LT1071CT#PBF_技术文档

LT1070/LT1071

5A and 2.5A High Efficiency

Switching Regulators

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FEATURES

DESCRIPTIO

The LT^®1070/LT1071 are monolithic high power switch-

ingregulators.Theycanbeoperatedinallstandardswitch-

ing configurations including buck, boost, flyback, for-

ward, inverting and “Cuk”. A high current, high efficiency

switch is included on the die along with all oscillator,

control and protection circuitry. Integration of all func-

tions allows the LT1070/LT1071 to be built in a standard

5-pin T0-220 power package. This makes it extremely

easy to use and provides “bust proof” operation similar to

that obtained with 3-pin linear regulators.

■

Wide Input Voltage Range: 3V to 60V

■

Low Quiescent Current: 6mA

■

Internal 5A Switch (2.5A for LT1071)

■

Very Few External Parts Required

■

Self Protected Against Overloads

Operates in Nearly All Switching Topologies

Shutdown Mode Draws Only 50µA Supply Current

Flyback Regulated Mode Has Fully Floating Outputs

Comes in Standard 5-Pin TO-220 Package

Can be Externally Synchronized (Consult Factory)

TheLT1070/LT1071operatewithsupplyvoltagesfrom3V

to 60V, and draw only 6mA quiescent current. They can

deliver load power up to 100W with no external power

devices. By utilizing current mode switching techniques,

they provide excellent AC and DC load and line regulation.

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APPLICATIO S

■

Logic Supply 5V at 10A

■

5V Logic to ±15V Op Amp Supply

■

Off-Line Converter Up to 200W

TheLT1070/LT1071havemanyuniquefeaturesnotfound

even on the vastly more difficult to use low power control

chipspresentlyavailable. Theyuseadaptiveantisatswitch

drive to allow very wide ranging load currents with no loss

in efficiency. An externally activated shutdown mode

reduces total supply current to 50µA typical for standby

operation. Totally isolated and regulated outputs can be

generatedbyusingtheoptional“flybackregulationmode”

built into the LT1070/LT1071, without the need for

optocouplers or extra transformer windings.

■

Battery Upconverter

■

Power Inverter (+ to –) or (– to +)

■

Fully Floating Multiple Outputs

■

For Lower Current Applications, See the LT1072

USER NOTE:

This data sheet is only intended to provide specifications, graphs and a general functional

description of the LT1070/LT1071. Application circuits are included to show the capability of the

LT1070/LT1071. A complete design manual (AN19) should be obtained to assist in developing new

designs. This manual contains a comprehensive discussion of both the LT1070 and the external

components used with it, as well as complete formulas for calculating the values of these

components. The manual can also be used for the LT1071 by factoring in the lower switch current

rating. A second Application Note, AN25, which details off-line applications is available.

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

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TYPICAL APPLICATIO

Maximum Output Power*

Boost Converter (5V to 12V)

100

L2

10µH

80

BOOST

BUCK/BOOST

O

5V

L1**

OUTPUT

FILTER

C3

V

= 30V

150µH

60

40

20

0

100µF

FLYBACK

D1

V

12V

1A

IN

V

SW

ISOLATED

+

R1

C2

1000µF

+

LT1070

10.7k

C3*

1%

100µF

BUCK/BOOST

= 5V

FB

V

O

GND

V

C

R2

1.24k

1%

0

10

20

30

40

50

R3

1k

C1

1µF

INPUT VOLTAGE (V)

1070/71 TA02

*ROUGH GUIDE ONLY. BUCK MODE P

= 5A • V

.

OUT

SPECIAL TOPOLOGIES DELIVER MORE POWER

*REQUIRED IF INPUT LEADS ≥ 2"

**PULSE ENGINEERING 92113

1070/71 TA01

**DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071

10701fe

1

LT1070/LT1071

W W

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ABSOLUTE MAXIMUM RATINGS

(Note 1)

Supply Voltage

Operating Junction Temperature Range

LT1070/LT1071 (Note 2) .................................... 40V

LT1070HV/LT1071HV (Note 2) .......................... 60V

Switch Output Voltage

LT1070/LT1071 .................................................. 65V

LT1070HV/LT1071HV ........................................ 75V

Feedback Pin Voltage (Transient, 1ms) ................ ±15V

Commercial (Operating) ....................... 0°C to 100°C

Commercial (Short Circuit)................... 0°C to 125°C

Industrial ......................................... –40°C to 125°C

Military (OBSOLETE) ................. –55°C to 150°C

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

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

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PACKAGE/ORDER INFORMATION

BOTTOM VIEW

ORDER PART

NUMBER

ORDER PART

NUMBER

V

C

SW

FRONT VIEW

LT1070CT

1

4

LT1070CK

2

5

4

3

2

1

V

IN

CASE

IS GND

LT1070HVCT

LT1070HVIT

LT1070IT

LT1070HVCK

LT1070HVMK

LT1070IK

SW

3

GND

FB

V

FB

IN

V

C

LT1071CT

LT1070MK

LT1071CK

LT1071HVCK

LT1071HVMK

LT1071MK

K PACKAGE

T PACKAGE

5-LEAD PLASTIC TO-220

4-LEAD TO-3 METAL CAN

LT1071HVCT

LT1071HVIT

LT1071IT

T_JMAX= 100°C, θ_JA= 35°C/ W, Q_JC= 2°C (LT1070C, I)

T_JMAX= 150°C, θ_JA= 35°C/ W, Q_JC= 2°C (LT1070M)

_JMAX= 100°C, θ_JA= 35°C/ W, Q_JC= 4°C (LT1071C, I)

T_JMAX= 150°C, θ_JA= 35°C/ W, Q_JC= 4°C (LT1071M)

T_JMAX= 100°C, θ_JA= 75°C/ W, Q_JC= 2°C (LT1070C, I)

T_JMAX= 100°C, θ_JA= 75°C/ W, Q_JC= 4°C (LT1071C)

T

OBSOLETE PACKAGE

Consider the T5 Package for Alternate Source

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

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

range, otherwise specifications are at T_A= 25°C. V_IN= 15V, V_C= 0.5V, V_FB= V_REF, output pin open unless otherwise specified.

SYMBOL

PARAMETER

CONDITIONS

Measured at Feedback Pin, V = 0.8V

MIN

TYP

MAX

UNITS

V

REF

Reference Voltage

1.224

1.214

1.244

1.264

1.274

V

C

●

I

Feedback Input Current

V

FB

= V

REF

350

4400

200

750

1100

nA

B

g

m

Error Amplifier Transconductance

Error Amplifier Source or Sink Current

Error Amplifier Clamp Voltage

∆I = ±25µA

C

3000

2400

6000

7000

µmho

V = 1.5V

C

150

120

350

400

µA

Hi Clamp, V = 1V

1.80

0.25

2.30

0.52

V

FB

Lo Clamp, V = 1.5V

0.38

FB

Reference Voltage Line Regulation

Error Amplifier Voltage Gain

Minimum Input Voltage

Supply Current

3V ≤ V ≤ V

, V = 0.8V

●

0.03

%/V

V/V

V

IN

MAX

C

A

0.9V ≤ V ≤ 1.4V

500

800

2.6

6

V

C

3.0

9

I

3V ≤ V ≤ V

, V = 0.6V

MAX

mA

Q

IN

C

Control Pin Threshold

Duty Cycle = 0

0.8

0.6

0.9

1.08

1.25

V

●

Normal/Flyback Threshold on Feedback Pin

0.4

0.45

0.54

V

10701fe

2

LT1070/LT1071

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

ELECTRICAL CHARACTERISTICS

range, otherwise specifications are at T_A= 25°C. V_IN= 15V, V_C= 0.5V, V_FB= V_REF, output pin open unless otherwise specified.

SYMBOL

PARAMETER

CONDITIONS

= 50µA

MIN

TYP

MAX

UNITS

V

Flyback Reference Voltage

I

15

14

16.3

17.6

18.0

V

FB

●

Change in Flyback Reference Voltage

0.05 ≤ I ≤ 1mA

4.5

6.8

0.01

300

8.5

0.03

650

V

%/V

FB

Flyback Reference Voltage Line Regulation

I

= 50µA, 3V ≤ V ≤ V

(Note 3)

FB

IN

MAX

Flyback Amplifier Transconductance (g )

∆I = ±10µA

C

150

µmho

m

Flyback Amplifier Source and Sink Current

V = 0.6V, I = 50µA (Source)

●

15

25

32

40

70

µA

C

FB

V = 0.6V, I = 50µA (Sink)

C

FB

B

V

Output Switch Breakdown Voltage

3V ≤ V ≤ V

(LT1070/LT1071)

(LT1070HV/LT1071HV)

, I = 1.5mA

V

IN

MAX SW

●

65

75

90

V

Output Switch “On” Resistance (Note 4)

LT1070

LT1071

●

0.15

0.30

0.24

0.50

Ω

SAT

Control Voltage to Switch Current

Transconductance

LT1070

LT1071

8

4

A/V

I

Switch Current Limit (LT1070)

Duty Cycle ≤ 50%, T ≥ 25°C

●

5

4

10

11

10

A

LIM

J

Duty Cycle ≤ 50%, T < 25°C

J

Duty Cycle = 80% (Note 5)

Switch Current Limit (LT1071)

Duty Cycle ≤ 50%, T ≥ 25°C

●

2.5

2.0

5.0

5.5

5.0

A

J

Duty Cycle ≤ 50%, T < 25°C

J

Duty Cycle = 80% (Note 5)

∆I

Supply Current Increase During

Switch “On” Time

25

40

35

mA/A

IN

∆I

SW

f

Switching Frequency

35

33

45

47

kHz

●

DC (Max)

Maximum Switch Duty Cycle

Flyback Sense Delay Time

90

92

1.5

97

%

µs

µA

Shutdown Mode Supply Current

Shutdown Mode Threshold Voltage

3V ≤ V ≤ V

, V = 0.05V

C

100

150

250

IN

MAX

3V ≤ V ≤ V

100

50

250

300

mV

IN

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

a device may be impaired.

t = Minimum “on” time of LT1070/LT1071 in current limit, ≈1µs

f = Operating frequency (40kHz)

V = Forward voltage of external catch diode at I

F

LIMIT

Note 2: Minimum switch “on” time for the LT1070/LT1071 in current limit is

≈1µs. This limits the maximum input voltage during short-circuit conditions,

inthebuckandinvertingmodesonly,to≈35V.Normal(unshorted)conditions

are not affected. Mask changes are being implemented which will reduce

minimum“on”timeto≤1µs, increasingmaximumshort-circuitinputvoltage

above 40V. If the present LT1070/LT1071 (contact factory for package date

code) is being operated in the buck or inverting mode at high input voltages

and short-circuit conditions are expected, a resistor must be placed in series

with the inductor, as follows:

I

= Current limit of LT1070 (≈8A), LT1071 (≈4A)

LIMIT

R = Internal series resistance of inductor

L

Note 3: V

= 55V for LT1070HV and LT1071HV to avoid switch

MAX

breakdown.

Note 4: Measured with V in hi clamp, V = 0.8V. I = 4A for LT1070

C

FB

SW

and 2A for LT1071.

Note 5: For duty cycles (DC) between 50% and 80%, minimum

guaranteed switch current is given by I = 3.33 (2 – DC) for the

LIM

The value of the resistor is given by:

LT1070 and I = 1.67 (2 – DC) for the LT1071.

LIM

t • f • V – V

IN

F

R =

– R

L

I

LIMIT

10701fe

3

LT1070/LT1071

TYPICAL PERFORMANCE CHARACTERISTICS

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Switch Current Limit vs Duty Cycle

Maximum Duty Cycle

Flyback Blanking Time

16

14

12

10

8

96

95

2.2

2.0

FOR LT1071, DIVIDE

VERTICAL SCALE BY 2

94

1.8

–55°C

125°C

25°C

93

92

1.6

1.4

6

4

91

90

1.2

1.0

2

0

10 20 30 40 50 60 70 80 90 100

–75 –50 –25

0

25 50 75 100 125 150

–75 –50 –25

0

25 50 75 100 125 150

DUTY CYCLE (%)

JUNCTION TEMPERATURE (°C)

1070/71 G01

1070/71 G02

1070/71 G03

Minimum Input Voltage

Switch Saturation Voltage

2.9

2.8

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

0

23

22

21

20

19

18

17

16

15

FOR LT1071, DIVIDE

CURRENT BY 2

SWITCH CURRENT = 5A

150°C

R

= 500Ω

FEEDBACK

R

100°C

2.7

25°C

–55°C

= 1k

2.6

2.5

FEEDBACK

SWITCH CURRENT = 0A

R

= 10k

FEEDBACK

2.4

2.3

4

5

0

1

2

3

6

7

8

–75 –50 –25

0

25 50 75 100 125 150

–75 –50 –25

0

25 50 75 100 125 150

SWITCH CURRENT (A)

TEMPERATURE (°C)

1070/71 G05

1070/71 G06

1070/71 G04

Feedback Bias Current

vs Temperature

Reference Voltage

vs Temperature

Line Regulation

5

4

1.250

1.248

1.246

1.244

1.242

1.240

1.238

1.236

1.234

42

41

40

39

38

37

36

35

34

800

700

600

500

400

300

200

100

0

SWITCHING

FREQUENCY

T = 150°C

3

2

1

0

J

T = 25°C

J

REFERENCE

V0LTAGE

T = –55°C

J

–1

–2

–3

–4

–5

–75 –50 –25

0

25 50 75 100 125 150

–75 –50 –25

0

25 50 75 100 125 150

0

10

30

40

50

60

20

TEMPERATURE (°C)

INPUT VOLTAGE (V)

1070/71 G08

1070/71 G09

1070/71 G07

10701fe

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LT1070/LT1071

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TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Supply Voltage

(Shutdown Mode)

Driver Current* vs Switch Current

Supply Current vs Input Voltage*

160

140

120

100

80

16

15

14

13

12

11

10

9

160

140

120

100

T = 25°C

J

T = 25°C

J

90% DUTY CYCLE

I

≤ 10mA

SWITCH

V

C

= 50mV

80

60

T = –55°C

J

50% DUTY CYCLE

60

T ≥ 25°C

J

40

20

0

10% DUTY CYCLE

0% DUTY CYCLE

8

20

V

= 0V

30

C

7

0

6

10

20

40

0

50

60

0

1

2

3

4

5

0

10

30

40

50

60

20

SUPPLY VOLTAGE (V)

SWITCH CURRENT (A)

INPUT VOLTAGE (V)

1070/71 G10

1070/71 G11

1070/71 G12

*UNDER VERY LOW OUTPUT CURRENT

CONDITIONS, DUTY CYCLE FOR MOST

CIRCUITS WILL APPROACH 10% OR LESS

*AVERAGE LT1070 POWER SUPPLY CURRENT IS

FOUND BY MULTIPLYING DRIVER CURRENT BY

DUTY CYCLE, THEN ADDING QUIESCENT CURRENT

Normal/Flyback Mode Threshold

on Feedback Pin

Shutdown Mode Supply Current

Error Amplifier Transconductance

500

–24

–22

–20

–18

–16

–14

–12

–10

–8

200

180

160

140

120

100

80

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

∆I (V PIN)

C

g

m

=

490

480

470

460

450

440

430

420

410

400

∆V (FB PIN)

FEEDBACK PIN VOLTAGE

(AT THRESHOLD)

T = 150°C

J

60

–55°C ≤ T ≤ 125°C

FEEDBACK PIN CURRENT

(AT THRESHOLD)

J

40

–6

20

0

–4

150

–75 –50 –25

0

25 50 75 100 125 150

0

10 20 30 40 50 60 70 80 90 100

PIN VOLTAGE (mV)

–50

50

100 125

–25

0

25

75

V

TEMPERATURE (°C)

C

1070/71 G14

1070/71 G13

Idle Supply Current

vs Temperature

Shutdown Thresholds

Feedback Pin Clamp Voltage

500

450

400

350

300

250

200

150

100

50

11

400

350

300

250

200

150

100

50

–400

–350

–300

–250

–200

–150

–100

–50

V

= 0.6V

C

10

9

CURRENT

(OUT OF V PIN)

C

–55°C

25°C

8

V

= 60V

= 3V

SUPPLY

7

6

150°C

V

VOLTAGE

SUPPLY

5

4

3

V

C

VOLTAGE IS REDUCED UNTIL

REGULATOR CURRENT DROPS

2

BELOW 300µA

0

1

0

–75 –50 –25

0

25 50 75 100 125 150

–75 –50 –25

0

25 50 75 100 125 150

0

0.1 0.2 0.3 0.4 0.5 0.6 0.7

0.8

0.9 1.0

TEMPERATURE (°C)

FEEDBACK CURRENT (mA)

1070/71 G16

1070/71 G14

1070/71 G18

10701fe

5

LT1070/LT1071

TYPICAL PERFORMANCE CHARACTERISTICS

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Transconductance of Error

Amplifier

Switch “Off” Characteristics

V_CPin Characteristics

300

200

7000

6000

5000

4000

3000

2000

1000

0

–30

0

1000

900

800

700

600

500

400

300

200

100

0

T = 25°C

J

θ

30

V

= 1.5V

FB

100

(CURRENT INTO

g

m

60

V

PIN)

C

0

90

V

=

SUPPLY

–100

–200

–300

–400

V

= 0.8V

FB

120

150

180

210

(CURRENT OUT OF V PIN)

C

3V 15V

40V 55V

–1000

0

10 20 30 40 50 60 70 80 90 100

SWITCH VOLTAGE (V)

0

0.5

1.0

1.5

2.0

2.5

1k

10k

100k

1M

10M

FREQUENCY (Hz)

V

PIN VOLTAGE (V)

C

1070/71 G21

1070/71 G19

1070/71 G20

W

BLOCK DIAGRAM

16V

SWITCH

OUT

V

IN

2.3V

REG

FLYBACK

ERROR

AMP

40kHz

OSC

5A, 75V

SWITCH

LOGIC

COMP

DRIVER

MODE

SELECT

ANTISAT

–

FB

ERROR

AMP

V

C

+

CURRENT

AMP

0.02Ω

(0.04Ω LT1071)

SHUTDOWN

CIRCUIT

–

1.24V

REF

GAIN ≈ 6

0.15V

1070/71 BD

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OPERATION

voltage is obtained by using the output of a voltage

sensing error amplifier to set current trip level. This

techniquehasseveraladvantages. First, ithasimmediate

response to input voltage variations, unlike ordinary

switchers which have notoriously poor line transient

The LT1070/LT1071 is a current mode switcher. This

means that switch duty cycle is directly controlled by

switchcurrentratherthanbyoutputvoltage.Referringto

the Block Diagram, the switch is turned “on” at the start

of each oscillator cycle. It is turned “off” when switch

current reaches a predetermined level. Control of output

response. Second, it reduces the 90° phase shift at

10701fe

6

LT1070/LT1071

U

OPERATION

midfrequencies in the energy storage inductor. This

greatly simplifies closed-loop frequency compensation

under widely varying input voltage or output load condi-

tions. Finally, it allows simple pulse-by-pulse current

limiting to provide maximum switch protection under

output overload or short-circuit conditions. A low drop-

out internal regulator provides a 2.3V supply for all

internal circuitry of the LT1070/LT1071. This low drop-

out design allows input voltage to vary from 3V to 60V

with virtually no change in device performance. A 40kHz

oscillator is the basic clock for all internal timing. It turns

“on” the output switch via the logic and driver circuitry.

Special adaptive antisat circuitry detects onset of satura-

tion in the power switch and adjusts driver current

instantaneously to limit switch saturation. This mini-

mizes driver dissipation and provides very rapid turn-off

of the switch.

transformercoupledflybacktopologyregulator.Byregu-

lating the amplitude of the flyback pulse, the output

voltage can be regulated with no direct connection be-

tween input and output. The output is fully floating up to

the breakdown voltage of the transformer windings.

Multiple floating outputs are easily obtained with addi-

tionalwindings.AspecialdelaynetworkinsidetheLT1070/

LT1071 ignores the leakage inductance spike at the

leading edge of the flyback pulse to improve output

regulation.

The error signal developed at the comparator input is

brought out externally. This pin (V_C) has four different

functions. Itisusedforfrequencycompensation, current

limit adjustment, soft starting and total regulator shut-

down. During normal regulator operation this pin sits at

a voltage between 0.9V (low output current) and 2.0V

(high output current). The error amplifiers are current

output (g_m) types, so this voltage can be externally

clamped for adjusting current limit. Likewise, a capacitor

coupled external clamp will provide soft start. Switch

duty cycle goes to zero if the V_Cpin is pulled to ground

through a diode, placing the LT1070/LT1071 in an idle

mode. Pulling the V_Cpin below 0.15V causes total

regulator shutdown, with only 50µA supply current for

shutdown circuitry biasing. See AN19 for full application

details.

A 1.2V bandgap reference biases the positive input of the

error amplifier. The negative input is brought out for

output voltage sensing. This feedback pin has a second

function; when pulled low with an external resistor, it

programs the LT1070/LT1071 to disconnect the main

error amplifier output and connects the output of the

flyback amplifier to the comparator input. The LT1070/

LT1071 will then regulate the value of the flyback pulse

with respect to the supply voltage. This flyback pulse is

directly proportional to output voltage in the traditional

U

TYPICAL APPLICATIONS ^{(Note that maximum output currents are divided by 2 for the LT1071)}

Driving High Voltage NPN

C1

Driving High Voltage FET (for Off-Line

Applications, See AN25)

D2

D

S

R2**

D1

G

Q1

R1*

Q1

D1

V

IN

V

SW

V

IN

V

SW

LT1070/LT1071

GND

*SETS I

B(ON)

LT1070/LT1071

GND

+

10V

TO

20V

**SETS I

B(OFF)

1070 1 TA03

1070/7^/71 TA03

1070/71 TA16

10701fe

7

LT1070/LT1071

TYPICAL APPLICATIONS

U

(Note that maximum output currents are divided by 2 for the LT1071)

Negative Buck Converter

+

C2

1000µF

D1

LOAD

L1**

200µH

R1

4.64k

V

IN

–5.2V

4.5A

V

SW

+

Q1

2N3906

C3

100µF

LT1070

OPTIONAL INPUT

FILTER

FB

C1

GND

V

C

L3

OPTIONAL

OUTPUT

FILTER

+

C4

200µF

R2

1.24k

R3

L2

4µH

V

IN

–20V

*REQUIRED IF INPUT LEADS ≥ 2"

**PULSE ENGINEERING 92113

1070/71 TA12

Positive Buck Converter

V

IN

D3

L2

4µH

V

IN

OPTIONAL

OUTPUT

FILTER

C5

200µF

V

SW

+

C3

2.2µF

LT1070

D2

R1

+

1N914

C5*

100µF

3.74k

FB

GND

V

C

+

R2

C2

1µF

R3

470Ω

C1

1µF

R4

10Ω

1.24k

L1**

100µH

r

5V

4.5A

+

100mA

C4

1000µF

D1

MINIMUM

1070/71 TA14

*REQUIRED IF INPUT LEADS ≥2"

**PULSE ENGINEERING 92112

Negative Current Boosted Buck Converter

+

MINIMUM

LOAD = 10mA

R1

C1

–V

5V

OUT

T1

1:N

10A

R5

C3

•

R4

12k

D1

V – 0.6V

OUT

1mA

Q1

2N3906

R1 =

V

IN

•

V

SW

+

LT1070

FB

GND

V

C

R2

R3

C2

1.24k

1070/71 TA13

–V

IN

10701fe

8

LT1070/LT1071

U

(Note that maximum output currents are divided by 2 for the LT1071)

TYPICAL APPLICATIONS

Positive Current Boosted Buck Converter

V

IN

28V

470Ω

2W

R6

470Ω

C3

0.47µF

•

C6

0.002µF

D2

•

V

IN

1:N

V

SW

N ≈ 0.25

LT1070

R2

1k

R7

1.24k

D1

FB

GND

V

C

V

IN

7

–

+

2

3

R3

680Ω

+

V

6

R5

5k

–

LM308

COMP

V

+

C5*

100µF

4

C1

0.33µF

8

R4

1.24k

200pF

V

OUT

5V

R1

5k

10A

+

C2

5000µF

*REQUIRED IF INPUT LEADS ≥ 2"

1070/71 TA19

Positive to Negative Buck/Boost Converter

Negative to Positive Buck/Boost Converter

†

R5

TO AVOID START-UP

†

D3

L2

470Ω

1W

PROBLEMS FOR INPUT

VOLTAGES BELOW 10V,

CONNECT ANODE OF D3

1N4001

OPTIONAL

V

IN

10V TO 30V

C3

L1**

OUTPUT

150µH

TO V AND REMOVE R5.

IN

C5*

100µF

FILTER

C1 MAY BE REDUCED FOR

V

IN

V

SW

LOWER OUTPUT CURRENTS.

D1

V

12V

2A

OUT

C1 ≈ (500µF)(I ) FOR 5V

OUT

V

IN

+

V

SW

FB

C4

OUTPUTS, REDUCE R3 TO

1.5k, INCREASE C2 TO 0.3µF

AND REDUCE R6 TO 100Ω.

+

LT1070

5µF

R1

11.3k

C2

1000µF

D2

1N914

+

R1

R4

47Ω

C4*

100µF

LT1070

10.7k

FB

Q1

GND

V

C

L3

+

†

R3

5k

C1

0.1µF

R2

C3

C1

GND

V

C

R6

470Ω

1.24k

2µF 1000µF

OPTIONAL

INPUT

FILTER

R3

2.2k

R2

1.24k

D1

V

–12V

2A

OUT

C1

0.22µF

1070/71 TA09

V

IN

–12V

L1**

200µH

1070/71 TA05

*REQUIRED IF INPUT LEADS ≥ 2"

**PULSE ENGINEERING 92113

*REQUIRED IF INPUT LEADS ≥ 2"

**PULSE ENGINEERING 92113

10701fe

9

LT1070/LT1071

TYPICAL APPLICATIONS ^{(Note that maximum output currents are divided by 2 for the LT1071)}

U

Current Boosted Boost Converter

Voltage Boosted Boost Converter

R4

C3

680Ω

R4

C3

0.68µF

D1

I

V

28V

4A

OUT

1W

TOTAL

INDUCTANCE = 4mH

N

D2

1

L1

N = 5

V

IN

INTERLEAVE PRIMARY

AND SECONDARY FOR

LOW LEAKAGE

IN

V

SW

FB

R1

27k

+

V

IN

15V

IN

INDUCTANCE

16V TO 24V

LT1070

D1

+

R1

98k

C1

V

OUT

100V

FB

GND

V

GND

V

C

300mA

+

R3

R2

1.24k

R2

1.24k

C1

200µF

R3

C2

10k

C2

0.047µF

1070/71 TA10

1070/71 TA11

Negative Input/Negative Output Flyback Converter

Negative Boost Regulator

•

D2

C3

R6

R2

5k

R3

1k

V

•

IN

V

+

SW

T1

1:N

V

IN

Q1

2N3906

V

SW

C1

R

+

O

R1*

R1

27k

C1

1000µF

LT1070

(MINIMUM

+

LT1070/LT1071

LOAD)

C4*

470µF

+

–V

OUT

C3

FB

R3

3.3k

C2

GND

V

10µF

C

FB

V

– 1.6V

OUT

200µA

GND

V

C

*R1 =

R2

1.24k

R4

R5

C2

L1

200µH

1.24k

D1

V

–28V

1A

0.22µF

OUT

V

IN

1070/71 TA17

–V

IN

–15V

*REQUIRED IF INPUT LEADS ≥ 2"

1070/71 TA15

External Current Limit

V

IN

V

SW

V

X

LT1070/LT1071

= 2V

LT1070/LT1071

R2

+

V

IN

FB

GND

V

C

GND

V

C

D1

R1

500Ω

R1

1k

R2

C2

Q1

C1

1000pF

1070/71 TA04

R

S

NOTE THAT THE LT1070/LT1071

GND PIN IS NO LONGER COMMON

–

TO V

1070/71 TA06

IN

10701fe

10

LT1070/LT1071

U

TYPICAL APPLICATIONS ^{(Note that maximum output currents are divided by 2 for the LT1071)}

Flyback Converter

CLAMP TURN-ON

SPIKE

V

SNUB

L2

10µH

V

+ V

N

OUT

F

a

PRIMARY FLYBACK VOLTAGE =

V

IN

b

LT1070/LT1071 SWITCH VOLTAGE

AREA “a” = AREA “b” TO MAINTAIN

ZERO DC VOLTS ACROSS PRIMARY

C4

OPTIONAL

FILTER

0V

200µF

V

+ V

F

OUT

D1

V

OUT

V

IN

SECONDARY VOLTAGE

)

c

5V

6A

(N)(V

IN

20V TO 30V

1 N

AREA “c” = AREA “d” TO MAINTAIN

ZERO DC VOLTS ACROSS SECONDARY

0V

C3

0.47µF

R4

•

d

+

C1

2000µF

∆I

D2

I

•

PRI

V

IN

V

SW

PRIMARY CURRENT

N = 1/3

0

R1

+

C4*

100µF

I

N

PRI

3.74k

LT1070

SECONDARY CURRENT

LT1070 SWITCH CURRENT

FB

I

PRI

GND

V

C

R2

1.24k

R3

1.5k

C2

I

PRI

0.15µF

SNUBBER DIODE CURRENT

1070/71 TA08

*REQUIRED IF INPUT LEADS ≥ 2"

(I )(L )

PRI

L

t =

V

SNUB

U

PACKAGE DESCRIPTION

K Package

4-Lead TO-3 Metal Can

(Reference LTC DWG # 05-08-1311)

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

0.760 – 0.775

(19.30 – 19.69)

0.320 – 0.350

(8.13 – 8.89)

0.060 – 0.135

(1.524 – 3.429)

0.165 – 0.180

(4.191 – 4.572)

0.147 – 0.155

(3.734 – 3.937)

DIA

0.390 – 0.415

(9.906 – 10.541)

0.045 – 0.055

(1.143 – 1.397)

0.230 – 0.270

(5.842 – 6.858)

0.420 – 0.480

(10.67 – 12.19)

0.570 – 0.620

(14.478 – 15.748)

0.620

(15.75)

TYP

0.460 – 0.500

(11.684 – 12.700)

0.038 – 0.043

(0.965 – 1.09)

0.330 – 0.370

(8.382 – 9.398)

0.700 – 0.728

(17.78 – 18.491)

1.177 – 1.197

(29.90 – 30.40)

0.655 – 0.675

(16.64 – 19.05)

0.095 – 0.115

(2.413 – 2.921)

0.470 TP

P.C.D.

SEATING PLANE

0.152 – 0.202

0.151 – 0.161

(3.84 – 4.09)

DIA 2 PLC

0.155 – 0.195*

(3.937 – 4.953)

(3.861 – 5.131)

0.260 – 0.320

(6.60 – 8.13)

0.013 – 0.023

(0.330 – 0.584)

0.167 – 0.177

(4.24 – 4.49)

R

0.067

BSC

0.135 – 0.165

(3.429 – 4.191)

0.028 – 0.038

(0.711 – 0.965)

T5 (TO-220) 0399

(1.70)

0.490 – 0.510

(12.45 – 12.95)

R

* MEASURED AT THE SEATING PLANE

72°

18°

K4(TO-3) 1098

OBSOLETE PACKAGE

10701fe

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

LT1070/LT1071

TYPICAL APPLICATIONS

U

(Note that maximum output currents are divided by 2 for the LT1071)

Totally Isolated Converter

OPTIONAL

OUTPUT FILTER

L1

D1

10µF

15V

COM

–15V

1:N

+

R4

1.5k

C3

0.47µF

C1

C5

N

•

500µF

200µF

L2

10µF

N

C4

500µF

C6

200µF

V

IN

•

V

SW

+

N = 0.875 = 7:8

FOR V = 15V

+

V

IN

5V

C5*

100µF

OUT

LT1070/LT1071

≈16V

SWITCH VOLTAGE

FB

V

GND

V

C

IN

t

ON

OFF

500Ω

0V

V

F

R2

C2

0.01µF

V

(DIODE FORWARD VOLTAGE)

SECONDARY VOLTAGE

1070/71 TA07

5k

OUT

0V

*REQUIRED IF INPUT LEADS ≥ 2"

(N)(V

)

IN

Forward Converter

L1

70µH

D1

V

OUT

5V

6A

T1

I

M

N

•

R4

C2

+

C1

2000µF

D2

D3

•

V

IN

V

SW

V

R1

3.74k

IN

LT1070

D4

20V TO 30V

FB

GND

V

C

Q1

R2

1.24k

R6

330Ω

R3

C3

R5

1Ω

C4

1070/71 TA18

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

LT1074/LT1076

High Voltage Switching Regulators

40V Input (60V for HV Versions), 100kHz, 5A and 2A

LT1170/LT1171/

LT1172

100kHz High Efficiency Switching Regulators

40V Input (65V for HV Versions), 5A/2.5A/1.25A Internal Switch

LT1370/LT1371

LT1374/LT1376

LT1765

500kHz High Efficiency Switching Regulators

100kHz High Efficiency Switching Regulators

1.25MHz, 3A, Step-Down Regulator

35V, 6A/3A Internal Switch

25V Input, 4.5A/1.5A Internal Switch

25V Input, TSSOP-16E, SO8 Package

10701fe

LT/CPI 0202 1.5K REV E • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

12

●

LINEAR TECHNOLOGY CORPORATION 1989

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


型号：	LT1071CT#PBF
厂家：	Linear
描述：	LT1071 - 5A and 2.5A High Efficiency Switching Regulators; Package: TO-220; Pins: 5; Temperature Range: 0°C to 70°C 局域网开关
文件：	总12页 (文件大小：221K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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