ANALOG DEVICES LT1170HVCTPBF Datasheet

LT1170/LT1171/LT1172

POWER (W) **

100

100kHz, 5A, 2.5A and 1.25A

High Efficiency Switching Regulators

FeaTures DescripTion

n

Wide Input Voltage Range: 3V to 60V

n

Low Quiescent Current: 6mA

n

Internal 5A Switch

(2.5A for LT1171, 1.25A for LT1172)

n

Shutdown Mode Draws Only 50µA Supply Current

n

Very Few External Parts Required

n

Self-Protected Against Overloads

n

Operates in Nearly All Switching Topologies

n

Flyback-Regulated Mode Has Fully Floating Outputs

n

Comes in Standard 5-Pin Packages

n

LT1172 Available in 8-Pin MiniDIP and

Surface Mount Packages

n

Can Be Externally Synchronized

applicaTions

n

Logic Supply 5V at 10A

n

5V Logic to ±15V Op Amp Supply

n

Battery Upconverter

n

Power Inverter (+ to –) or (– to +)

n

Fully Floating Multiple Outputs

USER NOTE:

This data sheet is only intended to provide specifications, graphs, and a general functional
description of the LT1170/LT1171/LT1172. Application circuits are included to show the capability
of the LT1170/LT1171/LT1172. 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 LT1170/LT1171/LT1172 by factoring in
the higher frequency. A CAD design program called SwitcherCAD is also available.

The LT®1170/LT1171/LT1172 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 LT1170/LT1171/LT1172 to be built in a standard
5-pin TO-3 or TO-220 power package as well as the 8-pin
packages (LT1172). This makes them extremely easy to
use and provides “bust proof” operation similar to that
obtained with 3-pin linear regulators.

The LT1170/LT1171/LT1172 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 LT1170/LT1171/LT1172 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 typically for
standby operation.

L, LT, LTC, LTM, Linear Technology, the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.

Typical applicaTion

Boost Converter (5V to 12V)

L1**

5V

µH

50

D1

V

IN

V

+

C3*
100µF

*REQUIRED IF INPUT LEADS ≥ 2"

GND

LT1170

V

C

R3
1k

MBR330

SW

FB

C1
1µF

** COILTRONICS 50-2-52
PULSE ENGINEERING 92114

L2

OUTPUT

10µH

FILTER

C3

100µF

12V

+

C2
1000µF

For more information www.linear.com/LT1170

R1

10.7k
1%

R2

1.24k
1%

1170/1/2 TA01

1A

Maximum Output Power*

LT1170

80

60

BOOST

40

20

0

10

0

FLYBACK

BUCK-BOOST

V

20

INPUT VOLTAGE (V)

BUCK-BOOST

= 30V

V

O

= 5V

O

30

* ROUGH GUIDE ONLY. BUCK MODE

= (5A)(V

P

OUT

SPECIAL TOPOLOGIES DELIVER
MORE POWER.

** DIVIDE VERTICAL POWER SCALE
BY TWO FOR LT1171, BY FOUR
FOR LT1172.

40

50

OUT

)

LT1170/1/2 TA02

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1

LT1170/LT1171/LT1172

1

2

3

4

8

7

6

5

TOP VIEW

GND

V

C

FB

NC*

E2

V

SW

E1

V

IN

J8 PACKAGE

8-LEAD CERDIP

absoluTe MaxiMuM raTings

Supply Voltage

LT1170/LT1171/LT1172HV (Note 2) ....................... 60V

LT1170/LT1171/LT1172 (Note 2) ............................40V

Switch Output Voltage

LT1170/LT1171/LT1172HV .....................................75V

LT1170/LT1171/LT1172 .........................................65V

LT1172S8 ..............................................................60V

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

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

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

pin conFiguraTion

BOTTOM VIEW

V

SW

1

4

V

IN

K PACKAGE

4-LEAD TO-3 METAL CAN

= 150°C, θJC = 2°C/W, θJA = 35°C/W

JMAX

= 100°C, θJC = 2°C/W, θJA = 35°C/W

JMAX

= 150°C, θJC = 4°C/W, θJA = 35°C/W

JMAX

= 100°C, θJC = 4°C/W, θJA = 35°C/W

JMAX

= 150°C, θJC = 8°C/W, θJA = 35°C/W

JMAX

= 100°C, θJC = 8°C/W, θJA = 35°C/W

JMAX

Based on continuous operation.

= 125°C for intermittent fault conditions.

OBSOLETE

T

= 125°C, θJA = 100°C/W

JMAX

* Do not connect Pin 4 of the LT1172 DIP or SO to external

circuitry. This pin may be active in future revisions.

OBSOLETE

LT1170MK: T

LT1170CK: T

LT1171MK: T

LT1171CK: T

LT1172MK: T

LT1172CK: T

T

JMAX

(Note 1)

Operating Junction Temperature Range

LT1170M/LT1171M (OBSOLETE) ....... –55°C to 150°C

LT1172M (OBSOLETE) ....................... –55°C to 125°C

LT1170/LT1171/LT1172HVC,

LT1170/LT1171/LT1172C (Oper.) ............. 0°C to 100°C

LT1170/LT1171/LT1172HVC

LT1170/LT1171/LT1172C (Sh. Ckt.) ........ 0°C to 125°C

LT1170/LT1171/LT1172HVI,

LT1170/LT1171/LT1172I (Oper.) .......... –40°C to 100°C

LT1170/LT1171/LT1172HVI,

LT1170/LT1171/LT1172I (Sh. Ckt.) ...... –40°C to 125°C

V

C

2
3

CASE
IS GND

FB

GND

V

FB

NC*

N8 PACKAGE
8-LEAD PDIP

T

JMAX

* Do not connect Pin 4 of the LT1172 DIP or SO to external

circuitry. This pin may be active in future revisions.

TOP VIEW

1

2

C

3

4

8-LEAD PLASTIC SO

T

= 100°C, θJA = 100°C/W (N)

JMAX

= 100°C, θJA = 120°C/W to 150°C/W

depending on board layout (S)

E2

8

V

7

SW

E1

6

V

5

IN

S8 PACKAGE

FRONT VIEW

5

TAB IS

GND

T

= 100°C, θJA = *°C/W

JMAX

* θ will vary from approximately 25°C/W with 2.8 sq.

in. of 1oz. copper to 45°C/W with 0.20 sq. in. of 1oz.
copper. Somewhat lower values can be obtained with
additional copper layers in multilayer boards.

4
3
2
1

Q PACKAGE

5-LEAD DD

2

V

IN

V

SW

GND
FB
V

C

TOP VIEW

1

NC

2

NC

3

GND

4

V

C

5

FB

6

NC

7

NC

8

NC

SW PACKAGE

16-LEAD PLASTIC SO WIDE

= 100°C, θJA = 150°C/W

T

JMAX

Based on continuous operation.

= 125°C for intermittent fault conditions.

T

JMAX

16

NC

15

NC

14

E2

13

V

SW

12

E1

11

V

IN

10

NC

9

NC

For more information www.linear.com/LT1170

TAB IS

GND

5-LEAD PLASTIC TO-220

LT1170CT/LT1170HVCT: T
LT1171CT/LT1171HVCT: T
LT1172CT/LT1172HVCT: T

Based on continuous operation.

= 125°C for intermittent fault conditions.

T

JMAX

FRONT VIEW

5

4

3

2

1

T PACKAGE

=100°C, θJC = 2°C/W, θJA = 75°C/W

JMAX

=100°C, θJC = 4°C/W, θJA = 75°C/W

JMAX

=100°C, θJC = 8°C/W, θJA = 75°C/W

JMAX

V

IN

V

SW

GND

FB

V

C

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LT1170/LT1171/LT1172

orDer inForMaTion

LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE

LT1172MJ8 (OBSOLETE) LT1172MJ8#TR LT1172 8-Lead CERDIP –55°C to 125°C

LT1172CJ8#PBF (OBSOLETE) LT1172CJ8#TRPBF 8-Lead CERDIP 0°C to 100°C

LT1170MK#PBF (OBSOLETE) LT1170MK#TRPBF 4-Lead TO-3 Metal Can –55°C to 125°C

LT1170CK#PBF (OBSOLETE) LT1170CK#TRPBF 4-Lead TO-3 Metal Can 0°C to 100°C

LT1171MK#PBF (OBSOLETE) LT1171MK#TRPBF 4-Lead TO-3 Metal Can –55°C to 125°C

LT1171CK#PBF (OBSOLETE) LT1171CK#TRPBF 4-Lead TO-3 Metal Can 0°C to 100°C

LT1172MK#PBF (OBSOLETE) LT1172MK#TRPBF 4-Lead TO-3 Metal Can –55°C to 125°C

LT1172CK#PBF (OBSOLETE) LT1172CK#TRPBF 4-Lead TO-3 Metal Can 0°C to 100°C

LT1172CN8#PBF LT1172CN8#TRPBF LT1172 8-Lead PDIP or 8-Lead Plastic SO 0°C to 100°C

LT1172IN8#PBF LT1172IN8#TRPBF LT1172 8-Lead PDIP or 8-Lead Plastic SO –40°C to 100°C

LT1172CS8#PBF LT1172CS8#TRPBF 1172 8-Lead PDIP or 8-Lead Plastic SO 0°C to 100°C

LT1172IS8#PBF LT1172IS8#TRPBF 1172I 8-Lead PDIP or 8-Lead Plastic SO –40°C to 100°C

LT1170CQ#PBF LT1170CQ#TRPBF LT1170 5-Lead DD 0°C to 100°C

LT1170IQ#PBF LT1170IQ#TRPBF LT1170 5-Lead DD –40°C to 100°C

LT1170HVCQ#PBF LT1170HVCQ#TRPBF LT1170HV 5-Lead DD 0°C to 100°C

LT1171CQ#PBF LT1171CQ#TRPBF LT1171 5-Lead DD 0°C to 100°C

LT1171IQ#PBF LT1171IQ#TRPBF LT1171 5-Lead DD –40°C to 100°C

LT1171HVCQ#PBF LT1171HVCQ#TRPBF LT1171HV 5-Lead DD 0°C to 100°C

LT1171HVIQ#PBF LT1171HVIQ#TRPBF LT1171HV 5-Lead DD –40°C to 100°C

LT1172CQ#PBF LT1172CQ#TRPBF LT1172 5-Lead DD 0°C to 100°C

LT1172HVCQ#PBF LT1172HVCQ#TRPBF LT1172HV 5-Lead DD 0°C to 100°C

LT1172HVIQ#PBF LT1172HVIQ#TRPBF LT1172HV 5-Lead DD –40°C to 100°C

LT1172CSW#PBF LT1172CSW#TRPBF LT1172CSW 16-Lead Plastic SO Wide 0°C to 100°C

LT1170CT#PBF LT1170CQ#TRPBF LT1170 5-Lead Plastic TO-220 0°C to 100°C

LT1170IT#PBF LT1170IT#TRPBF LT1170 5-Lead Plastic TO-220 –40°C to 100°C

LT1170HVCT#PBF LT1170HVCT#TRPBF LT1170HV 5-Lead Plastic TO-220 0°C to 100°C

LT1170HVIT#PBF LT1170HVIT#TRPBF LT1170 5-Lead Plastic TO-220 –40°C to 100°C

LT1171CT#PBF LT1171CT#TRPBF LT1171 5-Lead Plastic TO-220 0°C to 100°C

LT1171IT#PBF LT1171IT#TRPBF LT1171 5-Lead Plastic TO-220 –40°C to 100°C

LT1171HVCT#PBF LT1171HVCT#TRPBF LT1171HV 5-Lead Plastic TO-220 0°C to 100°C

LT1171HVIT#PBF LT1171HVIT#TRPBF LT1171HV 5-Lead Plastic TO-220 –40°C to 100°C

LT1172CT#PBF LT1172CT#TRPBF LT1172 5-Lead Plastic TO-220 0°C to 100°C

LT1172HVCT#PBF LT1172HVCT#TRPBF LT1172HV 5-Lead Plastic TO-220 0°C to 100°C

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/

For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/. Some packages are available in 500 unit reels through
designated sales channels with #TRMPBF suffix.

http://www.linear.com/product/LT1170#orderinfo

For more information www.linear.com/LT1170

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3

LT1170/LT1171/LT1172

elecTrical characTerisTics

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

V

FB

BV Output Switch Breakdown Voltage

V

SAT

I

LIM

∆I
∆I

f Switching Frequency

Reference Voltage Measured at Feedback Pin

V

= 0.8V

C

Feedback Input Current VFB = V

REF

Error Amplifier Transconductance ∆IC = ±25µA l3000

Error Amplifier Source or Sink Current

= 1.5V l150

V

C

Error Amplifier Clamp Voltage Hi Clamp, VFB = 1V

Lo Clamp, V

Reference Voltage Line Regulation 3V ≤ V

V

= 0.8V

C

= 1.5V

FB

≤ V

MAX

IN

Error Amplifier Voltage Gain 0.9V ≤ VC ≤ 1.4V 500 800 V/V

Minimum Input Voltage (Note 5)

Supply Current 3V ≤ VIN ≤ V

, VC = 0.6V 6 9 mA

MAX

Control Pin Threshold Duty Cycle = 0

Normal/Flyback Threshold on Feedback Pin 0.4 0.45 0.54 V

Flyback Reference Voltage (Note 5) IFB = 50µA l15.0

Change in Flyback Reference Voltage

Flyback Reference Voltage Line Regulation
(Note 5)

Flyback Amplifier Transconductance (g

) ∆IC = ±10µA 150 300 650 µmho

m

Flyback Amplifier Source and Sink Current V

0.05 ≤ I

I

FB

7V ≤ V

I

FB

3V ≤ V
I

SW

≤ 1mA 4.5 6.8 9 V

FB

= 50µA

≤ V

IN

MAX

= 0.6V Source

C

= 50µA Sink

≤ V

IN

, LT1170/LT1171/LT1172

MAX

= 1.5mA LT1170HV/LT1171HV/LT1172HV

LT1172S8

Output Switch “On” Resistance (Note 3) LT1170

LT1171
LT1172

Control Voltage to Switch Current
T

ransconductance

LT1170
LT1171
LT1172

Switch Current Limit (LT1170) Duty Cycle = 50% TJ ≥ 25°C

Duty Cycle = 50%

TJ < 25°C

Duty Cycle = 80% (Note 4)

(LT1171) Duty Cycle = 50%

Duty Cycle = 50%

T
TJ < 25°C

≥ 25°C

J

Duty Cycle = 80% (Note 4)

(LT1172) Duty Cycle = 50%

Duty Cycle = 50%

T
TJ < 25°C

≥ 25°C

J

Duty Cycle = 80% (Note 4)

Supply Current Increase During Switch

IN

On-Time

SW

, output pin open, unless otherwise noted.

REF

1.224

1.214

l

l

1.244

1.244

1.264

1.274

350 750

1100

4400 6000

2400

7000

200 350

120

1.80

0.25 0.38

l 0.03 %/V

l

0.8

0.6

l

2.6 3.0 V

0.9 1.08

400

2.30

0.52

1.25

16.3 17.6

14.0

18.0

0.01 0.03 %/V

l
l

l
l
l

l
l
l

15
25

65
75
60

32
40

90
90
80

0.15

0.30

0.60

70
70

0.24

0.50

1.00

8
4
2

l
l
l

l
l
l

l
l
l

5
5
4

2.5

2.5

2.0

1.25

1.25

1.00

10
11
10

5.0

5.5

5.0

3.0

3.5

2.5

25 35 mA/A

88 85100 112

l

115

nA
nA

µmho
µmho

µA
µA

µA
µA

A/V
A/V
A/V

kHz

kHz

V
V

V
V

V
V

V
V

V
V
V

Ω
Ω
Ω

A
A
A

A
A
A

A
A
A

4

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For more information www.linear.com/LT1170

LT1170/LT1171/LT1172

(

)

)

)

elecTrical characTerisTics

The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 15V, VC = 0.5V, VFB = V

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

DC

Maximum Switch Duty Cycle

MAX

≤ V

IN

≤ V

MAX

MAX

Shutdown Mode
Supply Current

Shutdown Mode
Threshold Voltage

Flyback Sense Delay Time (Note 5) 1.5 µs

3V ≤ V
V

= 0.05V

C

3V ≤ V

IN

, output pin open, unless otherwise noted.

REF

l

85 92 97 %

100 250 µA

l100 50150 250

300

mV
mV

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.

Note 2: Minimum effective switch “on” time for the LT1170/LT1171/
LT1172 (in current limit only) is ≈ 0.6µs. This limits the maximum safe
input voltage during an output shorted condition. Buck mode and inverting
mode input voltage during an output shorted condition is limited to:

R

I

+ Vf

(

)

V

(max, output shorted) =

IN

buck and inverting mode
R = Inductor DC resistance
I

= 10A for LT1170, 5A for LT1171, and 2.5A for LT1172

L

Vf = Output catch diode forward voltage at I

t = 0.6µs, f = 100kHz switching frequency
Maximum input voltage can be increased by increasing R or Vf.
External current limiting such as that shown in AN19, Figure 39, will

provide protection up to the full supply voltage rating. C1 in Figure 39
should be reduced to 200pF.

15V +

L

f

t

(

(

L

Transformer designs will tolerate much higher input voltages because
leakage inductance limits rate of rise of current in the switch. These
designs must be evaluated individually to assure that current limit is well
controlled up to maximum input voltage.

Boost mode designs are never protected against output shorts because
the external catch diode and inductor connect input to output.

Note 3: Measured with V
2A for LT1171, and 1A for LT1172.

Note 4: For duty cycles (DC) between 50% and 80%, minimum guaranteed
switch current is given by I
(2 – DC) for the LT1171, and I

Note 5: Minimum input voltage for isolated flyback mode is 7V. V
for HV grade in fully isolated mode to avoid switch breakdown.

in hi clamp, VFB = 0.8V. ISW = 4A for LT1170,

C

= 3.33 (2 – DC) for the LT1170, I

LIM

= 0.833 (2 – DC) for the LT1172.

LIM

LIM

MAX

= 1.67

= 55V

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For more information www.linear.com/LT1170

5

LT1170/LT1171/LT1172

16

1.6

REFERENCE VOLTAGE CHANGE (mV)

1.250

FEEDBACK BIAS CURRENT (nA)

800

SUPPLY CURRENT (µA)

160

160

SUPPLY CURRENT (mA)

Typical perForMance characTerisTics

Switch Current Limit vs Duty Cycle* Minimum Input Voltage Switch Saturation Voltage

2.9

12

8

SWITCH CURRENT (A)

4

0

–55°C

125°C

* DIVIDE VERTICAL SCALE BY TWO FOR
LT1171, BY FOUR FOR LT1172.

30

20

DUTY CYCLE (%)

40

0

10

Line Regulation

5

4

3

2

1

0

TJ = –55°C

–1

–2

–3

–4

–5

10

0

20

INPUT VOLTAGE (V)

25°C

50

607080 90 100

TJ = 150°C

TJ = 25°C

30 40

1170/1/2 G01

50

1170/1/2 G04

2.8

2.7

2.6

2.5

MINIMUM INPUT VOLTAGE (V)

2.4

2.3
–75

Reference Voltage vs Temperature

1.248

1.246

1.244

1.242

1.240

1.238

REFERENCE VOLTAGE (V)

1.236

1.234

60

–75 –25

SWITCH CURRENT = I

SWITCH CURRENT = 0A

–50 0

–25

TEMPERATURE (°C)

–50 0

TEMPERATURE (°C)

50 150

25

50 150

25

MAX

100

125

75

1170/1/2 G02

1.4

1.2

1.0

0.8

0.6

0.4

SWITCH SATURATION VOLTAGE (V)

0.2

0

0

* DIVIDE CURRENT BY TWO FOR
LT1171, BY FOUR FOR LT1172.

2

1

SWITCH CURRENT (A)*

Feedback Bias Current
vs Temperature

700

600

500

400

300

200

100

100

125

75

1170/1/2 G05

0

–50 0

–75 –25

100°C

4 5 6 7

3

50 150

75

25

TEMPERATURE (°C)

150°C

–55°C

100

25°C

8

1170/1/2 G03

125

1170/1/2 G06

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

TJ = 25°C

140

120

100

80

60

40

20

0

10 20

0

6

VC = 50mV

VC = 0V

30

SUPPLY VOLTAGE (V)

40

50

1170/1/2 G07

15

TJ = 25°C

140

120

100

80

60

DRIVER CURRENT (mA)

40

20

60

0

* AVERAGE LT1170 POWER SUPPLY CURRENT IS
FOUND BY MULTIPLYING DRIVER CURRENT BY
DUTY CYCLE, THEN ADDING QUIESCENT CURRENT.

0

1 2 3

TJ = –55°C

TJ = ≥ 25°C

SWITCH CURRENT (A)

4

1170/1/2 G08

5

14

NOTE THAT THIS CURRENT DOES NOT

13

INCLUDE DRIVER CURRENT, WHICH IS

12

A FUNCTION OF LOAD CURRENT AND
DUTY CYCLE.

11

10

9

8

7

6

5

10

0

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

20

INPUT VOLTAGE (V)

90% DUTY CYCLE

50% DUTY CYCLE

10% DUTY CYCLE

0% DUTY CYCLE

30 40

50

1170/1/2 G09

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60

For more information www.linear.com/LT1170

LT1170/LT1171/LT1172

TRANSCONDUCTANCE (µmho)

300

11

FEEDBACK VOLTAGE (mV)

500

1000

V
PIN CURRENT (µA)

TIME (µs)

23

Typical perForMance characTerisTics

Shutdown Mode Supply Current Error Amplifier Transconductance VC Pin Characteristics

200

180

160

140

120

100

80

60

SUPPLY CURRENT (µA)

40

20

0

102030

0

VC PIN VOLTAGE (mV)

TJ = 150°C

–55°C ≤ TJ ≤ 125°C

40

607080

50

90 100

1170/1/2 G10

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

0

–75 –25

–50 0

TEMPERATURE (°C)

∆I (V

gm =

∆V (FB PIN)

100

50 150

75

25

PIN)

C

125

1170/1/2 G11

VFB = 1.5V (CURRENT INTO VC PIN)

200

100

0

–100

PIN CURRENT (µA)

C

–200

V

–300

–400

VFB = 0.8V (CURRENT OUT OF VC PIN)

0.5

0 2.0

TJ = 25°C

1.5

1.0

VC PIN VOLTAGE (V)

2.5

1170/1/2 G12

Idle Supply Current vs Temperature

VC = 0.6V

10

9

8

V

7

6

5

4

IDLE SUPPLY CURRENT (mA)

3

2

1

–50 0

–75 –25

= 60V

SUPPLY

V

= 3V

SUPPLY

50 150

75

25

TEMPERATURE (°C)

100

125

1170/1/2 G13

Feedback Pin Clamp Voltage Switch “Off” Characteristics

450

400

350

300

250

200

150

100

50

0

0.1

0.3

0

0.4

0.2
FEEDBACK CURRENT (mA)

Shutdown Thresholds Flyback Blanking Time

400

CURRENT (OUT OF VC PIN)

350

300

250

200

150

PIN VOLTAGE (mV)

C

V

100

50

VC VOLTAGE IS REDUCED UNTIL
REGULATOR CURRENT DROPS
BELOW 300µA

0

–50 0

–75 –25

VOLTAGE

50 150

75

25

TEMPERATURE (°C)

–400

–350

–300

–250

–200

–150

–100

–50

125

1170/1/2 G16

0

100

2.2

2.0

C

1.8

1.6

1.4

1.2

1.0
–50 0

–75

–25

JUNCTION TEMPERATURE (°C)

–55°C

25°C

150°C

0.6

0.5

0.7

50 150

25

75

0.8

0.9 1.0

1170/1/2 G14

100

1170/1/2 G17

125

900

800

700

= 3V

102030

V

SUPPLY

= 15V

SWITCH VOLTAGE (V)

600

V

500

SUPPLY

400

300

SWITCH CURRENT (µA)

200

100

0

0

Isolated Mode Flyback
Reference Voltage

22

21

20

19

18

FLYBACK VOLTAGE (V)

17

16

15

–50 0

–75 –25

TEMPERATURE (°C)

V

SUPPLY

= 40V

40

607080

50

RFB = 500Ω

RFB = 1k

RFB = 10k

50 150

75

25

V

SUPPLY

= 55V

100

90 100

1170/1/2 G15

125

1170/1/2 G18

For more information www.linear.com/LT1170

117012fi

7

LT1170/LT1171/LT1172

TRANSCONDUCTANCE (µmho)

PHASE (DEG)

FEEDBACK PIN VOLTAGE (mV)

Typical perForMance characTerisTics

Transconductance of Error
Amplifier

7000

6000

5000

4000

3000

2000

1000

0

–1000

1k

10k 100k

FREQUENCY (Hz)

block DiagraM

V

IN

θ

g

m

1M 10M

1170/1/2 G19

–30

0

30

60

90

120

150

180

210

Normal/Flyback Mode Threshold on
Feedback Pin

500

490

480

470

460

450

440

430

420

410

400

FEEDBACK PIN VOLTAGE

(AT THRESHOLD)

FEEDBACK PIN CURRENT

–50

–25 25

0

SWITCH

16V

(AT THRESHOLD)

50

TEMPERATURE (°C)

OUT

75

100

125

1170/1/2 G20

–24

–22

FEEDBACK PIN CURRENT (µA)

–20

–18

–16

–14

–12

–10

–8

–6

–4

150

2.3V
REG

100kHz

OSC

MODE

SELECT

FB

–

ERROR

AMP

LOGIC DRIVER

COMP

V

C

FLYBACK

ERROR

AMP

5A, 75V

SWITCH

ANTI-

SAT

+

+

SHUTDOWN
CIRCUIT

1.24V
REF

†

ALWAYS CONNECT E1 TO THE GROUND PIN ON MINIDIP, 8- AND 16-PIN SURFACE MOUNT PACKAGES.
E1 AND E2 INTERNALLY TIED TO GROUND ON TO-3 AND TO-220 PACKAGES.

0.15V

(LT1170 AND LT1171 ONLY)

CURRENT

AMP

≈

GAIN 6

–

E1

0.02Ω
(0.04Ω
(0.16Ω

†

LT1172

LT1171)
LT1172)

0.16Ω

E2

1170/1/2 BD

8

117012fi

For more information www.linear.com/LT1170

operaTion

LT1170/LT1171/LT1172

The LT1170/LT1171/LT1172 are current mode switchers.
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 voltage
is obtained by using the output of a voltage sensing er
ror 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 midfrequencies in the
energy storage inductor
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 conditions. A
low dropout internal regulator provides a 2.3V supply for
all internal circuitry on the LT1170/LT1171/LT1172. This
low dropout design allows input voltage to vary from 3V
to 60V with virtually no change in device performance. A
100kHz oscillator is the basic clock for all internal timing.
It turns “on” the output switch via the logic and driver
circuitry. Special adaptive anti-sat 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 turnoff 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
LT1170/LT1171/LT1172 to disconnect the main error ampli
fier output and connects the output of the flyback amplifier
to the comparator input. The L
then regulate the value of the flyback pulse with respect
to the supply voltage.* This flyback pulse is directly pro
portional 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.

. This greatly simplifies closed

T1170/L

T1171/LT1172 will

-

-

-

A special delay network inside the L
ignores the leakage inductance spike at the leading edge
of the flyback pulse to improve output regulation.

The error signal developed at the
brought out externally. This pin (V
tions. 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 (g
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

pin is pulled to ground through a diode, placing the

the V

C

LT1170/LT1171/LT1172 in an idle mode. Pulling the V
below 0.15V causes total regulator shutdown, with only
50µA supply current for shutdown circuitry biasing. See
Application Note 19 for full application details.

Extra Pins on the MiniDIP and Surface Mount
Packages

The 8- and 16-pin versions of the LT1172 have the emitters
of the power transistor brought out separately from the
ground pin. This eliminates errors due to ground pin voltage
drops and allows the user to reduce switch current limit
2:1 by leaving the second emitter (E2) disconnected. The
first emitter (E1) should always be connected to the ground
pin. Note that switch “on” resistance doubles when E2 is
left open, so efficiency will suffer somewhat when switch
currents exceed 300mA. Also, note that chip dissipation
will actually increase with E2 open during normal load
operation, even though dissipation in current limit mode
will decrease. See “Thermal Considerations” next.

Thermal Considerations When Using the MiniDIP and
SW Packages

The low supply current and high switch efficiency of the
LT1172 allow it to be used without a heat sink in most
applications when the TO-220 or TO-3 package is se
lected. These packages are rated at 50°C/W and 35°C/W
respectively
in ceramic (J) and 130°C/W in plastic (N).

*See note under Block Diagram.

. The miniDIPs, however

T1170/ LT1171/LT1172

comparator input is

) has four different func-

C

) types,

m

C

, are rated at 100°C/W

117012fi

pin

-

For more information www.linear.com/LT1170

9

LT1170/LT1171/LT1172

operaTion

Care should be taken for miniDIP applications to ensure that
the worst case input voltage and load current conditions
do not cause excessive die temperatures. The following
formulas can be used as a rough guide to calculate LT1172
power dissipation. For more details, the reader is referred
to Application Note 19 (AN19), “Efficiency Calculations”
section.

Average supply current (including driver current) is:

≈ 6mA + I

I

IN

= switch current

I

SW

(0.004 + DC/40)

SW

DC = switch duty cycle

Switch power dissipation is given by:

P

R

= (ISW)2 • (RSW)(DC)

SW

= LT1172 switch “on” resistance (1Ω maximum)

SW

Total power dissipation is the sum of supply current times
input voltage plus switch power:

P

= (IIN)(VIN) + P

D(TOT)

SW

In a typical example, using a boost converter to generate
12V at 0.12A from a 5V input, duty cycle is approximately
60%, and switch current is about 0.65A, yielding:

= 6mA + 0.65(0.004 + DC/40) = 18mA

I

IN

P

P

= (0.65)2 • (1Ω)(0.6) = 0.25W

SW

= (5V)(0.018A) + 0.25 = 0.34W

D(TOT)

Temperature rise in a plastic miniDIP would be 130°C/W
times 0.34W, or approximately 44°C. The maximum ambi

­ent temperature would be limited to 100°C (commercial
temperature limit) minus 44°C, or 56°C.

In most applications, full load current is used to calculate
die temperature. However, if overload conditions must
also be accounted for, four approaches are possible. First,
if loss of regulated output is acceptable under overload
conditions, the internal thermal limit of the LT1172 will
protect the die in most applications by shutting off switch
current. Thermal limit is not a tested parameter, however,
and should be considered only for noncritical applications
with temporary overloads. A second approach is to use the

larger TO-220 (T) or TO-3 (K) package which, even without
a heat sink, may limit die temperatures to safe levels under
overload conditions. In critical situations, heat sinking of
these packages is required; especially if overload conditions
must be tolerated for extended periods of time.

The third approach for lower current applications is to
leave the second switch emitter (miniDIP only) open. This
increases switch “on” resistance by 2:1, but reduces switch
current limit by 2:1 also, resulting in a net 2:1 reduction in

2

R switch dissipation under current limit conditions.

I

The fourth approach is to clamp the V

pin to a voltage

C

less than its internal clamp level of 2V. The LT1172 switch
current limit is zero at approximately 1V on the V
and 2A at 2V on the V

pin. Peak switch current can be

C

pin

C

externally clamped between these two levels with a diode.
See AN19 for details.

LT1170/LT1171/LT1172 Synchronizing

The LT1170/LT1171/LT1172 can be externally synchro

­nized in the frequency range of 120kHz to 160kHz. This
is accomplished as shown in the accompanying figures.
Synchronizing occurs when the V

pin is pulled to ground

C

with an external transistor. To avoid disturbing the DC
characteristics of the internal error amplifier, the width of
the synchronizing pulse should be under 0.3µs. C2 sets
the pulse width at ≅ 0.2µs. The effect of a synchronizing
pulse on the LT1170/LT1171/LT1172 amplifier offset can
be calculated from:

⎛
⎜

⎝

IC+

V
R3

⎞

C

⎟
⎠

ΔVOS=

KT

= 26mV at 25°C

⎛

⎞

KT

t

f

(

(

)

)

S

⎜

⎟

q

⎝

⎠

S

I

C

q

tC = pulse width

= pulse frequency

f

S

= VC source current (≈200µA)

I

C

= operating VC voltage (1V to 2V)

V

C

R3 = resistor used to set mid-frequency “zero” in
frequency compensation network.

10

117012fi

For more information www.linear.com/LT1170

operaTion

LT1170/LT1171/LT1172

With tS = 0.2µs, fS = 150kHz, VC = 1.5V, and R3 = 2k, offset
voltage shift is ≈ 3.8mV. This is not particularly bother­some, but note that high offsets could result if R3 were
reduced to a much lower value. Also, the synchronizing

Synchronizing with Bipolar Transistor Synchronizing with MOS Transistor

V

IN

LT1170

GND

V

C

C2

R1

39pF

R2

2.2k

3k

FROM 5V

LOGIC

1170/1/2 OP01

R3

2N2369

C1

transistor must sink higher

currents with low values of
R3, so larger drives may have to be used. The transistor
must be capable of pulling the V

pin to within 200mV of

C

ground to ensure synchronizing.

V

IN

LT1170

GND

V

C

R3

VN2222*

C1

* SILICONIX OR EQUIVALENT

D1

1N4158

R2

2.2k

C2

100pF

D2
1N4158

FROM 5V

LOGIC

1170/1/2 OP02

Typical applicaTions

V

IN

C4*

100µF

20V TO 30V

+

V

IN

V

SW

LT1170

FB

GND

*REQUIRED IF INPUT LEADS ≥ 2"

V

C

R3

1.5k
C2

0.15µF

D3
25V
1W

D2
MUR110

N* = 1/3

1

Flyback Converter

b

V

OUT

d

I

I

PRI

(I

)(LL)

PRI

V

SNUB

CLAMP TURN-ON

SPIKE

+ V

f

N • V

IN

PRI

I

/N

PRI

V

PRIMARY FLYBACK VOLTAGE =

LT1170 SWITCH VOLTAGE
AREA “a” = AREA “b” TO MAINTAIN
ZERO DC VOLTS ACROSS PRIMARY

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

PRIMARY CURRENT

SECONDARY CURRENT

LT1170 SWITCH CURRENT

SNUBBER DIODE CURRENT

OUT

1170/1/2 TA03

N

117012fi

+ Vf

OPTIONAL

L2

FILTER

5µH

C4

100µF

D1

N*

+

C1
2000µF

V
5V
6A

R1

3.74k

R2

1.24k

OUT

V

SNUB

V

a

IN

0V

0V

c

∆I

0

0

0

I

PRI

0

t =

For more information www.linear.com/LT1170

11

LT1170/LT1171/LT1172

Typical applicaTions

E2

E1

GND

OPTIONAL

SHUTDOWN

D2, D3 = ER82.004 600mA SCHOTTKY. OTHER FAST SWITCHING TYPES MAY BE USED.

*

V

AND BATTERY MAY BE TIED TOGETHER. MAXIMUM VALUE FOR V

IN

BATTERY VOLTAGES, HIGHEST EFFICIENCY IS OBTAINED BY RUNNING THE LT1172 V
WILL AUTOMATICALLY TURN OFF THE LT1172. EFFICIENCY IS ABOUT 80% AT I

R1, R2, R3 ARE MADE LARGE TO MINIMIZE BATTERY DRAIN IN SHUTDOWN, WHICH IS APPROXIMATELY V

**

FOR HIGH EFFICIENCY, L1 SHOULD BE MADE ON A FERRITE OR MOLYPERMALLOY CORE. PEAK INDUCTOR CURRENTS ARE ABOUT
600mA AT P

***

OUTPUT RIPPLE IS ABOUT 200mV
A 10Ω, 1µF TANTALUM OUTPUT FILTER.

VN2222

= 0.7Ω. INDUCTOR SERIES RESISTANCE SHOULD BE LESS THAN 0.4Ω FOR HIGH EFFICIENCY.

OUT

(Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)

LCD Contrast Supply

5V*

V

IN

LT1172

TO 400mV

P-P

V

SW

FB

V

C

C4

0.047µF

WITH C2 = 2µF TANTALUM. IF LOWER RIPPLE IS DESIRED, INCREASE C2, OR ADD

P-P

R3
15k

L1**
50µH

R2

100k

*

V

BAT

3V TO 20V

+

D1

R1

200k

IS EQUAL TO THE |NEGATIVE OUTPUT| + 1V. WITH HIGHER

BAT

1N914

C3

0.0047µF

PIN FROM 5V. SHUTTING OFF THE 5V SUPPLY

IN

= 25mA.

OUT

C1
1µF
TANTALUM

D2

D3

/(R1 + R2 + R3).

BAT

V

OUT

–10V TO –26V

C2***
2µF

+

TANTALUM

1170/1/2 TA04

Driving High Voltage FET

(for Off-Line Applications, See AN25)

V

IN

V

SW

20V

+

LT1170

GND

10V TO

G

D1

1170/1/2 TA05

External Current Limit

V

R2

R1

500Ω

X

LT1170

≈ 2V

GND

D1

V

C

1170/1/2 TA06

D
Q1

12

117012fi

For more information www.linear.com/LT1170

LT1170/LT1171/LT1172

Typical applicaTions

Negative-to-Positive Buck-Boost Converter

L1**
50µH

V

IN

+

C4*

100µF

OPTIONAL

INPUT FILTER

L3

V

IN

–20V

REQUIRED IF INPUT LEADS ≥ 2"

*

PULSE ENGINEERING 92114, COILTRONICS 50-2-52

**

†

THIS CIRCUIT IS OFTEN USED TO CONVERT –48V TO 5V. TO GUARANTEE
FULL SHORT-CIRCUIT PROTECTION, THE CURRENT LIMIT CIRCUIT SHOWN
IN AN19, FIGURE 39, SHOULD BE ADDED WITH C1 REDUCED TO 200pF.

GND

LT1170

V

C

R3

2.2k

(Note that maximum output currents are divided by 2 for LT1171, by 4 for LT1172.)

V

SW

FB

C1

0.22µF

†

D1

R2

1.24k

L2

OPTIONAL

OUTPUT

FILTER

+

C2
1000µF

Q1

C3

R1

11.3k

1170/1/2 TA07

V
12V
2A

OUT

External Current Limit

+

V

IN

–

R1

Q1

NOTE THAT THE LT1170
GND PIN IS NO LONGER
COMMON TO V

1k

C1
1000pF

–

.

IN

R

S

GND

V

IN

LT1170

V

SW

FB

V

C

R2

C2

1170/1/2 TA08

REQUIRED IF INPUT LEADS ≥ 2"

*

PULSE ENGINEERING 92114

**

COILTRONICS 50-2-52

OPTIONAL

INPUT FILTER

L3

V

IN

–20V

C3*

100µF

Negative Buck Converter

+

D1

V

IN

V

SW

L1**

50µH

+

LT1170

FB

GND

V

C

C1

R3

R2

1.24k

C2
1000µF

2N3906

R4

12k

OPTIONAL

OUTPUT

FILTER

LOAD

–5.2V

4.5A

+

1170/1/2 TA09

C4
200µF

R1

4.64k

Q1

For more information www.linear.com/LT1170

117012fi

13

LT1170/LT1171/LT1172

†

†

Typical applicaTions

Positive-to-Negative Buck-Boost Converter

D3

1N4001

1µF

V

IN

+

C4

LT1170

GND

†

R5

470Ω, 1W

V

SW

FB

V

C

R3
5k

C2

0.1µF

High Efficiency Constant Current Charger

+

R1

10.7k

R2

1.24k

L1**

50µH

1N914

+ +

C5
100µF*

D2

C3
2µF

V

IN

10V TO
30V

47Ω

D1

REQUIRED IF INPUT LEADS ≥ 2"

*

PULSE ENGINEERING 92114, COILTRONICS 50-2-52

**

†

TO AVOID STARTUP PROBLEMS FOR INPUT VOLTAGES
BELOW 10V, CONNECT ANODE OF D3 TO V
REMOVE R5. C1 MAY BE REDUCED FOR LOWER OUTPUT
CURRENTS. C1 ≈ (500µF)(I

R4

FOR 5V OUTPUTS, REDUCE R3 TO 1.5k, INCREASE C2 TO

0.3µF, AND REDUCE R6 TO 100Ω.

†

C1

1000µF

R6
470Ω

V

OUT

–12V
2A

OUT

).

, AND

IN

1170/1/2 TA10

INPUT VOLTAGE

+ 2V < 35V

> V

BAT

+ +

C1

200

µF

35V

D1

1N5819

C2

µF

2.2
35V

TANTALUM

RUN = 0V

SHUTDOWN = 5V

R6

78k

R3

+

V

LT1006

–

V

25k

–

+

R5

0.05Ω

R4
1k

100

V

SW

LT1171

V

IN

GND

2N3904

R8

R7

1k

22k

FB

V

C

+

C3

0.47

D2
MBR340

R2
1k

C4

0.01

µF

µF

1.244V • R4

I =

CHRG

* L2 REDUCES RIPPLE CURRENT INTO
THE BATTERY BY ABOUT 20:1.
IT MAY BE OMITTED IF DESIRED.

L1

µH, 1A

R3 • R5

+

10

µH, 1A

C4
200µF
25V

L2*

= 1A AS SHOWN

1A

+

BATTERY
2V TO 25V

1170/1/2 TA11

Backlight CCFL Supply (see AN45 for details)

INPUT VOLTAGE

4.5V TO 20V

E2

+

10µF

TANT

E1

GND

1k

V

IN

LT1172

2µF

+

1N5818

V

V

C

SW

L1**

300µH

FB

C6

1µF

Q1,Q2 = BCP56 OR MPS650/561

*

COILTRONICS CTX300-4

**

SUMIDA 6345-020 OR COILTRONICS 110092-1

***

†

A MODIFICATION WILL ALLOW OPERATION DOWN TO 4.5V. CONSULT FACTORY.

A

Q1*

0.02µF

Q2*

B

L2***

1N914

33pF

3kV

D1

R3

10k

LAMP

D2
1N914

R1

560Ω

50k

INTENSITY

ADJUST

1170/1/2 TA12

117012fi

14

For more information www.linear.com/LT1170

Typical applicaTions

V

IN

2.2µF

+

C5*
100µF

D3

+

C3

GND

Positive Buck Converter

V

IN

V

SW

LT1170

FB

V

C

R3
470Ω

C1
1µF

r

D1

Negative Boost Regulator

LT1170/LT1171/LT1172

REQUIRED IF INPUT LEADS ≥ 2"

*

PULSE ENGINEERING 92114

**

COILTRONICS 50-2-52

R1

3.74k

R2

1.24k

D2

1N914

+

C2
1µF

L1**
50µH

1000µF

OPTIONAL

OUTPUT

FILTER

+

C4

L2

4µH

C5
200µF

R4
10Ω

5V, 4.5A

100mA
MINIMUM

1170/1/2 TA13

D2

V

SW

GND

IN

LT1170

R1
27k

+ +

C3
10µF

FB

V

C

R3

3.3k
C2

0.22µF

R2

1.24k

D1

C1
1000µF

V

OUT

–28V, 1A

R

O

(MINIMUM
LOAD)

1170/1/2 TA14

470µF

V

–15V

V

+

C4*

L1

IN

50µH

REQUIRED IF INPUT LEADS ≥ 2"

*

Driving High Voltage NPN

C1

D2

V

IN

LT1170

GND

R2**

V

SW

R1*

D1

SETS IB (ON)

*

SETS I

**

B

Q1

(OFF)

1170/1/2 TA15

For more information www.linear.com/LT1170

117012fi

15

LT1170/LT1171/LT1172

L1

V

Typical applicaTions

Forward Converter

V

20V TO 30V

D1

T1

1

M

R4

V

IN

V

SW

IN

GND

LT1170

FB

V

C

Q1

R3

C3

C2

D3

R6

330Ω

C4

N

D2

D4

R5

Ω

1

25µH

2000

V

OUT

5V, 6A

+

C1

µF

R1

3.74k

R2

1.24k

1170/1/2 TA16

High Efficiency 5V Buck Converter

IN

C5

0.03µF

GND

DIODE

LT1432

V

IN

4.7µF
TANT

GND

D2

1N4148

C3

+

L1

50µH

0.013Ω

+

V

V

LIM

V

OUT

* R2 IS MADE FROM PC BOARD
COPPER TRACES.
** MAXIMUM CURRENT IS DETERMINED
BY THE CHOICE OF LT1070 FAMILY.
SEE APPLICATION SECTION.

V

C6

0.02µF

0.1µF

220pF

SW

LT1170

FB

V

C

R1
680Ω

C4

D1

V

C

V

IN

MODE

+

C1
330µF
35V

MBR330p

MODE LOGIC

<0.3V = NORMAL MODE
>2.5V = SHUTDOWN
OPEN = BURST MODE

R2*

10µH

3A

100µF

16V

+

+

×

C2
390µF
16V

OPTIONAL
OUTPUT
FILTER

V

OUT

5V
3A**

1170/1/2 TA17

16

117012fi

For more information www.linear.com/LT1170

LT1170/LT1171/LT1172

package DescripTion

Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.

J8 Package

8-Lead CERDIP (Narrow .300 Inch, Hermetic)

(Reference LTC DWG # 05-08-1110)

CORNER LEADS OPTION

(4 PLCS)

.023 – .045

(0.584 – 1.143)

HALF LEAD

.045 – .068

(1.143 – 1.650)

FULL LEAD

OPTION

.300 BSC

(7.62 BSC)

.008 – .018

(0.203 – 0.457)

NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE
OR TIN PLATE LEADS

0 – 15

OPTION

.005

(0.127)

MIN

.025

(0.635)

RAD TYP

.045 – .065

(1.143 – 1.651)

.014 – .026

(0.360 – 0.660)

8 7

1 2

.405

(10.287)

MAX

6 5

3

4

.220 – .310

(5.588 – 7.874)

.015 – .060

(0.381 – 1.524)

.100

(2.54)

BSC

.200

(5.080)

MAX

.125

3.175
MIN

J8 0801

.320 – .350

(8.13 – 8.89)

.420 – .480

(10.67 – 12.19)

.760 – .775

(19.30 – 19.69)

.038 – .043

(0.965 – 1.09)

K Package

4-Lead TO-3 Metal Can

(Reference LTC DWG # 05-08-1311)

.060 – .135

(1.524 – 3.429)

(OBSOLETE PACKAGE)

For more information www.linear.com/LT1170

1.177 – 1.197

(29.90 – 30.40)

72°

18°

.470 TP

P.C.D.

.655 – .675

(16.64 – 19.05)

.151 – .161

(3.84 – 4.09)

DIA 2 PLC

.167 – .177

(4.24 – 4.49)

R

.490 – .510

(12.45 – 12.95)

R

K4(TO-3) 0801

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17

LT1170/LT1171/LT1172

N8 REV I 0711

NOTE:

1. DIMENSIONS ARE

*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)

N Package

package DescripTion

Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.

8-Lead PDIP (Narrow .300 Inch)

(Reference LTC DWG # 05-08-1510 Rev I)

.400*

(10.160)

MAX

8 7 6

.255 ±.015*

(6.477 ±0.381)

5

.300 – .325

(7.620 – 8.255)

.008 – .015

(0.203 – 0.381)

+.035

.325

–.015
+0.889

8.255

( )

–0.381

INCHES

MILLIMETERS

.065

(1.651)

TYP

1 2

.045 – .065

(1.143 – 1.651)

.100

(2.54)

BSC

3

4

.130 ±.005

(3.302 ±0.127)

.120

(3.048)

MIN

.018 ±.003

(0.457 ±0.076)

.020

(0.508)

MIN

18

For more information www.linear.com/LT1170

117012fi

LT1170/LT1171/LT1172

(1.270 ±0.305)

2. DRAWING NOT TO SCALE

(1.524)

Q Package

package DescripTion

Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.

5-Lead Plastic DD Pak

(Reference LTC DWG # 05-08-1461 Rev F)

.256

(6.502)

.060

.300

(7.620)

BOTTOM VIEW OF DD PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK

.060

(1.524)

.075

(1.905)

.183

(4.648)

.420

.060

(1.524)

TYP

.330 – .370

(8.382 – 9.398)

.143

3.632

( )

+.012
–.020

+0.305
–0.508

.350

.585

(9.906 – 10.541)

.028 – .038

(0.711 – 0.965)

TYP

.080

.205

.390 – .415

15° TYP

.067

(1.702)

BSC

.420
.276

.165 – .180

(4.191 – 4.572)

.059

(1.499)

TYP

.013 – .023

(0.330 – 0.584)

DETAIL A

DETAIL A

.325

.585

.045 – .055

(1.143 – 1.397)

+.008

.004

–.004

+0.203

0.102

( )

–0.102

.095 – .115

(2.413 – 2.921)

.050 ±.012

0° – 7° TYP0° – 7° TYP

RECOMMENDED SOLDER PAD LAYOUT

NOTE:

1. DIMENSIONS IN INCH/(MILLIMETER)

.067

.320

.090

.042

FOR THICKER SOLDER PASTE APPLICATIONS

.067

RECOMMENDED SOLDER PAD LAYOUT

For more information www.linear.com/LT1170

.090

.042

Q(DD5) 0811 REV F

117012fi

19

LT1170/LT1171/LT1172

(0.101 – 0.254)

.030

4. PIN 1 CAN BE BEVEL EDGE OR A DIMPLE

S8 Package

package DescripTion

Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.

8-Lead Plastic Small Outline (Narrow .150 Inch)

(Reference LTC DWG # 05-08-1610 Rev G)

.189 – .197

(4.801 – 5.004)

8

NOTE 3

7

5

6

.050 BSC

.045 ±.005

.245

MIN

±.005

TYP

RECOMMENDED SOLDER PAD LAYOUT

.010 – .020

(0.254 – 0.508)

.008 – .010

(0.203 – 0.254)

NOTE:

1. DIMENSIONS IN

2. DRAWING NOT TO SCALE

3. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

× 45°

.016 – .050

(0.406 – 1.270)

INCHES

(MILLIMETERS)

.160 ±.005

.228 – .244

(5.791 – 6.197)

.053 – .069

(1.346 – 1.752)

0°– 8° TYP

.014 – .019

(0.355 – 0.483)

TYP

.150 – .157

(3.810 – 3.988)

NOTE 3

1

3

2

4

.004 – .010

.050

(1.270)

BSC

SO8 REV G 0212

20

117012fi

For more information www.linear.com/LT1170

LT1170/LT1171/LT1172

package DescripTion

Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.

SW Package

16-Lead Plastic Small Outline (Wide .300 Inch)

(Reference LTC DWG # 05-08-1620)

.030 .005

TYP

N

.420
MIN

1 2 3 N/2

RECOMMENDED SOLDER PAD LAYOUT

.291 – .299

(7.391 – 7.595)

NOTE 4

.010 – .029

.005

(0.127)

RAD MIN

.009 – .013

(0.229 – 0.330)

NOTE:

1. DIMENSIONS IN

2. DRAWING NOT TO SCALE

3. PIN 1 IDENT, NOTCH ON TOP AND CAVITIES ON THE BOTTOM OF PACKAGES ARE THE MANUFACTURING OPTIONS.
THE PART MAY BE SUPPLIED WITH OR WITHOUT ANY OF THE OPTIONS

4. THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .006" (0.15mm)

(0.254 – 0.737)

NOTE 3

.016 – .050

(0.406 – 1.270)

INCHES

(MILLIMETERS)

.050 BSC

× 45°

.045 .005

.325 .005

0 – 8 TYP

NOTE 3

.093 – .104

(2.362 – 2.642)

(1.270)

16

N

1

.050

BSC

.014 – .019

(0.356 – 0.482)

.398 – .413

(10.109 – 10.490)

15 14

2 3

TYP

NOTE 4

13

4

12

11

5

6

10 9

.394 – .419

(10.007 – 10.643)

N/2

7 8

.037 – .045

(0.940 – 1.143)

.004 – .012

(0.102 – 0.305)

S16 (WIDE) 0502

For more information www.linear.com/LT1170

117012fi

21

LT1170/LT1171/LT1172

package DescripTion

Please refer to http://www.linear.com/product/LT1170#packaging for the most recent package drawings.

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

.390 – .415

(9.906 – 10.541)

.460 – .500

(11.684 – 12.700)

.067

BSC

(1.70)

.147 – .155

(3.734 – 3.937)

.230 – .270

(5.842 – 6.858)

.330 – .370

(8.382 – 9.398)

.028 – .038

(0.711 – 0.965)

DIA

.570 – .620

(14.478 – 15.748)

SEATING PLANE

.260 – .320

(6.60 – 8.13)

.700 – .728

(17.78 – 18.491)

.152 – .202

(3.861 – 5.131)

(3.429 – 4.191)

.165 – .180

(4.191 – 4.572)

.135 – .165

.620

(15.75)

TYP

.045 – .055

(1.143 – 1.397)

.095 – .115

(2.413 – 2.921)

.155 – .195*

(3.937 – 4.953)

.013 – .023

(0.330 – 0.584)

* MEASURED AT THE SEATING PLANE

T5 (TO-220) 0801

22

117012fi

For more information www.linear.com/LT1170

LT1170/LT1171/LT1172

revision hisTory

REV DATE DESCRIPTION PAGE NUMBER

G 3/10 Updated to Reactivate LT1172M from Obsoleted Parts List 2

H 6/16 Removed #PBF from MJ8 part number in first line 3

I 3/17 Corrected Flyback Amplifier Source and Sink Current units to µA from mA

Obsoleted LT1172M and LT1172MJ8

(Revision history begins at Rev G)

4

2, 3

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.

For more information www.linear.com/LT1170

117012fi

23

LT1170/LT1171/LT1172

Typical applicaTion

Positive Current Boosted Buck Converter

V

IN

28V

V

IN

V

LT1170

V

C

C5*

100µF

GND

+

SW

FB

R3
680Ω

C1

0.33

470Ω
2W

D2

R7

1k

C4

0.01

µF

C3

µF

0.47

0.002

V

6

µF

LM308

4

200pF

R6
470Ω

C6

µF

R2

1.24k

IN

7

2

–

3

+

8

R4

1.24k

1: N

N ≈ 0.25

R5
5k

D1

V

OUT

R1

+

5k

5V, 10A

C2
5000µF

* REQUIRED IF INPUT LEADS ≥ 2"

1170/1/2 TA18

relaTeD parTs

PART NUMBER DESCRIPTION COMMENTS

LT1070/LT1071/LT1072 5A/2.5A/1.25A High Efficiency Switching Regulators 40kHz, V

LT1074/LT1076 5.5A/2A Step-Down Switching Regulators 100kHz, Also for Positive-to-Negative Conversion

LT1082 1A, High Voltage, High Efficiency Switching Regulator V

LT1268/LT1268B 7.5A, 150kHz Switching Regulators V

IN

IN

LT1269/LT1271 4A High Efficiency Switching Regulators 100kHz/60kHz, V

LT1270/LT1270A 8A and 10A High Efficiency Switching Regulators 60kHz, V

LT1370 500kHz High Efficiency 6A Switching Regulator High Power Boost, Flyback, SEPIC

LT1371 500kHz High Efficiency 3A Switching Regulator Good for Boost, Flyback, Inverting, SEPIC

LT1372/LT1377 500kHz and 1MHz High Efficiency 1.5A Switching Regulators Directly Regulates ±V

LT1373 250kHz Low Supply Current High Efficiency 1.5A Switching Regulator Low 1mA Quiescent Current

LT1374 4A, 500kHz Step-Down Switching Regulator Synchronizable, V

LT1375/LT1376 1.5A, 500kHz Step-Down Switching Regulators Up to 1.25A Out from an SO-8

LT1425 Isolated Flyback Switching Regulator 6W Output, ±5% Regulation, No Optocoupler Needed

LT1507 500kHz Monolithic Buck Mode Switching Regulator 1.5A Switch, Good for 5V to 3.3V

LT1533 Ultralow Noise 1A Switching Regulator Push-Pull, <100µV

to 60V, VSW to 75V

IN

to 75V, VSW to 100V, Telecom

to 30V, VSW to 60V

to 30V, VSW to 60V

IN

to 30V, VSW to 60V

IN

OUT

to 25V

IN

Output Noise

P-P

24

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone]

For more information www.linear.com/LT1170

●

www.linear.com/LT1170

117012fi

LT 0317 REV I • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 1991