ANALOG DEVICES LT1071CTPBF Datasheet

FEATURES

LT1070/LT1071

5A and 2.5A High Efficiency

Switching Regulators

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DESCRIPTIO

■

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)

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APPLICATIO S

■

Logic Supply 5V at 10A

■

5V Logic to ±15V Op Amp Supply

■

Off-Line Converter Up to 200W

■

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.

The LT®1070/LT1071 are monolithic high power switching regulators. They can be operated in all standard switching configurations including buck, boost, flyback, forward, 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 functions 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.

The LT1070/LT1071 operate with supply voltages from 3V 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.

The LT1070/LT1071 have many unique features not found even on the vastly more difficult to use low power control chips presently available. They use adaptive antisat switch 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 generated by using the optional “flyback regulation mode” built into the LT1070/LT1071, without the need for optocouplers or extra transformer windings.

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

TYPICAL APPLICATIO

Boost Converter (5V to 12V)

5V

+

C3*

100µF

GND

***REQUIRED IF INPUT LEADS ≥ 2"

PULSE ENGINEERING 92113

V

IN

LT1070

V

C

L1**

150µH

V

SW

FB

R3 1k

C1 1µF

OUTPUT

D1

10µH

FILTER

+

U

L2

C2 1000µF

C3 100µF

R1

10.7k 1%

R2

1.24k 1%

1070/71 TA01

12V 1A

Maximum Output Power*

100

80

60

40

POWER (W)**

20

*

**

BOOST

0

10

0

ROUGH GUIDE ONLY. BUCK MODE P SPECIAL TOPOLOGIES DELIVER MORE POWER

DIVIDE VERTICAL POWER SCALE BY 2 FOR LT1071

INPUT VOLTAGE (V)

ISOLATED

BUCK/BOOST

20

BUCK/BOOST V

= 5V

V

O

30

= 30V

O

FLYBACK

OUT

40

1070/71 TA02

= 5A • V

50

.

OUT

10701fe

1

LT1070/LT1071

WW

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ABSOLUTE MAXIMUM RATINGS

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(Note 1)

Supply Voltage

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

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PACKAGE/ORDER INFORMATION

BOTTOM VIEW

V

SW

1

4

V

IN

K PACKAGE

4-LEAD TO-3 METAL CAN

T

= 100°C, θJA = 35°C/ W, QJC = 2°C (LT1070C, I)

JMAX

= 150°C, θJA = 35°C/ W, QJC = 2°C (LT1070M)

T

JMAX

T

= 100°C, θJA = 35°C/ W, QJC = 4°C (LT1071C, I)

JMAX

= 150°C, θJA = 35°C/ W, QJC = 4°C (LT1071M)

T

JMAX

2

3

V

FB

C

CASE IS GND

OBSOLETE PACKAGE

Consider the T5 Package for Alternate Source

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

ORDER PART

NUMBER

LT1070CK LT1070HVCK LT1070HVMK LT1070IK LT1070MK LT1071CK LT1071HVCK LT1071HVMK LT1071MK

Operating Junction Temperature Range

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

ORDER PART

NUMBER

FRONT VIEW

5 4 3 2 1

T PACKAGE

5-LEAD PLASTIC TO-220

T

= 100°C, θJA = 75°C/ W, QJC = 2°C (LT1070C, I)

JMAX

= 100°C, θJA = 75°C/ W, QJC = 4°C (LT1071C)

T

JMAX

V V GND FB V

IN SW

C

LT1070CT LT1070HVCT LT1070HVIT LT1070IT LT1071CT LT1071HVCT LT1071HVIT LT1071IT

ELECTRICAL CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

REF

I

B

g

m

A

V

I

Q

Reference Voltage Measured at Feedback Pin, VC = 0.8V 1.224 1.244 1.264 V

Feedback Input Current VFB = V

Error Amplifier Transconductance ∆IC = ±25µA 3000 4400 6000 µmho

Error Amplifier Source or Sink Current VC = 1.5V 150 200 350 µA

Error Amplifier Clamp Voltage Hi Clamp, VFB = 1V 1.80 2.30 V

Reference Voltage Line Regulation 3V ≤ VIN ≤ V Error Amplifier Voltage Gain 0.9V ≤ VC ≤ 1.4V 500 800 V/V Minimum Input Voltage ● 2.6 3.0 V Supply Current 3V ≤ VIN ≤ V Control Pin Threshold Duty Cycle = 0 0.8 0.9 1.08 V

Normal/Flyback Threshold on Feedback Pin 0.4 0.45 0.54 V

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

, output pin open unless otherwise specified.

REF

● 1.214 1.244 1.274 V

REF

Lo Clamp, V

● 1100 nA

● 2400 7000 µmho

● 120 400 µA

= 1.5V 0.25 0.38 0.52 V

FB

, VC = 0.8V ● 0.03 %/V

MAX

, VC = 0.6V 6 9 mA

MAX

● 0.6 1.25 V

350 750 nA

10701fe

2

LT1070/LT1071

ELECTRICAL CHARACTERISTICS

range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = V

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

, output pin open unless otherwise specified.

REF

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

FB

Flyback Reference Voltage IFB = 50µA 15 16.3 17.6 V

● 14 18.0 V

Change in Flyback Reference Voltage 0.05 ≤ IFB ≤ 1mA 4.5 6.8 8.5 V Flyback Reference Voltage Line Regulation IFB = 50µA, 3V ≤ VIN ≤ V

(Note 3) 0.01 0.03 %/V

MAX

Flyback Amplifier Transconductance (gm) ∆IC = ±10µA 150 300 650 µmho Flyback Amplifier Source and Sink Current VC = 0.6V, IFB = 50µA (Source) ● 15 32 70 µA

V

= 0.6V, IFB = 50µA (Sink) ● 25 40 70 µA

C

B

V

SAT

Output Switch Breakdown Voltage 3V ≤ VIN ≤ V

(LT1070/LT1071) (LT1070HV/LT1071HV)

MAX, ISW

= 1.5mA

● 65 90 V

● 75 90 V

Output Switch “On” Resistance (Note 4) LT1070 ● 0.15 0.24 Ω

LT1071

● 0.30 0.50 Ω

Control Voltage to Switch Current LT1070 8 A/V Transconductance LT1071 4 A/V

I

LIM

Switch Current Limit (LT1070) Duty Cycle ≤ 50%, TJ ≥ 25°C ● 510A

Duty Cycle ≤ 50%, T Duty Cycle = 80% (Note 5)

< 25°C ● 511A

J

● 410A

Switch Current Limit (LT1071) Duty Cycle ≤ 50%, TJ ≥ 25°C ● 2.5 5.0 A

∆I ∆I

SW

Duty Cycle ≤ 50%, T Duty Cycle = 80% (Note 5)

IN

Supply Current Increase During 25 35 mA/A Switch “On” Time

< 25°C ● 2.5 5.5 A

J

● 2.0 5.0 A

f Switching Frequency 35 40 45 kHz

● 33 47 kHz

DC (Max) Maximum Switch Duty Cycle 90 92 97 %

Flyback Sense Delay Time 1.5 µs Shutdown Mode Supply Current 3V ≤ VIN ≤ V Shutdown Mode Threshold Voltage 3V ≤ VIN ≤ V

, VC = 0.05V 100 250 µA

MAX

100 150 250 mV

● 50 300 mV

Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.

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,

in the buck and inverting modes only

, to ≈35V. Normal (unshorted) conditions

are not affected. Mask changes are being implemented which will reduce minimum “on” time to ≤1µs, increasing maximum short-circuit input voltage 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:

The value of the resistor is given by:

t • f • VIN – V

R = – R

I

LIMIT

F

L

t = Minimum “on” time of LT1070/LT1071 in current limit, ≈1µs f = Operating frequency (40kHz) VF = Forward voltage of external catch diode at I 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

LIMIT

breakdown. Note 4: Measured with V

in hi clamp, VFB = 0.8V. ISW = 4A for LT1070

C

and 2A for LT1071. Note 5: For duty cycles (DC) between 50% and 80%, minimum

guaranteed switch current is given by I LT1070 and I

= 1.67 (2 – DC) for the LT1071.

LIM

= 3.33 (2 – DC) for the

LIM

10701fe

3

LT1070/LT1071

JUNCTION TEMPERATURE (°C)

–75

1.0

TIME (µs)

1.2

1.6

1.8

2.0

–25

25

50 150

1070/71 G03

1.4

–50 0

75

100

125

2.2

UW

TYPICAL PERFORMANCE CHARACTERISTICS

Switch Current Limit vs Duty Cycle

16

FOR LT1071, DIVIDE VERTICAL SCALE BY 2

14

12

10

8

6

SWITCH CURRENT (A)

4

2

0

–55°C

125°C

20 40 60 1007010 30 50 90

0

DUTY CYCLE (%)

25°C

Minimum Input Voltage

2.9

2.8

2.7

2.6

2.5

MINIMUM INPUT VOLTAGE (V)

2.4

2.3 –75

SWITCH CURRENT = 5A

SWITCH CURRENT = 0A

–50 0

–25

25

TEMPERATURE (°C)

50 150

75

100

80

1070/71 G01

125

1070/71 G04

Maximum Duty Cycle

96

95

94

93

92

DUTY CYCLE (%)

91

90

–50 0

–25

–75

JUNCTION TEMPERATURE (°C)

50 150

25

Switch Saturation Voltage

1.6 FOR LT1071, DIVIDE

CURRENT BY 2

1.4

1.2

1.0

0.8

0.6

0.4

SWITCH SATURATION VOLTAGE (V)

0.2

0

1

2

100°C

4

3

SWITCH CURRENT (A)

Flyback Blanking Time

100

125

75

1070/71 G02

23

150°C

25°C

–55°C

5

6

7

1070/71 G05

8

22

21

20

19

18

FLYBACK VOLTAGE (V)

17

16

15

–25 25 75–50 1500 50 100

–75

R

TEMPERATURE (°C)

FEEDBACK

R

FEEDBACK

R

FEEDBACK

= 500Ω

= 1k

= 10k

125

1070/71 G06

Line Regulation

5 4

3 2 1 0

–1 –2

–3

REFERENCE VOLTAGE CHANGE (mV)

–4 –5

0

10

4

TJ = 25°C

30 40

20

INPUT VOLTAGE (V)

TJ = 150°C

TJ = –55°C

50

1070/71 G07

Reference Voltage vs Temperature

1.250

1.248

1.246

1.244

1.242

1.240

REFERENCE VOLTAGE (V)

1.238

1.236

1.234

60

–75

SWITCHING

FREQUENCY

REFERENCE

V0LTAGE

–25 25 75–50 1500 50 100

TEMPERATURE (°C)

125

1070/71 G08

Feedback Bias Current vs Temperature

42

41

40

39

38

37

36

35

34

800

700

SWITCHING FREQUENCY (kHz)

600

500

400

300

200

FEEDBACK BIAS CURRENT (nA)

100

0

–75

–25 25 75–50 1500 50 100

TEMPERATURE (°C)

125

1070/71 G09

10701fe

UW

FEEDBACK CURRENT (mA)

0

FEEDBACK VOLTAGE (mV)

300

400

500

0.8

1070/71 G18

200

100

250

350

450

150

50

0

0.2

0.4

0.6

0.1 0.9

0.3

0.5

0.7

1.0

–55°C

25°C

150°C

TEMPERATURE (°C)

–75

TRANSCONDUCTANCE (µmho)

3000

4000

5000

125

1070/71 G14

2000

1000

2500

3500

4500

1500

500

0

–25

25

75

–50 150

0

50

100

gm =

(V

C

PIN)

(FB PIN)

∆I

∆V

TYPICAL PERFORMANCE CHARACTERISTICS

Supply Current vs Input Voltage*

160

140

120

100

80

60

DRIVER CURRENT (mA)

40

20

0

AVERAGE LT1070 POWER SUPPLY CURRENT IS

*

FOUND BY MULTIPLYING DRIVER CURRENT BY DUTY CYCLE, THEN ADDING QUIESCENT CURRENT

= –55°C

T

J

TJ ≥ 25°C

1

23 5

SWITCH CURRENT (A)

4

1070/71 G10

16

TJ = 25°C

15 14 13 12 11 10

9

INPUT CURRENT (mA)

8 7 6

UNDER VERY LOW OUTPUT CURRENT CONDITIONS, DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH 10% OR LESS

0

90% DUTY CYCLE

50% DUTY CYCLE

10% DUTY CYCLE

0% DUTY CYCLE

10

20

INPUT VOLTAGE (V)

I

SWITCH

30*40

≤ 10mA

50

1070/71 G11

LT1070/LT1071

Supply Current vs Supply Voltage (Shutdown Mode)Driver Current* vs Switch Current

160

TJ = 25°C

140

120

100

80

60

SUPPLY CURRENT (µA)

40

20

0

10 20 40

60

0

= 50mV

V

C

VC = 0V

30

SUPPLY VOLTAGE (V)

50

1070/71 G12

60

Normal/Flyback Mode Threshold on Feedback Pin

500 490 480 470

FEEDBACK PIN VOLTAGE

460 450 440 430 420

FEEDBACK PIN VOLTAGE (mV)

410 400

–50

–25 25

Shutdown Thresholds

400

350

300

250

200

150

PIN VOLTAGE (mV)

C

V

100

VC VOLTAGE IS REDUCED UNTIL

50

REGULATOR CURRENT DROPS BELOW 300µA

0

–75

(AT THRESHOLD)

FEEDBACK PIN CURRENT

(AT THRESHOLD)

0

CURRENT

(OUT OF V

–25 25 75–50 1500 50 100

50

PIN)

VOLTAGE

75

TEMPERATURE (°C)

C

TEMPERATURE (°C)

100

125

1070/71 G13

125

1070/71 G16

150

–24 –22 –20 –18

–16

–14 –12 –10 –8 –6

–4

–400

–350

–300

–250

–200

–150

–100

–50

0

Shutdown Mode Supply Current

200 180

FEEDBACK PIN CURRENT (µA)

160 140 120 100

80 60

SUPPLY CURRENT (µA)

40 20

0

Idle Supply Current vs Temperature

11

VC = 0.6V

10

V

C

PIN CURRENT (µA)

9 8 7 6 5 4

IDLE SUPPLY CURRENT (mA)

3 2 1

–75

TJ = 150°C

–55°C ≤ TJ ≤ 125°C

20

30

10 90

VC PIN VOLTAGE (mV)

–25

–50 150

0

TEMPERATURE (°C)

40

V

SUPPLY

V

SUPPLY

60

70

80

100

1070/71 G14

125

1070/71 G14

50

= 60V

= 3V

75

25

50

Error Amplifier Transconductance

Feedback Pin Clamp Voltage

10701fe

5

LT1070/LT1071

UW

TYPICAL PERFORMANCE CHARACTERISTICS

Switch “Off” Characteristics

1000

900 800 700 600 500

V

=

SUPPLY

400 300

SWITCH CURRENT (µA)

200 100

0

3V 15V 40V 55V

20

0

30

10 90

40

50

SWITCH VOLTAGE (V)

60

70

80

100

1070/71 G19

VC Pin Characteristics

300

TJ = 25°C

200

100

0

–100

PIN CURRENT (µA)

C

–200

V

–300

–400

(CURRENT OUT OF V

0.5

0

VFB = 1.5V (CURRENT INTO

PIN)

V

C

V

= 0.8V

FB

1.0

VC PIN VOLTAGE (V)

1.5

C

PIN)

2.0

1070/71 G20

W

BLOCK DIAGRAM

V

IN

2.3V REG

FLYBACK

2.5

ERROR

AMP

Transconductance of Error Amplifier

7000

6000

5000

4000

3000

2000

1000

TRANSCONDUCTANCE (µmho)

0

–1000

1k 100k 1M 10M

10k

16V

θ

g

m

FREQUENCY (Hz)

SWITCH OUT

1070/71 G21

–30

0

30

60

90

120

150

180

210

PHASE (°)

40kHz

OSC

MODE

SELECT

FB

1.24V

REF

–

ERROR

AMP

+

SHUTDOWN CIRCUIT

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OPERATION

The LT1070/LT1071 is a current mode switcher. This means that switch duty cycle is directly controlled by switch current rather than by output voltage. Referring to 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

LOGIC DRIVER

ANTISAT

COMP

V

C

5A, 75V SWITCH

+

0.15V

GAIN ≈ 6

CURRENT

AMP

–

0.02Ω (0.04Ω LT1071)

1070/71 BD

voltage is obtained by using the output of a voltage sensing error amplifier to set current trip level. This technique has several advantages. First, it has immediate response to input voltage variations, unlike ordinary switchers which have notoriously poor line transient response. Second, it reduces the 90° phase shift at

10701fe

6

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OPERATION

LT1070/LT1071

midfrequencies in the energy storage inductor. This greatly simplifies closed-loop frequency compensation under widely varying input voltage or output load conditions. Finally, it allows simple pulse-by-pulse current limiting to provide maximum switch protection under output overload or short-circuit conditions. A low dropout internal regulator provides a 2.3V supply for all internal circuitry of the LT1070/LT1071. This low dropout 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 saturation in the power switch and adjusts driver current instantaneously to limit switch saturation. This minimizes driver dissipation and provides very rapid turn-off of the switch.

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

transformer coupled flyback topology regulator. By regulating the amplitude of the flyback pulse, the output voltage can be regulated with no direct connection between input and output. The output is fully floating up to the breakdown voltage of the transformer windings. Multiple floating outputs are easily obtained with additional windings. A special delay network inside the LT1070/ 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 (VC) has four different functions. It is used for frequency compensation, current limit adjustment, soft starting and total regulator shutdown. 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 (gm) 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 VC pin is pulled to ground through a diode, placing the LT1070/LT1071 in an idle mode. Pulling the VC pin below 0.15V causes total regulator shutdown, with only 50µA supply current for shutdown circuitry biasing. See AN19 for full application details.

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TYPICAL APPLICATIONS

Driving High Voltage FET (for Off-Line

Applications, See AN25)

D1

10V

TO

20V

+

V

IN

V

SW

LT1070/LT1071

GND

1070/71 TA03

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

Driving High Voltage NPN

C1

D2

D

G

Q1

S

V

IN

V

LT1070/LT1071

GND

R2**

R1*

D1

SW

SETS I

*

SETS I

**

B(ON) B(OFF)

1070/71 TA16

Q1

10701fe

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LT1070/LT1071

TYPICAL APPLICATIONS

OPTIONAL INPUT

FILTER

L3

V

–20V

V

IN

2.2µF

+

C5*

100µF

***REQUIRED IF INPUT LEADS ≥2"

PULSE ENGINEERING 92112

D3

+

C3

U

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

Negative Buck Converter

+

D2

1N914

C2 1µF

L1** 100µH

C2 1000µF

2N3906

OPTIONAL

OUTPUT

+

Q1

4µH

FILTER

R1

4.64k

OPTIONAL

OUTPUT

FILTER

L2

C4 1000µF

LOAD

L2

4µH

1070/71 TA12

C5 200µF

R4 10Ω

100mA MINIMUM

1070/71 TA14

+

100µF

IN

GND

C3

LT1070

V

IN

V

SW

+

GND

LT1070

FB

V

C

C1

R3

Positive Buck Converter

V

IN

V

SW

FB

V

C

R3 470Ω

C1 1µF

r

D1

L1** 200µH

R2

1.24k

***REQUIRED IF INPUT LEADS ≥ 2"

PULSE ENGINEERING 92113

R1

3.74k

R2

1.24k

+

–5.2V

4.5A

C4 200µF

5V

4.5A

8

–V

Negative Current Boosted Buck Converter

C1

R1 =

MINIMUM LOAD = 10mA

V

– 0.6V

OUT

1mA

–V 5V 10A

OUT

10701fe

R1

+

R5

V

IN

V

LT1070

V

SW

FB

C

R3

C2

+

GND

IN

T1

C3

1:N

•

D1

2N3906

•

Q1

R2

1.24k

1070/71 TA13

R4

12k

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TYPICAL APPLICATIONS

V

IN

28V

LT1070/LT1071

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

Positive Current Boosted Buck Converter

470Ω 2W

V

IN

V

SW

D2

C3

0.47µF

R6 470Ω

C6

0.002µF

•

1:N

Negative to Positive Buck/Boost Converter

C4*

100µF

L3

OPTIONAL

INPUT

FILTER

V

IN

–12V

***REQUIRED IF INPUT LEADS ≥ 2"

PULSE ENGINEERING 92113

–

2

3

+

200pF

N ≈ 0.25

R5

5k

R4

1.24k

D1

V

OUT

R1

+

5k

C2 5000µF

1070/71 TA19

5V 10A

LT1070

GND V

C

+

C5* 100µF

*REQUIRED IF INPUT LEADS ≥ 2"

FB

R3 680Ω

C1

0.33µF

R2

1kR71.24k

6

V

IN

7

+

V

–

LM308

V

COMP

4

8

Positive to Negative Buck/Boost Converter

†

V

IN

LT1070

R5

470Ω

1W

V

SW

R1

10.7k

FB

V

C

R3

R2

5k

1.24k

C1

0.1µF

L1** 200µH

V

IN

10V TO 30V

C5* 100µF

D2

1N914

+

C3 2µF

REQUIRED IF INPUT LEADS ≥ 2"

*

PULSE ENGINEERING 92113

**

L2

D1

1000µF

R2

1.24k

1070/71 TA05

OPTIONAL

OUTPUT

FILTER

+

C2

L1**

150µH

V

IN

V

SW

+

LT1070

GND

FB

V

C

R3

2.2k C1

0.22µF

C3

V

OUT

12V 2A

R1

11.3k

Q1

D3

1N4001

C4

5µF

†

+

GND

†

TO AVOID START-UP PROBLEMS FOR INPUT VOLTAGES BELOW 10V, CONNECT ANODE OF D3 TO V

IN

C1 MAY BE REDUCED FOR LOWER OUTPUT CURRENTS. C1 ≈ (500µF)(I OUTPUTS, REDUCE R3 TO

1.5k, INCREASE C2 TO 0.3µF

R4

AND REDUCE R6 TO 100Ω.

47Ω

+

†

C1

1000µF

D1

AND REMOVE R5.

) FOR 5V

OUT

R6 470Ω

V

OUT

–12V

1070/71 TA09

2A

10701fe

9

LT1070/LT1071

1070/71 TA04

LT1070/LT1071

V

C

GND

D1

V

X

R1

500Ω

R2

= 2V

TYPICAL APPLICATIONS

U

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

Voltage Boosted Boost Converter

V

IN

LT1070

L1

200µH

V

GND

V

C

R3 10k

SW

+

V

IN

15V

GND

+

C4*

470µF

V

IN

–15V

*REQUIRED IF INPUT LEADS ≥ 2"

R4

680Ω

1W

SW

FB

C2

0.047µF

C3

0.68µF

D2

R2

1.24k

R1

98k

+

1 L1 N = 5

D1

C1 200µF

1070/71 TA10

Negative Boost Regulator

D2

V

IN

LT1070

V

C

FB

R3

3.3k C2

0.22µF

R1 27k

R2

1.24k

+

C3 10µF

D1

TOTAL INDUCTANCE = 4mH INTERLEAVE PRIMARY AND SECONDARY FOR LOW LEAKAGE INDUCTANCE

V

OUT

100V 300mA

R

V

OUT

–28V 1A

O

(MINIMUM LOAD)

1070/71 TA15

C1 1000µF

V

16V TO 24V

–V

IN

Current Boosted Boost Converter

R4

V

IN

V

LT1070

SW

FB

V

C

R3

C2

+

IN

GND

C3

D1

I

D2

N

R1 27k

R2

1.24k

Negative Input/Negative Output Flyback Converter

•

R6

T1

1:N

•

2N3906

R3 1k

Q1

*R1 =

R4

1.24k

1070/71 TA17

+

C3

V

IN

V

LT1070/LT1071

GND V

C

R5

SW

FB

C2

+

R2 5k

R1*

+

V

C1

1070/71 TA11

 – 1.6V

OUT

200µA

V 28V 4A

C1

–V

OUT

External Current Limit

V

IN

V

SW

LT1070/LT1071

External Current Limit

+

V

IN

Q1

R1 1k

C1 1000pF

R

S

GND

FB

V

C

R2

C2

NOTE THAT THE LT1070/LT1071 GND PIN IS NO LONGER COMMON

–

TO V

IN

1070/71 TA06

10701fe

10

U

TYPICAL APPLICATIONS

V

IN

20V TO 30V

V

IN

+

C4* 100µF

*REQUIRED IF INPUT LEADS ≥ 2"

GND

LT1070

V

SW

FB

C

R3

1.5k C2

0.15µF

C3

R4

0.47µF

D2

LT1070/LT1071

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

Flyback Converter

CLAMP TURN-ON

OUT

I

)(LL)

PRI

+ V

SPIKE

PRIMARY FLYBACK VOLTAGE =

LT1070/LT1071 SWITCH VOLTAGE AREA “a” = AREA “b” TO MAINTAIN ZERO DC VOLTS ACROSS PRIMARY

F

SECONDARY VOLTAGE

(N)(VIN)

AREA “c” = AREA “d” TO MAINTAIN ZERO DC VOLTS ACROSS SECONDARY

PRIMARY CURRENT

I

N

PRI

SECONDARY CURRENT

LT1070 SWITCH CURRENT

SNUBBER DIODE CURRENT

V

SNUB

L2

10µH

V

0V

V

OUT

5V

0V

6A

C1 2000µF

C4 200µF

OPTIONAL

FILTER

D1

1N

•

+

a

IN

b

V

c

d

∆I

•

N = 1/3

R1

3.74k

R2

1.24k

0

I

PRI

(I

PRI

t =

V

SNUB

1070/71 TA08

+ V

V

OUT

F

N

PACKAGE DESCRIPTION

K Package

4-Lead TO-3 Metal Can

(Reference LTC DWG # 05-08-1311)

0.320 – 0.350 (8.13 – 8.89)

0.420 – 0.480

(10.67 – 12.19)

0.760 – 0.775

(19.30 – 19.69)

0.038 – 0.043 (0.965 – 1.09)

1.177 – 1.197

(29.90 – 30.40)

72°

18°

0.470 TP P.C.D.

0.060 – 0.135

(1.524 – 3.429)

0.655 – 0.675

(16.64 – 19.05)

0.151 – 0.161 (3.84 – 4.09)

DIA 2 PLC

0.167 – 0.177 (4.24 – 4.49)

0.490 – 0.510

(12.45 – 12.95)

R

U

K4(TO-3) 1098

0.390 – 0.415

(9.906 – 10.541)

0.460 – 0.500

(11.684 – 12.700)

0.067

BSC

(1.70)

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

0.147 – 0.155

(3.734 – 3.937)

0.230 – 0.270

(5.842 – 6.858)

0.330 – 0.370

(8.382 – 9.398)

0.260 – 0.320 (6.60 – 8.13)

0.028 – 0.038

(0.711 – 0.965)

DIA

0.570 – 0.620

(14.478 – 15.748)

SEATING PLANE

0.152 – 0.202

(3.861 – 5.131)

0.165 – 0.180

(4.191 – 4.572)

0.700 – 0.728

(17.78 – 18.491)

0.135 – 0.165

(3.429 – 4.191)

0.620

(15.75)

TYP

* MEASURED AT THE SEATING PLANE

0.045 – 0.055

(1.143 – 1.397)

0.095 – 0.115

(2.413 – 2.921)

0.155 – 0.195* (3.937 – 4.953)

0.013 – 0.023

(0.330 – 0.584)

T5 (TO-220) 0399

OBSOLETE PACKAGE

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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

10701fe

11

LT1070/LT1071

U

TYPICAL APPLICATIONS

V

IN

+

V 5V

*REQUIRED IF INPUT LEADS ≥ 2"

C5*

IN

100µF

LT1070/LT1071

GND

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

Totally Isolated Converter

OPTIONAL

OUTPUT FILTER

D1

1:N

R4

1.5k

V

SW

FB

V

C

C2

0.01µF

C3

0.47µF

N = 0.875 = 7:8 FOR V

OUT

500Ω

5k

•

= 15V

R2

+

t

OFFtON

C1 500µF

C4 500µF

≈16V

V

OUT

N

•

V

IN

0V

15V

COM

–15V

L1

10µF

+

C5 200µF

+

L2

10µF

(N)(V

C6 200µF

SWITCH VOLTAGE

V

F

(DIODE FORWARD VOLTAGE)

SECONDARY VOLTAGE

)

IN

1070/71 TA07

Forward Converter

D2

L1

70µH

V

OUT

5V

+

C1 2000µF

6A

R1

3.74k

R2

1.24k

1070/71 TA18

V

20V TO 30V

D1

T1

IMN

C2

R4

V

IN

V

SW

IN

LT1070

GND V

FB

C

Q1

R3

C3

D3

R6

330Ω

C4

••

•

D4

R5 1Ω

RELATED PARTS

PART NUMBER DESCRIPTION COMMENTS

LT1074/LT1076 High Voltage Switching Regulators 40V Input (60V for HV Versions), 100kHz, 5A and 2A LT1170/LT1171/ 100kHz High Efficiency Switching Regulators 40V Input (65V for HV Versions), 5A/2.5A/1.25A Internal Switch

LT1172 LT1370/LT1371 500kHz High Efficiency Switching Regulators 35V, 6A/3A Internal Switch LT1374/LT1376 100kHz High Efficiency Switching Regulators 25V Input, 4.5A/1.5A Internal Switch LT1765 1.25MHz, 3A, Step-Down Regulator 25V Input, TSSOP-16E, SO8 Package

10701fe

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

 LINEAR TECHNOLOGY CORPORATION 1989

12

Linear T echnolog y Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507

●

www.linear.com

ANALOG DEVICES LT1071CTPBF Datasheet

Specifications and Main Features

Frequently Asked Questions

User Manual