 3.3V

V

= 5V

OUT

L = 47μH

= 25°C

L = 47μH

T = 25°C

A

L = 150μH

= 25°C

T

A

V

IN

= 5V

V

IN

= 12V

V

= 12V

= 24V

IN

V

IN

= 24V

V

IN

= 24V

IN

V

IN

= 12V

0.1

1

10

100

0.1

1

10

100

0.1

1

10

100

LOAD CURRENT (mA)

1934 G01

1934 G02

1934 G03

LT1934-1 Efﬁciency, V_OUT= 3.3V

Current Limit vs Temperature

Off Time vs Temperature

500

400

300

200

100

0

3.0

2.5

2.0

1.5

100

90

80

70

60

50

LT1934-1

LT1934

V

= 3.3V

OUT

L = 100μH

= 25°C

T

A

V

IN

= 12V

V

IN

= 24V

1.0

0.5

0

LT1934-1

50

TEMPERATURE (°C)

100 125

50

75 100 125

–50 –25

0

25

75

0.1

1

10

100

–50 –25

0

25

TEMPERATURE (°C)

LOAD CURRENT (mA)

1934 G06

1934 G04

1934 G05

SHDN Bias Current

vs SHDN Voltage

Frequency Foldback

V_FBvs Temperature

1.27

1.26

1.25

1.24

1.23

1.22

2.0

1.5

1.0

0.5

16

14

12

10

T

= 25°C

T

= 25oC

A

8

6

4

2

0

0.2

0.4

0.8

–50 –25

0

25

50

75 100 125

0

2

4

6

8

10

12

0

1.0

1.2

0.6

SHDN PIN VOLTAGE (V)

TEMPERATURE (°C)

FEEDBACK PIN VOLTAGE (V)

1934 G07

1934 G08

1934 G09

1934fe

4

LT1934/LT1934-1

TYPICAL PERFORMANCE CHARACTERISTICS

Quiescent Current

vs Temperature

Undervoltage Lockout

vs Temperature

20

15

10

5

4.0

3.5

3.0

2.5

0

2.0

–50 –25

0

25

50

75 100 125

–50 –25

0

25

50

75 100 125

TEMPERATURE (°C)

1934 G10

1934 G11

Minimum Input Voltage

V_OUT= 3.3V

Minimum Input Voltage

V_OUT= 5V

6.0

5.5

5.0

4.5

4.0

3.5

3.0

8

7

6

5

4

LT1934

V

T

= 3.3V

V

T

= 5V

OUT

A

OUT

A

= 25°C

BOOST DIODE TIED TO OUTPUT

V

IN

TO START

V

IN

TO START

V

IN

TO RUN

V

IN

TO RUN

0.1

1

10

100

0.1

1

10

100

LOAD CURRENT (mA)

1934 G12

1934 G13

PIN FUNCTIONS ^{(TSOT-23/DFN)}

BOOST (Pin 1/Pin 1): The BOOST pin is used to provide a inshutdownmode.TietogroundtoshutdowntheLT1934.

drive voltage, higher than the input voltage, to the internal Apply 2.3V or more for normal operation. If the shutdown

bipolar NPN power switch.

feature is not used, tie this pin to the V pin.

IN

GND (Pin 2/Pin 5): Tie the GND pin to a local ground plane VIN (Pin 5/Pin 3): The V pin supplies current to the

IN

below the LT1934 and the circuit components. Return the LT1934’s internal regulator and to the internal power

feedback divider to this pin.

switch. This pin must be locally bypassed.

FB (Pin 3/Pin 6): The LT1934 regulates its feedback pin SW (Pin 6/Pin 2): The SW pin is the output of the internal

to 1.25V. Connect the feedback resistor divider tap to this powerswitch.Connectthispintotheinductor,catchdiode

pin. Set the output voltage according to V

= 1.25V and boost capacitor.

OUT

(1 + R1/R2) or R1 = R2 (V /1.25 – 1).

OUT

Exposed Pad (Pin 7, DFN Package): This pin must be

SHDN(Pin4/Pin4):TheSHDNpinisusedtoputtheLT1934 soldered to ground plane.

1934fe

5

LT1934/LT1934-1

BLOCK DIAGRAM

V

IN

V

IN

+

C2

+

–

D2

BOOST

SW

ON TIME

R

S

Qa

C3

D1

12μs DELAY

Q

L1

OFF TIME

V

OUT

1.8μs DELAY

C1

SHDN

ON OFF

V

REF

1.25V

+

–

ENABLE

FEEDBACK

COMPARATOR

GND

FB

R1

R2

1934 BD

1934fe

6

LT1934/LT1934-1

(Refer to Block Diagram)

OPERATION

The LT1934 uses Burst Mode control, combining both low

quiescentcurrentoperationandhighswitchingfrequency,

which result in high efﬁciency across a wide range of load

currents and a small total circuit size.

ﬂip-ﬂop when this current reaches 400mA (120mA for

the LT1934-1). After the 1.8μs delay of the off-time one-

shot, the cycle repeats. Generally, the LT1934 will reach

current limit on every cycle—the off time is ﬁxed and

the on time is regulated so that the LT1934 operates at

the correct duty cycle. The 1.8μs off time is lengthened

when the FB pin voltage falls below 0.8V; this foldback

behavior helps control the output current during start-up

and overload. Figure 1 shows several waveforms of an

LT1934producing3.3Vfroma10Vinput.Whentheswitch

is on, the SW pin voltage is at 10V. When the switch is

off, the inductor current pulls the SW pin down until it is

clamped near ground by the external catch diode.

A comparator monitors the voltage at the FB pin of the

LT1934. If this voltage is higher than the internal 1.25V

reference,thecomparatordisablestheoscillatorandpower

switch. In this state, only the comparator, reference and

undervoltagelockoutcircuitsareactive,andthecurrentinto

the V pin is just 12μA. As the load current discharges the

IN

outputcapacitor,thevoltageattheFBpinfallsbelow1.25V

and the comparator enables the oscillator. The LT1934

begins to switch, delivering current to the output capaci-

tor. The output voltage rises, and when it overcomes the

feedbackcomparator’shysteresis,theoscillatorisdisabled

and the LT1934 returns to its micropower state.

The switch driver operates from either the input or from

the BOOST pin. An external capacitor and diode are used

to generate a voltage at the BOOST pin that is higher than

the input supply. This allows the driver to fully saturate

the bipolar switch for efﬁcient operation.

The oscillator consists of two one-shots and a ﬂip-ﬂop.

Arisingedgefromtheoff-timeone-shotsetstheﬂip-ﬂop,

whichturnsontheinternalNPNpowerswitch.Theswitch

remains on until either the on-time one-shot trips or the

current limit is reached. A sense resistor and ampliﬁer

monitor the current through the switch and resets the

If the SHDN pin is grounded, all internal circuits are turned

off and V current reduces to the device leakage current,

IN

typically a few nA.

V

OUT

50mV/DIV

V

SW

10V/DIV

I

SW

0.5A/DIV

I

LI

0.5A/DIV

1934 F01a

5μs/DIV

Figure 1. Operating Waveforms of the LT1934 Converting

10V to 3.3V at 180mA (Front Page Schematic)

1934fe

7

LT1934/LT1934-1

APPLICATIONS INFORMATION

Which One to Use: LT1934 or LT1934-1?

The duty cycle is the fraction of time that the internal

switch is on and is determined by the input and output

voltages:

The only difference between the LT1934 and LT1934-1

is the peak current through the internal switch and the

inductor. Ifyourmaximumloadcurrentislessthan60mA,

use the LT1934-1. If your maximum load is higher, use

the LT1934; it can supply up to ~300mA.

DC = (V

+ V )/(V – V + V )

D IN SW D

OUT

where V is the forward voltage drop of the catch diode

D

(~0.4V) and V is the voltage drop of the internal switch

SW

While the LT1934-1 can’t deliver as much output current,

it has other advantages. The lower peak switch current

allows the use of smaller components (input capacitor,

inductor and output capacitor). The ripple current at the

input of the LT1934-1 circuit will be smaller and may be

an important consideration if the input supply is current

limited or has high impedance. The LT1934-1’s current

draw during faults (output overload or short) and start-

up is lower.

(~0.3V at maximum load for the LT1934, ~0.1V for the

LT1934-1). This leads to a minimum input voltage of:

V

= (V

+ V )/DC

– V + V

MAX D SW

IN(MIN)

OUT

D

with DC

= 0.85.

MAX

Inductor Selection

A good ﬁrst choice for the inductor value is:

L = 2.5 • (V + V ) • 1.8μs/I

OUT

D

LIM

The maximum load current that the LT1934 or LT1934-1

can deliver depends on the value of the inductor used.

Table 1 lists inductor value, minimum output capacitor

and maximum load for 3.3V and 5V circuits. Increasing

the value of the capacitor will lower the output voltage

ripple. Component selection is covered in more detail in

the following sections.

where I

is the switch current limit (400mA for the

LIM

LT1934and120mAfortheLT1934-1).Thischoiceprovides

a worst-case maximum load current of 250mA (60mA for

the LT1934-1). The inductor’s RMS current rating must

be greater than the load current and its saturation current

should be greater than I . To keep efﬁciency high, the

LIM

series resistance (DCR) should be less than 0.3Ω (1Ω

for the LT1934-1). Table 2 lists several vendors and types

that are suitable.

Minimum Input Voltage

The minimum input voltage required to generate a par-

ticular output voltage is determined by either the LT1934’s

undervoltagelockoutof~3Vorbyitsmaximumdutycycle.

This simple rule may not provide the optimum value for

your application. If the load current is less, then you can

relax the value of the inductor and operate with higher

ripple current. This allows you to use a physically smaller

inductor, or one with a lower DCR resulting in higher

efﬁciency. The following provides more details to guide

inductor selection. First, the value must be chosen so that

the LT1934 can supply the maximum load current drawn

from the output. Second, the inductor must be rated ap-

propriately so that the LT1934 will function reliably and

the inductor itself will not be overly stressed.

Table 1

MINIMUM

MAXIMUM

LOAD

PART

V

L

C

OUT

LT1934

3.3V

100μH

47μH

33μH

100μH

47μH

33μH

300mA

250mA

200mA

5V

150μH

68μH

47μH

33μH

22μH

300mA

250mA

200mA

LT1934-1

3.3V

5V

150μH

100μH

68μH

15μH

10μH

60mA

45mA

20mA

Detailed Inductor Selection and

Maximum Load Current

220μH

150μH

100μH

10μH

4.7μH

60mA

45mA

20mA

The square wave that the LT1934 produces at its switch

pinresultsinatrianglewaveofcurrentintheinductor. The

LT1934 limits the peak inductor current to I . Because

LIM

1934fe

8

LT1934/LT1934-1

APPLICATIONS INFORMATION

Table 2. Inductor Vendors

VENDOR

Murata

PHONE

URL

PART SERIES

COMMENTS

Small, Low Cost, 2mm Height

(404) 426-1300

(847) 956-0666

www.murata.com

www.sumida.com

LQH3C

Sumida

CR43

CDRH4D28

CDRH5D28

Coilcraft

(847) 639-6400

(866) 362-6673

www.coilcraft.com

www.we-online.com

DO1607C

DO1608C

DT1608C

Würth

WE-PD1, 2, 3, 4

Electronics

the average inductor current equals the load current, the

maximum load current is:

The inductor must carry the peak current without satu-

rating excessively. When an inductor carries too much

current, its core material can no longer generate ad-

ditional magnetic ﬂux (it saturates) and the inductance

drops, sometimes very rapidly with increasing current.

This condition allows the inductor current to increase

at a very high rate, leading to high ripple current and

decreased overload protection.

I

= I – ΔI /2

PK L

OUT(MAX)

where I is the peak inductor current and ΔI is the

PK

L

peak-to-peak ripple current in the inductor. The ripple

current is determined by the off time, t

the inductor value:

= 1.8μs, and

OFF

ΔI = (V

+ V ) • t /L

D OFF

Inductorvendorsprovidecurrentratingsforpowerinduc-

tors. These are based on either the saturation current or

on the RMS current that the inductor can carry without

dissipating too much power. In some cases it is not clear

whichofthesetwodeterminethecurrentrating.Somedata

sheets are more thorough and show two current ratings,

one for saturation and one for dissipation. For LT1934 ap-

plications, the RMS current rating should be higher than

the load current, while the saturation current should be

higher than the peak inductor current calculated above.

L

OUT

I

is nominally equal to I . However, there is a slight

LIM

PK

delay in the control circuitry that results in a higher peak

current and a more accurate value is:

I

= I + 150ns • (V – V )/L

LIM IN OUT

PK

These expressions are combined to give the maximum

load current that the LT1934 will deliver:

I

= 350mA + 150ns • (V – V )/L – 1.8μs

IN OUT

OUT(MAX)

• (V

+ V )/2L (LT1934)

OUT

D

Input Capacitor

I

= 90mA + 150ns • (V – V )/L – 1.8μs

IN OUT

D

OUT(MAX)

• (V

+ V )/2L (LT1934-1)

OUT

Step-down regulators draw current from the input sup-

ply in pulses with very fast rise and fall times. The input

capacitor is required to reduce the resulting voltage ripple

at the LT1934 and to force this switching current into

a tight local loop, minimizing EMI. The input capacitor

must have low impedance at the switching frequency to

do this effectively. A 2.2μF ceramic capacitor (1μF for the

LT1934-1) satisﬁes these requirements.

Theminimumcurrentlimitisusedheretobeconservative.

The third term is generally larger than the second term,

so that increasing the inductor value results in a higher

output current. This equation can be used to evaluate

a chosen inductor or it can be used to choose L for a

givenmaximumloadcurrent.Thesimple,singleequation

rule given above for choosing L was found by setting

ΔI =I /2.5.ThisresultsinI

~0.8I (ignoring

L

LIM

OUT(MAX)

LIM

If the input source impedance is high, a larger value ca-

pacitor may be required to keep input ripple low. In this

case, an electrolytic of 10μF or more in parallel with a 1μF

the delay term). Note that this analysis assumes that the

inductor current is continuous, which is true if the ripple

current is less than the peak current or ΔI < I .

L

PK

ceramic is a good combination. Be aware that the input

1934fe

9

LT1934/LT1934-1

APPLICATIONS INFORMATION

capacitor is subject to large surge currents if the LT1934

circuit is connected to a low impedance supply, and that

some electrolytic capacitors (in particular tantalum) must

be speciﬁed for such use.

The LT1934-1, with its lower switch current, can use a

B-case tantalum capacitor.

With a high quality capacitor ﬁltering the ripple current

from the inductor, the output voltage ripple is determined

by the hysteresis and delay in the LT1934’s feedback

comparator. This ripple can be reduced further by adding

a small (typically 10pF) phase lead capacitor between the

output and the feedback pin.

Output Capacitor and Output Ripple

Theoutputcapacitorﬁlterstheinductor’sripplecurrentand

stores energy to satisfy the load current when the LT1934

is quiescent. In order to keep output voltage ripple low, the

impedance of the capacitor must be low at the LT1934’s

switching frequency. The capacitor’s equivalent series

resistance (ESR) determines this impedance. Choose one

with low ESR intended for use in switching regulators. The

contribution to ripple voltage due to the ESR is approxi-

Ceramic Capacitors

Ceramic capacitors are small, robust and have very low

ESR. However, ceramic capacitors can cause problems

when used with the LT1934.

Not all ceramic capacitors are suitable. X5R and X7R

types are stable over temperature and applied voltage

and give dependable service. Other types (Y5V and Z5U)

have very large temperature and voltage coefﬁcients of

capacitance. In the application circuit they may have only

a small fraction of their nominal capacitance and voltage

ripple may be much larger than expected.

mately I • ESR. ESR should be less than ~150mΩ for

LIM

the LT1934 and less than ~500mΩ for the LT1934-1.

The value of the output capacitor must be large enough

to accept the energy stored in the inductor without a large

changeinoutputvoltage. Settingthisvoltagestepequalto

1% of the output voltage, the output capacitor must be:

2

C

OUT

> 50 • L • (I /V

)

LIM OUT

Ceramiccapacitorsarepiezoelectric.TheLT1934’sswitch-

ing frequency depends on the load current, and at light

loads the LT1934 can excite the ceramic capacitor at audio

frequencies, generating audible noise. If this is unaccept-

able, use a high performance electrolytic capacitor at the

output. The input capacitor can be a parallel combination

of a 2.2μF ceramic capacitor and a low cost electrolytic

capacitor. The level of noise produced by the LT1934-1

For example, an LT1934 producing 3.3V with L = 47μH

requires 33μF. This value can be relaxed if small circuit

size is more important than low output ripple.

Sanyo’s POSCAP series in B-case and C-case sizes

provides very good performance in a small package for

the LT1934. Similar performance in traditional tantalum

capacitors requires a larger package (C- or D-case).

Table 3. Capacitor Vendors

VENDOR

PHONE

URL

PART SERIES

COMMENTS

Panasonic

(714) 373-7366

www.panasonic.com

Ceramic,

Polymer,

Tantalum

EEF Series

Kemet

Sanyo

(864) 963-6300

(408) 749-9714

www.kemet.com

Ceramic,

Tantalum

T494, T495

POSCAP

www.sanyovideo.com Ceramic,

Polymer,

Tantalum

Murata

AVX

(404) 436-1300

www.murata.com

www.avxcorp.com

Ceramic,

Tantalum

TPS Series

Taiyo Yuden (864) 963-6300

www.taiyo-yuden.com Ceramic

1934fe

10

LT1934/LT1934-1

APPLICATIONS INFORMATION

when used with ceramic capacitors will be lower and may

be acceptable.

D2

BOOST

LT1934

C3

A ﬁnal precaution regarding ceramic capacitors concerns

themaximuminputvoltageratingoftheLT1934.Aceramic

input capacitor combined with trace or cable inductance

forms a high quality (under damped) tank circuit. If the

LT1934 circuit is plugged into a live supply, the input volt-

agecanringtotwiceitsnominalvalue,possiblyexceeding

the LT1934’s rating. This situation is easily avoided; see

the Hot Plugging Safely section.

V

IN

V

OUT

V

SW

IN

GND

V

– V V

SW OUT

BOOST

MAX V

V + V

IN OUT

BOOST

(2a)

D2

C3

BOOST

LT1934

Catch Diode

V

IN

V

OUT

V

SW

IN

A 0.5A Schottky diode is recommended for the catch

diode, D1. The diode must have a reverse voltage rating

equal to or greater than the maximum input voltage. The

ON Semiconductor MBR0540 is a good choice; it is rated

for 0.5A forward current and a maximum reverse voltage

of 40V.

GND

1934 F02

V

– V V

BOOST

SW

IN

MAX V

2V

BOOST

(2b)

Figure 2. Two Circuits for Generating the Boost Voltage

Schottky diodes with lower reverse voltage ratings usu-

ally have a lower forward drop and may result in higher

efﬁciency with moderate to high load currents. However,

thesediodesalsohavehigherleakagecurrents.Thisleakage

current mimics a load current at the output and can raise

the quiescent current of the LT1934 circuit, especially at

elevated temperatures.

the maximum duty cycle as outlined above. For proper

start-up, the minimum input voltage is also limited by the

boost circuit. If the input voltage is ramped slowly, or the

LT1934 is turned on with its SHDN pin when the output

is already in regulation, then the boost capacitor may not

be fully charged. Because the boost capacitor is charged

with the energy stored in the inductor, the circuit will rely

on some minimum load current to get the boost circuit

running properly. This minimum load will depend on input

and output voltages, and on the arrangement of the boost

circuit. The minimum load generally goes to zero once the

circuit has started. Figure 3 shows a plot of minimum load

to start and to run as a function of input voltage. In many

cases the discharged output capacitor will present a load

to the switcher which will allow it to start. The plots show

BOOST Pin Considerations

Capacitor C3 and diode D2 are used to generate a boost

voltagethatishigherthantheinputvoltage. Inmostcases

a 0.1μF capacitor and fast switching diode (such as the

1N4148 or 1N914) will work well. Figure 2 shows two

ways to arrange the boost circuit. The BOOST pin must

be more than 2.5V above the SW pin for best efﬁciency.

For outputs of 3.3V and above, the standard circuit (Fig-

ure 2a) is best. For outputs between 2.8V and 3V, use a

0.22μF capacitor and a small Schottky diode (such as the

BAT-54). For lower output voltages the boost diode can be

tiedtotheinput(Figure2b). ThecircuitinFigure2aismore

efﬁcientbecausetheBOOSTpincurrentcomesfromalower

voltage source. You must also be sure that the maximum

voltage rating of the BOOST pin is not exceeded.

theworst-casesituationwhereV isrampingveryslowly.

IN

Use a Schottky diode (such as the BAT-54) for the lowest

start-up voltage.

At light loads, the inductor current becomes discontinu-

ous and the effective duty cycle can be very high. This

reduces the minimum input voltage to approximately

300mV above V . At higher load currents, the inductor

OUT

The minimum operating voltage of an LT1934 applica-

tion is limited by the undervoltage lockout (~3V) and by

current is continuous and the duty cycle is limited by the

1934fe

11

LT1934/LT1934-1

APPLICATIONS INFORMATION

Minimum Input Voltage V_OUT= 3.3V

to V ), then the LT1934’s internal circuitry will pull its

IN

6.0

quiescent current through its SW pin. This is ﬁne if your

system can tolerate a few mA in this state. If you ground

the SHDN pin, the SW pin current will drop to essentially

LT1934

OUT

T = 25°C

A

V

= 3.3V

5.5

5.0

4.5

4.0

3.5

3.0

BOOST DIODE TIED TO OUTPUT

TO START

zero. However, if the V pin is grounded while the output

IN

V

IN

is held high, then parasitic diodes inside the LT1934 can

pull large currents from the output through the SW pin

and the V pin. Figure 4 shows a circuit that will run only

IN

V

IN

TO RUN

whentheinputvoltageispresentandthatprotectsagainst

a shorted or reversed input.

D4

0.1

1

10

100

5

4

1

6

V

IN

V

BOOST

SW

IN

LOAD CURRENT (mA)

1934 G12

LT1934

100k

1M

V

OUT

SHDN

Minimum Input Voltage V_OUT= 5V

GND

2

FB

3

8

7

6

5

4

LT1934

V

= 5V

OUT

A

BACKUP

T

= 25°C

BOOST DIODE TIED TO OUTPUT

V

TO START

D4: MBR0530

IN

1934 F07

Figure 4. Diode D4 Prevents a Shorted Input from Discharging

a Backup Battery Tied to the Output; It Also Protects the Circuit

from a Reversed Input. The LT1934 Runs Only When the Input

is Present

V

IN

TO RUN

PCB Layout

0.1

1

10

100

LOAD CURRENT (mA)

For proper operation and minimum EMI, care must be

taken during printed circuit board layout. Figure 5 shows

the high current paths in the buck regulator circuit. Note

that large, switched currents ﬂow in the power switch,

the catch diode (D1) and the input capacitor (C2). The

loop formed by these components should be as small as

possible. Furthermore, the system ground should be tied

to the regulator ground in only one place; this prevents

the switched current from injecting noise into the system

ground. These components, along with the inductor and

output capacitor, should be placed on the same side of

the circuit board, and their connections should be made

on that layer. Place a local, unbroken ground plane below

these components, and tie this ground plane to system

ground at one location, ideally at the ground terminal of

the output capacitor C1. Additionally, the SW and BOOST

nodes should be kept as small as possible. Finally, keep

the FB node as small as possible so that the ground pin

1934 G13

Figure 3. The Minimum Input Voltage Depends

on Output Voltage, Load Current and Boost Circuit

maximum duty cycle of the LT1934, requiring a higher

input voltage to maintain regulation.

Shorted Input Protection

If the inductor is chosen so that it won’t saturate exces-

sively, an LT1934 buck regulator will tolerate a shorted

output. There is another situation to consider in systems

where the output will be held high when the input to the

LT1934 is absent. This may occur in battery charging ap-

plications or in battery backup systems where a battery

or some other supply is diode OR-ed with the LT1934’s

output. If the V pin is allowed to ﬂoat and the SHDN pin

is held high (either by a logic signal or because it is tied

IN

1934fe

12

LT1934/LT1934-1

APPLICATIONS INFORMATION

V

IN

SW

V

SW

IN

GND

(5a)

(5b)

I

C1

V

SW

L1

V

IN

SW

C2

D1

C1

GND

1934 F05

(5c)

Figure 5. Subtracting the Current When the Switch is On (a) from the Current When the Switch is Off (b) Reveals the Path of the High

Frequency Switching Current (c). Keep This Loop Small. The Voltage on the SW and BOOST Nodes Will Also be Switched; Keep These

Nodes as Small as Possible. Finally, Make Sure the Circuit is Shielded with a Local Ground Plane

SHUTDOWN

V

IN

V

OUT

SYSTEM

GROUND

1934 F06

VIAS TO LOCAL GROUND PLANE

OUTLINE OF LOCAL GROUND PLANE

Figure 6. A Good PCB Layout Ensures Proper, Low EMI Operation

and ground traces will shield it from the SW and BOOST

is plugged into a live supply (see Linear Technology

Application Note 88 for a complete discussion). The low

loss ceramic capacitor combined with stray inductance in

series with the power source forms an under damped tank

nodes. Figure 6 shows component placement with trace,

ground plane and via locations. Include two vias near

the GND pin of the LT1934 to help remove heat from the

LT1934 to the ground plane.

circuit, and the voltage at the V pin of the LT1934 can

IN

ringtotwicethenominalinputvoltage,possiblyexceeding

the LT1934’s rating and damaging the part. If the input

supply is poorly controlled or the user will be plugging

the LT1934 into an energized supply, the input network

should be designed to prevent this overshoot.

Hot Plugging Safely

The small size, robustness and low impedance of ceramic

capacitors make them an attractive option for the input

bypass capacitor of LT1934 and LT1934-1 circuits. How-

ever, these capacitors can cause problems if the LT1934

1934fe

13

LT1934/LT1934-1

APPLICATIONS INFORMATION

Figure 7 shows the waveforms that result when an LT1934 an aluminum electrolytic capacitor has been added. This

circuit is connected to a 24V supply through six feet of capacitor’s high equivalent series resistance damps the

24-gauge twisted pair. The ﬁrst plot is the response with circuit and eliminates the voltage overshoot. The extra

a 2.2μF ceramic capacitor at the input. The input voltage capacitor improves low frequency ripple ﬁltering and can

rings as high as 35V and the input current peaks at 20A. slightly improve the efﬁciency of the circuit, though it is

One method of damping the tank circuit is to add another likelytobethelargestcomponentinthecircuit. Analterna-

capacitor with a series resistor to the circuit. In Figure 7b tive solution is shown in Figure 7c. A 1Ω resistor is added

CLOSING SWITCH

SIMULATES HOT PLUG

I

IN

V

IN

LT1934

2.2μF

V

IN

10V/DIV

+

I

IN

10A/DIV

LOW

STRAY

IMPEDANCE

ENERGIZED

24V SUPPLY

INDUCTANCE

DUE TO 6 FEET

(2 METERS) OF

TWISTED PAIR

10μs/DIV

(7a)

LT1934

2.2μF

+

10μF

35V

AI.EI.

(7b)

1Ω

LT1934

2.2μF

0.1μF

(7c)

(7d)

LT1934-1

1μF

4.7Ω

LT1934-1

1μF

0.1μF

1934 F07

(7e)

Figure 7. A Well Chosen Input Network Prevents Input Voltage Overshoot and

Ensures Reliable Operation When the LT1934 is Connected to a Live Supply

1934fe

14

LT1934/LT1934-1

APPLICATIONS INFORMATION

in series with the input to eliminate the voltage overshoot

(it also reduces the peak input current). A 0.1μF capacitor

improves high frequency ﬁltering. This solution is smaller

andlessexpensivethantheelectrolyticcapacitor. Forhigh

input voltages its impact on efﬁciency is minor, reducing

efﬁciency less than one half percent for a 5V output at full

load operating from 24V.

estimated by calculating the total power loss from an

efﬁciency measurement and subtracting the catch diode

loss. The resulting temperature rise at full load is nearly

independentofinputvoltage. Thermalresistancedepends

on the layout of the circuit board, but a value of 150°C/W

is typical for the TSOT-23 and 75°C/W for the DFN.

The temperature rise for an LT1934 (TSOT-23) producing

5V at 250mA is approximately 25°C, allowing it to deliver

full load to 100°C ambient. Above this temperature the

load current should be reduced. For 3.3V at 250mA the

temperature rise is 15°C. The DFN temperature rise will

be roughly one-half of these values.

Voltage overshoot gets worse with reduced input capaci-

tance. Figure 7d shows the hot plug response with a 1μF

ceramic input capacitor, with the input ringing above 40V.

The LT1934-1 can tolerate a larger input resistance, such

as shown in Figure 7e where a 4.7Ω resistor damps the

voltage transient and greatly reduces the input current

glitch on the 24V supply.

Finally, be aware that at high ambient temperatures the

external Schottky diode, D1, is likely to have signiﬁcant

leakage current, increasing the quiescent current of the

LT1934 converter.

High Temperature Considerations

The die temperature of the LT1934 must be lower than the

maximum rating of 125°C. This is generally not a concern

unless the ambient temperature is above 85°C. For higher

temperatures, care should be taken in the layout of the

circuit to ensure good heat sinking of the LT1934. The

maximum load current should be derated as the ambient

temperature approaches 125°C.

Outputs Greater Than 6V

Foroutputsgreaterthan6V, tieadiode(suchasa1N4148)

from the SW pin to V to prevent the SW pin from ringing

IN

above V during discontinuous mode operation. The 12V

IN

outputcircuitinTypicalApplicationsshowsthelocationof

this diode. Also note that for outputs above 6V, the input

voltage range will be limited by the maximum rating of

the BOOST pin. The 12V circuit shows how to overcome

this limitation using an additional Zener diode.

ThedietemperatureiscalculatedbymultiplyingtheLT1934

power dissipation by the thermal resistance from junction

to ambient. Power dissipation within the LT1934 can be

1934fe

15

LT1934/LT1934-1

TYPICAL APPLICATIONS

3.3V Step-Down Converter

D2

0.1μF

L1

100μH

BOOST

V

OUT

V

IN

V

SW

FB

3.3V

IN

4.5V TO 34V

45mA

C2

1μF

D1

LT1934-1

10pF

1M

+

C1

22μF

ON OFF

SHDN

GND

604k

C1: TAIYO YUDEN JMK316BJ226ML

C2: TAIYO YUDEN GMK316BJ105ML

1934 TA04

D1: ZETEX ZHCS400 OR ON SEMI MBR0540

D2: CENTRAL CMDSH-3

L1: COILCRAFT DO1608C-104 OR

WURTH ELECTRONICS WE-PD4 TYPE S

5V Step-Down Converter

D2

0.1μF

L1

150μH

BOOST

V

OUT

V

IN

V

SW

FB

5V

IN

6.5V TO 34V

45mA

C2

1μF

D1

LT1934-1

10pF

1M

+

C1

22μF

ON OFF

SHDN

GND

332k

C1: TAIYO YUDEN JMK316BJ226ML

C2: TAIYO YUDEN GMK316BJ105ML

1934 TA05

D1: ZETEX ZHCS400 OR ON SEMI MBR0540

D2: CENTRAL CMPD914

L1: COILCRAFT DO1608C-154 OR

WURTH ELECTRONICS WE-PD4 TYPE S

1934fe

16

LT1934/LT1934-1

TYPICAL APPLICATIONS

1.8V Step-Down Converter

D2

0.1μF

L1

BOOST

LT1934

33μH

V

OUT

V

IN

V

SW

FB

1.8V

IN

3.6V TO 16V

250mA

C2

2.2μF

D1

147k

332k

+

C1

100μF

ON OFF

SHDN

GND

C1: SANYO 2R5TPB100M

1934 TA06

C2: TAIYO YUDEN EMK316BJ225ML

D1: ZETEX ZHCS400 OR ON SEMI MBR0540

D2: CENTRAL CMPD914

L1: SUMIDA CR43-330

Loop Powered 3.3V Supply with Additional Isolated Output

ISOLATED

OUT

D3

3V

+

3mA

L1B

50μH

10μF

•

D2

C1

L1A

50μH

BOOST

V

OUT

IN

V

SW

3V

14V TO 32V

<3.6mA

•

IN

9mA

10pF

1M

D1

LT1934-1

D4

10V

+

1μF

SHDN

GND

FB

33μF

390k

715k

D1: ON SEMICONDUCTOR MBR0540

D2, D3: BAT54

1934 TA08

D4: CENTRAL CMPZ5240B

L1: COILTRONICS CTX50-1

ZENER DIODE D4 PROVIDES AN UNDERVOLTAGE LOCKOUT,

REDUCING THE INPUT CURRENT REQUIRED AT START-UP

1934fe

17

LT1934/LT1934-1

TYPICAL APPLICATIONS

Standalone 350mA Li-Ion Battery Charger

D2

0.1μF

L1

47μH

1k

10k

0.047μF

BOOST

D3

1k

V

IN

V

IN

7V TO 28V

V

SW

FB

IN

CHRG

GATE

0.022μF

1M

D1

LT1934

LTC4052

ACPR SENSE

BAT

C2

1μF

SHDN

GND

+

C1

47μF

350mA

332k

TIMER GND

1-CELL 4.2V

Li-Ion

BATTERY

+

C

C5

10μF

TIMER

0.1μF

1934 TA07a

C1: SANYO 6TPB47M

C2: TAIYO YUDEN GMK316BJ105ML

(619) 661-6835

(408) 573-4150

CHARGE STATUS

AC PRESENT

D1, D3: ON SEMICONDUCTOR MBR0540 (602) 244-6600

D2: CENTRAL CMDSH-3

L1: SUMIDA CR43-470

(516) 435-1110

(847) 956-0667

500

400

300

200

100

0

V

= 24V

IN

V

= 8V

IN

= 12V

IN

2.5

3

3.5

4

4.5

BATTERY VOLTAGE (V)

1934 TA07b

12V Step-Down Converter

D2

0.1μF

D4

D3

L1

100μH

BOOST

V

OUT

V

IN

V

SW

FB

12V

IN

15V TO 32V

170mA

C2

2.2μF

LT1934

D1

866k

100k

+

C1

22μF

ON OFF

SHDN

GND

C1: KEMET T495D226K020AS

1934 TA09

C2: TAIYO YUDEN GMK325BJ225MN

D1: ON SEMI MBR0540

D2, D4: CENTRAL CMPD914

D3: CENTRAL CMPZ5234B 6.2V ZENER

L1: TDK SLF6028T-101MR42

1934fe

18

LT1934/LT1934-1

PACKAGE DESCRIPTION

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

1.50 – 1.75

(NOTE 4)

2.80 BSC

1.4 MIN

3.85 MAX 2.62 REF

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 0302 REV B

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

DCB Package

6-Lead Plastic DFN (2mm × 3mm)

(Reference LTC DWG # 05-08-1715)

R = 0.115

TYP

2.00 0.10

(2 SIDES)

0.40 0.10

R = 0.05

TYP

4

6

0.70 0.05

1.65 0.05

(2 SIDES)

3.00 0.10 1.65 0.10

(2 SIDES)

3.55 0.05

2.15 0.05

PIN 1 BAR

TOP MARK

(SEE NOTE 6)

PIN 1 NOTCH

R0.20 OR 0.25

s 45° CHAMFER

(DCB6) DFN 0405

PACKAGE

OUTLINE

3

1

0.25 0.05

0.50 BSC

0.75 0.05

0.200 REF

1.35 0.10

(2 SIDES)

1.35 0.05

(2 SIDES)

BOTTOM VIEW—EXPOSED PAD

0.00 – 0.05

RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS

NOTE:

1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (TBD)

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

1934fe

19

LT1934/LT1934-1

TYPICAL APPLICATION

5V Step-Down Converter

D2

0.1μF

L1

68μH

BOOST

V

OUT

V

IN

V

SW

FB

5V

IN

6.5V TO 34V

250mA

C2

2.2μF

D1

LT1934

10pF

1M

+

C1

68μF

ON OFF

SHDN

GND

332k

C1: SANYO 6TPB68M

C2: TAIYO YUDEN GMK325BJ225MN

1934 TA03

D1: ZETEX ZHCS400 OR ON SEMI MBR0540

D2: CENTRAL CMPD914

L1: SUMIDA CDRH5D28-680

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

LT1616

25V, 500mA (I ), 1.4MHz, High Efﬁciency

Step-Down DC/DC Converter

V

= 3.6V to 25V, V

= 1.25V, I = 1.9mA, I < 1μA,

Q SD

OUT

IN

OUT

ThinSOT Package

LT1676

LT1765

LT1766

LT1767

LT1776

LTC^®1877

LTC1879

LT1956

60V, 440mA (I ), 100kHz, High Efﬁciency

Step-Down DC/DC Converter

V

= 7.4V to 60V, V

= 1.24V, I = 3.2mA, I = 2.5μA,

Q SD

OUT

IN

OUT

S8 Package

25V, 2.75A (I ), 1.25MHz, High Efﬁciency

V

= 3V to 25V, V = 1.2V, I = 1mA, I = 15μA,

OUT Q SD

OUT

IN

Step-Down DC/DC Converter

S8, TSSOP16E Packages

V = 5.5V to 60V, V = 1.2V, I = 2.5mA, I = 25μA,

IN

60V, 1.2A (I ), 200kHz, High Efﬁciency

OUT

Q

SD

Step-Down DC/DC Converter

TSSOP16/E Package

= 3V to 25V; V = 1.2V, I = 1mA, I = 6μA,

OUT Q SD

25V, 1.2A (I ), 1.25MHz, High Efﬁciency

V

OUT

IN

Step-Down DC/DC Converter

MS8/E Packages

40V, 550mA (I ), 200kHz, High Efﬁciency

V

= 7.4V to 40V; V

= 1.24V, I = 3.2mA, I = 30μA,

OUT Q SD

OUT

IN

Step-Down DC/DC Converter

N8, S8 Packages

600mA (I ), 550kHz, Synchronous

V

= 2.7V to 10V; V

= 0.8V, I = 10μA, I < 1μA,

Q SD

OUT

IN

OUT

Step-Down DC/DC Converter

MS8 Package

1.2A (I ), 550kHz, Synchronous

V

= 2.7V to 10V; V

= 0.8V, I = 15μA, I < 1μA,

Q SD

OUT

IN

Step-Down DC/DC Converter

TSSOP16 Package

60V, 1.2A (I ), 500kHz, High Efﬁciency

V

= 5.5V to 60V, V

= 1.2V, I = 2.5mA, I = 25μA,

Q SD

OUT

IN

Step-Down DC/DC Converter

TSSOP16/E Package

= 2.7V to 6V, V = 0.8V, I = 20μA, I < 1μA,

OUT Q SD

LTC3405/LTC3405A 300mA (I ), 1.5MHz, Synchronous

V

OUT

IN

Step-Down DC/DC Converter

ThinSOT Package

LTC3406/LTC3406B 600mA (I ), 1.5MHz, Synchronous

V

= 2.5V to 5.5V, V

= 0.6V, I = 20μA, I < 1μA,

OUT Q SD

OUT

IN

Step-Down DC/DC Converter

ThinSOT Package

LTC3411

LTC3412

LTC3430

1.25A (I ), 4MHz, Synchronous

Step-Down DC/DC Converter

V

= 2.5V to 5.5V, V

= 0.8V, I = 60μA, I < 1μA,

Q SD

OUT

IN

OUT

MS Package

2.5A (I ), 4MHz, Synchronous

V

= 2.5V to 5.5V, V

= 0.8V, I = 60μA, I < 1μA,

Q SD

OUT

IN

Step-Down DC/DC Converter

TSSOP16E Package

60V, 2.75A (I ), 200kHz, High Efﬁciency

V

= 5.5V to 60V, V

= 1.2V, I = 2.5mA, I = 30μA,

Q SD

OUT

IN

Step-Down DC/DC Converter

TSSOP16E Package

1934fe

LT 0209 REV E • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

20

●

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


型号：	LT1934IS6-1#TRM
厂家：	Linear
描述：	IC 0.16 A SWITCHING REGULATOR, PDSO6, 1 MM HEIGHT, PLASTIC, MO-193, TSOT-23, 6 PIN, Switching Regulator or Controller 开关光电二极管
文件：	总20页 (文件大小：229K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LT1934IS6-1#TRM [Linear]

相关型号：

LT1934IS6-1#TRMPBF

LT1934_15

LT1935

LT1935

LT1935ES5

LT1935ES5

LT1935ES5#PBF

LT1935ES5#TRM

LT1935ES5#TRMPBF

LT1936

LT1936EMS8E

LT1936EMS8E#TR