LT1611CS5#TRMPBF_技术文档

LT1611

Inverting 1.4MHz Switching

Regulator in SOT-23

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DESCRIPTIO

FEATURES

TheLT^®1611istheindustry’sfirstinverting5-leadSOT-23

current mode DC/DC converter. Intended for use in small,

low power applications, it operates from an input voltage

as low as 1.1V and switches at 1.4MHz, allowing the use

of tiny, low cost capacitors and inductors 2mm or less in

height. Its small size and high switching frequency enable

the complete DC/DC converter function to consume less

than 0.25 square inches of PC board area. Capable of

generating –5V at 150mA from a 5V supply or –5V at

100mAfroma3Vsupply,theLT1611replacesnonregulated

“charge pump” solutions in many applications.

■

Very Low Noise: 1mV_P–POutput Ripple

■

–5V at 150mA from a 5V Input

■

Better Regulation Than a Charge Pump

■

Effective Output Impedance: 0.14Ω

■

Uses Tiny Capacitors and Inductors

■

Internally Compensated

■

Fixed Frequency 1.4MHz Operation

■

Low Shutdown Current: <1µA

■

Low V_CESATSwitch: 300mV at 300mA

■

Tiny 5-Lead SOT-23 Package

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The LT1611 operates in a dual inductor inverting topology

which filters the input side as well as the output side of the

DC/DC converter. Fixed frequency switching ensures a

cleanoutputfreefromlowfrequencynoisetypicallypresent

with charge pump solutions. No load quiescent current of

the LT1611 is 3mA, while in shutdown quiescent current

drops to 0.5µA. The 36V switch allows V_INto V_OUT

differential of up to 33V.

APPLICATIO S

■

MR Head Bias

■

Digital Camera CCD Bias

■

LCD Bias

GaAs FET Bias

Positive-to-Negative Conversion

■

The LT1611 is available in the 5-lead SOT-23 package.

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

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TYPICAL APPLICATIO

C2

L1A

22µH

L1B

22µH

Transient Response

1µF

V

IN

5V

D1

V

SW

OUT

IN

–5V

SHDN

LT1611

150mA

R1

29.4k

V_OUT

20mV/DIV

AC COUPLED

+

1200pF

C1

22µF

C3

22µF

NFB

GND

R2

10k

150mA

LOAD CURRENT

50mA

C1: AVX TAJB226M010

C2: TAIYO YUDEN LMK212BJ105MG

1611 TA01

100µs/DIV

1611 F10

C3: TAIYO YUDEN JMK325BJ226MM (1210 SIZE)

D1: MBR0520

L1: SUMIDA CLS62-220 OR 2× MURATA LQH3C220 (UNCOUPLED)

Figure 1. 5V to –5V, 150mA Low Noise Inverting DC/DC Converter

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LT1611

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ABSOLUTE MAXIMUM RATINGS

PACKAGE/ORDER INFORMATION

(Note 1)

ORDER PART

NUMBER

V_INVoltage .............................................................. 10V

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

NFB Voltage ............................................................. –3V

Current into NFB Pin ............................................. ±1mA

SHDN Voltage .......................................................... 10V

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

Operating Temperature Range

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

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

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

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

TOP VIEW

SW 1

GND 2

NFB 3

5 V

IN

LT1611CS5

4 SHDN

S5 PACKAGE

5-LEAD PLASTIC SOT-23

S5 PART MARKING

LTES

T_JMAX= 125°C, θ_JA= 256°C/W

Consult factory for Industrial and Military grade parts.

ELECTRICAL CHARACTERISTICS ^The● denotes the specifications which apply over the full operating

temperature range, otherwise specifications are at T_A= 25°C. V_IN= 1.5V, V_SHDN= V_INunless otherwise noted.

PARAMETER

CONDITIONS

MIN

TYP

MAX

1.1

UNITS

V

Minimum Operating Voltage

Maximum Operating Voltage

NFB Pin Bias Current

Feedback Voltage

0.9

10

V

= –1.23V

●

–2.7

–4.7

–1.23

3

–6.7

–1.255

4.5

µA

V

NFB

–1.205

Quiescent Current

= 1.5V, Not Switching

mA

SHDN

Quiescent Current in Shutdown

V

= 0V, V = 2V

0.01

0.5

1.0

µA

SHDN

IN

= 0V, V = 5V

IN

Reference Line Regulation

Switching Frequency

Maximum Duty Cycle

Switch Current Limit

1.5V ≤ V ≤ 10V

0.02

1.4

0.2

1.8

%/V

MHz

%

IN

●

1.0

82

86

(Note 3)

550

800

300

0.01

mA

mV

µA

Switch V

I

= 300mA

= 5V

350

1

CESAT

SW

Switch Leakage Current

SHDN Input Voltage High

SHDN Input Voltage Low

SHDN Pin Bias Current

V

SW

1

V

0.3

V

= 3V

= 0V

25

0

50

0.1

µA

SHDN

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a device may be impaired.

Note 3: Current limit guaranteed by design and/or correlation to static test.

Slope compensation reduces current limit at higher duty cycle.

Note 2: C grade device specifications are guaranteed over the 0°C to 70°C

temperature range. In addition, C grade device specifications are assured

over the –40°C to 85°C temperature range by design or correlation, but

are not production tested.

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LT1611

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TYPICAL PERFOR A CE CHARACTERISTICS

NFB Pin Bias Current vs

Temperature

Efficiency, V_OUT= –5V

V_NFBvs Temperature

85

80

75

70

65

60

55

50

–1.245

–1.240

–1.235

–1.230

–1.225

–1.220

–1.215

–1.210

6

5

4

3

2

1

0

V

= 5V

IN

V

= 3V

IN

0

50

75

100

125

150

25

–50

–25

0

25

50

75

100

–50

–25

0

25

50

75

100

LOAD CURRENT (mA)

TEMPERATURE (°C)

1611 G01

1611 G02

1611 G03

Switch V_CESATvs Switch Current

SHDN Pin Bias Current vs V_SHDN

Switch Current Limit vs Duty Cycle

700

600

500

400

300

200

100

0

900

50

40

30

20

10

0

T

= 25°C

T

= 25°C

A

800

700

600

500

400

300

200

100

0

100 200 300 400 500 600 700

SWITCH CURRENT (mA)

0

1

2

3

4

5

10

20

30

40

50

60

70

80

SHDN PIN VOLTAGE (V)

DUTY CYCLE (%)

1611 G04

1611 G05

1611 G06

Oscillator Frequency vs

Temperature

No-Load Operating Quiescent

Current vs Temperature*

Switch Current Limit vs

Temperature (Duty Cycle = 30%)

900

800

700

600

500

400

300

200

100

0

2.00

1.75

1.50

1.25

1.00

0.75

0.50

0.25

0

6.0

5.5

5.0

4.5

4.0

3.5

3.0

2.5

2.0

V

= 5V

IN

V

IN

= 1.5V

–50

–25

0

25

50

75

100

–50

–25

0

25

50

75

100

–50

–25

0

25

50

75

100

TEMPERATURE (°C)

1611 G07

1611 G09

1611 G08

* Includes bias current through R1, R2 and Schottky leakage current at T ≥ 75°C

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LT1611

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PIN FUNCTIONS

SW (Pin 1): Switch Pin. Minimize trace area at this pin to

V

− 1.23

OUT

keep EMI down.

R1=

1.23

−6

+

10

4.5•

GND (Pin 2): Ground. Tie directly to local ground plane.

R2

NFB (Pin 3): Negative Feedback Pin. Minimize trace area.

Reference voltage is –1.23V. Connect resistive divider tap

here. The suggested value for R2 is 10k. Set R1 and R2

according to:

SHDN (Pin 4): Shutdown Pin. Tie to 1V or more to enable

device. Ground to shut the device down.

V_IN(Pin 5): Input Supply Pin. Must be locally bypassed.

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BLOCK DIAGRAM

V

IN

5

IN

R5

40k

R6

40k

1

SW

+

–

COMPARATOR

A2

–

+

A1

m

DRIVER

g

FF

S

Q3

R

Q

R

C

RAMP

GENERATOR

Q1

Q2

x10

Σ

C

+

C

V

OUT

R3

30k

0.15Ω

A = 3

1.4MHz

OSCILLATOR

–

R1

C

PL

(OPTIONAL)

(EXTERNAL)

R4

140k

NFB

SHDN

4

SHUTDOWN

3

NFB

2

GND

R2

1611 BD

(EXTERNAL)

Figure 2

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OPERATIO

The LT1611 combines a current mode, fixed frequency

PWM architecture with a –1.23V reference to directly

regulate negative outputs. Operation can be best under-

stood by referring to the block diagram of Figure 2. Q1 and

Q2 form a bandgap reference core whose loop is closed

around the output of the converter. The driven reference

point is the lower end of resistor R4, which normally sits

at a voltage of –1.23V. As the load current changes, the

NFB pin voltage also changes slightly, driving the output

of g_mamplifier A1. Switch current is regulated directly on

a cycle-to-cycle basis by A1’s output. The flip-flop is set at

the beginning of each cycle, turning on the switch. When

thesummationofasignalrepresentingswitchcurrentand

a ramp generator (introduced to avoid subharmonic oscil-

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

signal, comparator A2 changes stage, resetting the flip-

flop and turning off the switch. Output voltage decreases

(the magnitude increases) as switch current is increased.

The output, attenuated by external resistor divider R1 and

R2, appears at the NFB pin, closing the overall loop.

Frequency compensation is provided internally by R_Cand

C_C. Transientresponsecanbeoptimizedbytheadditionof

a phase lead capacitor, C_PL, in parallel with R1 in applica-

tions where large value or low ESR output capacitors are

used.

As load current is decreased, the switch turns on for a

shorter period each cycle. If the load current is further

decreased, the converter will skip cycles to maintain

output voltage regulation.

The LT1611 can work in either of two topologies. The

simpler topology appends a capacitive level shift to a

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LT1611

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OPERATIO

boost converter, generating a negative output voltage,

which is directly regulated. The circuit schematic is de-

tailed in Figure 3. Only one inductor is required, and the

two diodes can be in a single SOT-23 package. Output

noise is the same as in a boost converter, because current

is delivered to the output only during the time when the

LT1611’s internal switch is off.

When Q1 turns off during the second phase of switching,

the SW node voltage abruptly increases to (V_IN+ |V_OUT|).

The SWX node voltage increases to V_D(about 350mV).

Nowcurrentinthefirstloop, beginingatC1, flowsthrough

L1,C2,D1andbacktoC1.Currentinthesecondloopflows

from C3 through L2, D1 and back to C3. Load current

continues to be supplied by L2 and C3.

If D2 is replaced by an inductor, as shown in Figure 4, a

higherperformancesolutionresults.Thisconvertertopol-

ogy was developed by Professor S. Cuk of the California

Institute of Technology in the 1970s. A low ripple voltage

results with this topology due to inductor L2 in series with

theoutput. Abruptchangesinoutputcapacitorcurrentare

eliminated because the output inductor delivers current to

the output during both the off-time and the on-time of the

LT1611switch. Withproperlayoutandhighqualityoutput

An important layout issue arises due to the chopped

natureofthecurrentsflowinginQ1andD1.Iftheyareboth

tied directly to the ground plane before being combined,

switching noise will be introduced into the ground plane.

Itisalmostimpossibletogetridofthisnoise,oncepresent

in the ground plane. The solution is to tie D1’s cathode to

the ground pin of the LT1611 before the combined cur-

rents are dumped into the ground plane as drawn in

Figures 4, 5 and 6. This single layout technique can

virtually eliminate high frequency “spike” noise so often

present on switching regulator outputs.

capacitors, output ripple can be as low as 1mV_P–P

.

The operation of Cuk’s topology is shown in Figures 5

and 6. During the first switching phase, the LT1611’s

switch, represented by Q1, is on. There are two current

loops in operation. The first loop begins at input capacitor

C1, flows through L1, Q1 and back to C1. The second loop

flows from output capacitor C3, through L2, C2, Q1 and

back to C3. The output current from R_LOADis supplied by

L2 and C3. The voltage at node SW is V_CESATand at node

SWX the voltage is –(V_IN+ |V_OUT|). Q1 must conduct both

L1 and L2 current. C2 functions as a voltage level shifter,

with an approximately constant voltage of (V_IN+ |V_OUT|)

across it.

Output ripple voltage appears as a triangular waveform

ridingonV_OUT. Ripplemagnitudeequalstheripplecurrent

of L2 multiplied by the equivalent series resistance (ESR)

of output capacitor C3. Increasing the inductance of L1

and L2 lowers the ripple current, which leads to lower

output voltage ripple. Decreasing the ESR of C3, by using

ceramic or other low ESR type capacitors, lowers output

ripple voltage. Output ripple voltage can be reduced to

arbitrarily low levels by using large value inductors and

low ESR, high value capacitors.

C2

1µF

C2

1µF

D2

L1

L2

V

IN

D1

V

SW

V

IN

SW

+

IN

+

–V

OUT

C1

LT1611

GND

R1

SHUTDOWN

SHDN

NFB

C3

+

GND

R2

10k

R2

10k

1611 F03

1611 F04

Figure 3. Direct Regulation of Negative Output

Using Boost Converter with Charge Pump

Figure 4. L2 Replaces D2 to Make Low Output Ripple

Inverting Topology. Coupled or Uncoupled Inductors Can

Be Used. Follow Phasing If Coupled for Best Results

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LT1611

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OPERATIO

V

–(V

+

V

OUT

)

CESAT

IN

C2

L1

L2

SW

SWX

V

IN

–V

OUT

D1

Q1

+

C1

C3

R

LOAD

+

1611 F05

Figure 5. Switch-On Phase of Inverting Converter. L1 and L2 Current Have Positive dI/dt

V

+

V

+ V

V

D

IN

OUT

D

C2

L1

L2

SW

SWX

V

–V

OUT

IN

D1

Q1

+

C1

C3

R

LOAD

+

1611 F06

Figure 6. Switch-Off Phase of Inverting Converter. L1 and L2 Current Have Negative dI/dt

Transient Response

tions due to load steps and output ripple voltage to very

low levels. To illustrate, Figure 7 shows an LT1611 invert-

ing converter with resistor loads R_L1and R_L2. R_L1is

connected across the output, while R_L2is switched in

externally via a pulse generator. Output voltage wave-

forms are pictured in subsequent figures, illustrating the

performance of output capacitor type and the effect of C_PL

connected across R1.

The inverting architecture of the LT1611 can generate a

very low ripple output voltage. Recently available high

value ceramic capacitors can be used successfully in

LT1611 designs with the addition of a phase lead capaci-

tor, C_PL(seeFigure7). Connectedinparallelwithfeedback

resistor R1, this capacitor reduces both output perturba-

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LT1611

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OPERATIO

C2

L1A

L1B

Figure 8 shows the output voltage with a 50mA to 150mA

load step, using an AVX TAJ “B” case 22µF tantalum

capacitor at the output. Output perturbation is approxi-

mately 100mV as the load changes from 50mA to 150mA.

Steady-state ripple voltage is 20mV_P–P, due to L1’s ripple

current and C3’s ESR. Step response can be improved by

adding a 3.3nF capacitor (C_PL) as shown in Figure 9.

Settling time improves from 150µs to 40µs, although

steady-state ripple voltage does not improve. Figure 10

pictures the output voltage and switch pin voltage at

200ns per division. Note the absence of high frequency

spikes at the output. This is easily repeatable with proper

layout, described in the next section.

1µF

22µH

V

IN

5V

D1

–V

OUT

V

SW

IN

SHDN

R

L2

50Ω

+

C

R1

PL

LT1611

GND

R

L1

100Ω

C1

NFB

C3

+

R2

10k

C1: AVX TAJB226M010

C2: TAIYO YUDEN LMK212BJ105MG

C3: SEE TEXT

D1: MBR0520

L1A, L1B: SUMIDA CLS62-220

1611 F07

Figure 7. Switching R_L2Provides 50mA to 150mA

Load Step for LT1611 5V to –5V Converter

V_OUT

50mV/DIV

V_OUT

20mV/DIV

AC COUPLED

150mA

50mA

150mA

LOAD CURRENT

50mA

LOAD CURRENT

100µs/DIV

1611 F08

20µs/DIV

1611 F09

Figure 8. Load Step Response of LT1611

with 22µF Tantalum Output Capacitor

Figure 9. Addition of C_PLto Figure 7’s Circuit

Improves Load Step Response. C_PL= 3.3nF

V_OUT

10mV/DIV

SWITCH VOLTAGE

5V/DIV

LOAD = 150mA

200ns/DIV

1611 F10

Figure 10. 22µF “B” Case Tantalum Capacitor (AVX TAJ “B” Series)

Has ESR Resulting in 20mV_P–PVoltage Ripple at Output

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LT1611

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OPERATIO

In Figure 11 (also shown on the first page), output capaci-

tor C3 is replaced by a ceramic unit. These large value

ceramic capacitors have ESR of about 2mΩ and result in

very low output ripple. At the 20mV/division scale, output

voltage ripple cannot be seen. Figure 12 pictures the

output and switch nodes at 200ns per division. The output

voltage ripple is approximately 1mV_P–P. Again, good

layout is mandatory to achieve this level of performance.

Layout

The LT1611 switches current at high speed, mandating

careful attention to layout for best performance. You will

not get advertised performance with careless layout. Figure 13

shows recommended component placement. Follow this

closely in your printed circuit layout. The cut ground

copper at D1’s cathode is essential to obtain the low noise

achieved in Figures 11 and 12’s oscillographs. Input

bypass capacitor C1 should be placed close to the LT1611

as shown. The load should connect directly to output

capacitor C2 for best load regulation. You can tie the local

ground into the system ground plane at C3’s ground

terminal.

V_OUT

5mV/DIV

AC COUPLED

V_OUT

20mV/DIV

AC COUPLED

SWITCH VOLTAGE

5V/DIV

150mA

LOAD CURRENT

50mA

100µs/DIV

1611 F11

LOAD = 150mA

200ns/DIV

1611 F12

Figure 11. Replacing C3 with 22µF Ceramic Capacitor

(Taiyo Yuden JMK325BJ226MM) Improves Output

Noise. C_PL= 1200pF Results in Best Phase Margin

Figure 12. 22µF Ceramic Capacitor at

Output Reduces Ripple to 1mV_P–P. Proper

Layout Is Essential to Achieve Low Noise

L1A

L1B

C1

–V

+

OUT

D1

C2

V

IN

C3

+

1

2

3

5

4

SHUTDOWN

R2

1611 F13

R1

GND

Figure 13. Suggested Component Placement. Note Cut in Ground Copper at D1’s Cathode

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LT1611

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OPERATIO

Start-Up/Soft-Start

measured at V_IN, is limited to a peak value of 450mA as the

time required to reach final value increases to 700µs. In

Figure 16, C_SSis increased to 0.1µF, resulting in a lower

peak input current of 240mA with a V_OUTramp time of

2.1ms. C_SScan be increased further for an even slower

ramp, if desired. Diode D2 serves to quickly discharge C_SS

when V_SSis driven low to shut down the device. D2 can be

omitted, resulting in a “soft-stop” slow discharge of the

output capacitor.

TheLT1611, startingfromV_OUT=0V,reachesfinalvoltage

in approximately 450µs after SHDN is pulled high, with

C_OUT=22µF,V_IN=5VandV_OUT=–5V.Chargingtheoutput

capacitor at this speed requires an inrush current of over

1A. If a longer start-up time is acceptable, a soft-start

circuit consisting of R_SSand C_SS, as shown in Figure 14,

can be used to limit inrush current to a lower value. Figure

15 pictures V_OUTand input current, starting into a 33Ω

load, with R_SSof 33kΩ and C_SSof 33nF. Input current,

C2

CURRENT

PROBE

L1A

22µH

L1B

1µF

22µH

V

IN

5V

D1

+

V

IN

SW

C1

22µF

V

OUT

–5V

R1

29.4k

C

P

R

LT1611

SS

1200pF

33k

C3

22µF

V

SS

SHDN

NFB

GND

R2

10k

D2

1N4148

C

SS

C1: AVX TAJB226M010

C2: TAIYO YUDEN LMK212BJ105MG

C3: TAIYO YUDEN JMK325BJ226MM (1210 SIZE)

D1: MBR0520

L1: SUMIDA CLS62-220 OR 2× MURATA LQH3C220 (UNCOUPLED)

33nF/0.1µF

1611 F14

V

OUT

Figure 14. R_SSand C_SSat SHDN Pin Provide Soft-Start to LT1611 Inverting Converter

V_OUT

2V/DIV

I_IN

200mA/DIV

V_S

5V/DIV

LOAD = 150mA

500µs/DIV

1611 F15

LOAD = 150mA

500µs/DIV

1611 F16

Figure 15. R_SS= 33k, C_SS= 33nF; V_OUTReaches

–5V in 750µs; Input Current Peaks at 450mA

Figure 16. R_SS= 33k, C_SS= 0.1µF; V_OUTReaches

–5V in 2.1ms; Input Current Peaks at 240mA

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OPERATIO

Output Current

COMPONENT SELECTION

Inductors

The LT1611 will deliver 150mA at –5V from a 5V ±10%

input supply. If a higher voltage supply is available, more

output current can be obtained. Figure 17’s schematic

shows how to get more current. Although the LT1611’s

maximum voltage allowed at V_INis 10V, the SW pin can

handle higher voltage (up to 36V). In Figure 17, the V_INpin

of the LT1611 is driven from a 5V supply, while input

inductor L_1Ais driven from a separate 12V supply. Figure

18’s graph shows maximum recommended output cur-

rent as the voltage on L_1Ais varied. Up to 300mA can be

delivered when driving L_1Afrom a 12V supply.

Each of the two inductors used with the LT1611 should

have a saturation current rating (where inductance is

approximately 70% of zero current inductance) of ap-

proximately 0.25A or greater. If the device is used in

“charge pump” mode, where there is only one inductor,

then its rating should be 0.5A or greater. DCR of the

inductors should be 0.5Ω or less. A value of 22µH is

suitable if using a coupled inductor such as Sumida

CLS62-220 or Coiltronics CTX20-1. If using two separate

inductors, increasing the value to 47µH will result in the

same ripple current. Inductance can be reduced if operat-

ing from a supply voltage below 3V. Table 1 lists several

inductors that will work with the LT1611, although this is

not an exhaustive list. There are many magnetics vendors

whose components are suitable.

V

L

(SEE TEXT)

350

300

250

L1A

C2

L1B

22µH

1µF

22µH

5V

D1

V

SW

OUT

IN

–5V

UP TO 300mA

SHDN

LT1611

29.4k

1200pF

C1

1µF

200

150

100

C3

22µF

NFB

GND

10k

C1, C2: TAIYO YUDEN LMK212BJ105MG

C3: TAIYO YUDEN JMK325BJ226MM

D1: MBR0520

1611 F17

3

4

5

6

7

8

9

10 11 12

V

(V)

L

1611 F18

L1A, L1B: SUMIDA CLS62-220

Figure 17. Increase Output Current By Driving L1A from a Higher Voltage

Figure 18. Output Current Increases to

300mA When Driving V_Lfrom 12V Supply

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OPERATIO

Capacitors

ceramic can be used with little trade-off in circuit perfor-

mance. Some capacitor types appropriate for use with the

LT1611 are listed in Table 2.

As described previously, ceramic capacitors can be used

with the LT1611 provided loop stability is considered. For

lower cost applications, small tantalum units can be used.

A value of 22µF is acceptable, although larger capacitance

values can be used. ESR is the most important parameter

inselectinganoutputcapacitor. The“flying”capacitor(C2

in the schematic figures) should be a 1µF ceramic type. An

X5R or X7R dielectric should be used to avoid capacitance

decreasing severely with applied voltage. The input by-

pass capacitor is less critical, and either tantalum or

Diodes

ASchottkydiodeisrecommendedforusewiththeLT1611.

The Motorola MBR0520 is a very good choice. Where the

input to output voltage differential exceeds 20V, use the

MBR0530 ( a 30V diode). If cost is more important than

efficiency, a 1N4148 can be used, but only at low current

loads.

Table 1. Inductor Vendors

VENDOR

PHONE

URL

PART

COMMENT

Sumida

(847) 956-0666

www.sumida.com

CLS62-22022

CD43-470

22µH Coupled

47µH

Murata

(404) 436-1300

(407) 241-7876

www.murata.com

LQH3C-220

CTX20-1

22µH, 2mm Height

Coiltronics

www.coiltronics.com

20µH Coupled, Low DCR

Table 2. Capacitor Vendors

VENDOR

Taiyo Yuden

AVX

PHONE

URL

PART

COMMENT

(408) 573-4150

(803) 448-9411

www.t-yuden.com

www.avxcorp.com

Ceramic Caps

X5R Dielectric

Ceramic Caps

Tantalum Caps

Murata

(404) 436-1300

www.murata.com

Ceramic Caps

U

TYPICAL APPLICATIO S

“Charge Pump” Inverting DC/DC Converter

C2

1µF

L1

10µH

3.3V

D2

D1

V

SW

IN

SHDN

LT1611

–5V

70mA

29.4k

10k

C1

1µF

C3

22µF

NFB

GND

C1, C2: TAIYO YUDEN LMK212BJ105MG

C3: TAIYO YUDEN JMK325BJ226MM

D1, D2: MBR0520

1611 TA02

L1: MURATA LQH3C-100

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-

tationthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.

11

LT1611

U

TYPICAL APPLICATIO S

4-Cell to –10V Inverting Converter

4-Cell to –10V Inverting Converter Efficiency

C2

1µF

85

80

L1A

15µH

L1B

15µH

V

IN

V

= 6.5V

IN

D1

75

70

65

60

55

50

V

SW

+

IN

C1

22µF

V

= 5V

V

IN

OUT

V

= 3.6V

–10V/60mA

IN

LT1611

68.1k

C3

6.8µF

SHUTDOWN

SHDN

NFB

+

GND

10k

C1: AVX TAJB226M010

C2: TAIYO YUDEN LMK212BJ105MG

C3: AVX TAJA685M016

(803) 946-0362

1611 TA03

0

25

50

75

100

125

150

D1: MOTOROLA MBR0520

L1: SUMIDA CL562-150

(800) 441-2447

(847) 956-0666

LOAD CURRENT (mA)

1611 TA04

U

Dimensions in inches (millimeters) unless otherwise noted.

PACKAGE DESCRIPTION

S5 Package

5-Lead Plastic SOT-23

(LTC DWG # 05-08-1633)

2.60 – 3.00

(0.102 – 0.118)

2.80 – 3.00

(0.110 – 0.118)

(NOTE 3)

1.50 – 1.75

(0.059 – 0.069)

0.00 – 0.15

(0.00 – 0.006)

0.90 – 1.45

(0.035 – 0.057)

0.35 – 0.55

(0.014 – 0.022)

0.35 – 0.50

(0.014 – 0.020)

FIVE PLACES (NOTE 2)

0.90 – 1.30

(0.035 – 0.051)

0.09 – 0.20

(0.004 – 0.008)

(NOTE 2)

0.95

(0.037)

REF

1.90

(0.074)

REF

NOTE:

S5 SOT-23 0599

1. DIMENSIONS ARE IN MILLIMETERS

2. DIMENSIONS ARE INCLUSIVE OF PLATING

3. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR

4. MOLD FLASH SHALL NOT EXCEED 0.254mm

5. PACKAGE EIAJ REFERENCE IS SC-74A (EIAJ)

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

3.3V/75mA from 1V, 600kHz Fixed Frequency

LT1307

Single Cell Micropower DC/DC with Low Battery Detector

Burst Mode^TMOperation DC/DC with Programmable Current Limit

2-Cell Micropower DC/DC with Low Battery Detector

LT1316

1.5V Minimum V , Precise Control of Peak Switch Current

IN

LT1317

3.3V/200mA from Two Cells, 600kHz Fixed Frequency

42V, 6A/3A Internal Switch, Negative Feedback Regulation

LT1370/LT1371 500kHz High Efficiency DC/DC Converter

LT1610

LT1613

LT1614

LT1615

LT1617

Single Cell Micropower DC/DC

3V/30mA from 1V, 1.7MHz Fixed Frequency, 30µA I

5V at 200mA from 3.3V Input

Q

1.4MHz SOT-23 Step-Up DC/DC Converter

Inverting Mode Switching Regulator with Low-Battery Detector

Micropower SOT-23 Step-Up DC/DC Converter

Micropower SOT-23 Inverting Regulator

–5V at 200mA from 5V Input in MSOP

20µA Quiescent Current, V

Up to 34V

OUT

V

Up to –34V, 20µA Quiescent Current

OUT

Burst Mode is a trademark of Linear Technology Corporation.

1611f LT/TP 0999 4K • PRINTED IN USA

12 ^{LinearTechnology Corporation}

1630 McCarthy Blvd., Milpitas, CA 95035-7417

●

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

LINEAR TECHNOLOGY CORPORATION 1998


型号：	LT1611CS5#TRMPBF
厂家：	Linear
描述：	LT1611 - Inverting 1.4MHz Switching Regulator in 5-Lead SOT-23; Package: SOT; Pins: 5; Temperature Range: 0°C to 70°C 稳压器开关
文件：	总12页 (文件大小：267K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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