LT1170HVCQ#TR - Linear Technology Corporation

LT1170/LT1171/LT1172

117012fg

TYPICAL APPLICATION

FEATURES DESCRIPTION

100kHz, 5A, 2.5A and 1.25A

High Efficiency Switching Regulators

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, con-

trol 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 exter-

nal 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 and SwitcherCAD are registered

trademarks of Linear Technology Corporation. All other trademarks are the property of their

respective owners.

Boost Converter (5V to 12V)

APPLICATIONS

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

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.

Maximum Output Power*

1170/1/2 TA01

MBR330

1000µF

1µF

10.7k

1.24k

LT1170

GND

VIN

*REQUIRED IF INPUT LEADS r2" ** COILTRONICS 50-2-52

PULSE ENGINEERING 92114

VSW

OUTPUT

FILTER

10µH

L1**

50µH

100µF

12V

C3*

100µF

INPUT VOLTAGE (V)

POWER (W) **

100

040

LT1170/1/2 TA02

10 20 30 50

* ROUGH GUIDE ONLY. BUCK MODE

OUT = (5A)(VOUT)

SPECIAL TOPOLOGIES DELIVER

MORE POWER.

** DIVIDE VERTICAL POWER SCALE

BY TWO FOR LT1171, BY FOUR

FOR LT1172.

BOOST

BUCK-BOOST

VO = 30V

FLYBACK

BUCK-BOOST

VO = 5V

LT1170

LT1170/LT1171/LT1172

117012fg

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

(Note 1)

PIN CONFIGURATION

Operating Junction Temperature Range

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

LT1172M ............................................ –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

TOP VIEW

GND

NC*

VSW

VIN

J8 PACKAGE

8-LEAD CERDIP

TJMAX = 125°C, θJA = 100°C/W

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

circuitry. This pin may be active in future revisions.

VSW VC

CASE

IS GND

VIN

K PACKAGE

4-LEAD TO-3 METAL CAN

BOTTOM VIEW

LT1170MK: TJMAX = 150°C, θJC = 2°C/W, θJA = 35°C/W

LT1170CK: TJMAX = 100°C, θJC = 2°C/W, θJA = 35°C/W

LT1171MK: TJMAX = 150°C, θJC = 4°C/W, θJA = 35°C/W

LT1171CK: TJMAX = 100°C, θJC = 4°C/W, θJA = 35°C/W

LT1172MK: TJMAX = 150°C, θJC = 8°C/W, θJA = 35°C/W

LT1172CK: TJMAX = 100°C, θJC = 8°C/W, θJA = 35°C/W

Based on continuous operation.

TJMAX = 125°C for intermittent fault conditions.

OBSOLETE

N8 PACKAGE

8-LEAD PDIP

TOP VIEW

GND

NC*

VSW

VIN

S8 PACKAGE

8-LEAD PLASTIC SO

TJMAX = 100°C, θJA = 100°C/W (N)

TJMAX = 100°C, θJA = 120°C/W to 150°C/W

depending on board layout (S)

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

circuitry. This pin may be active in future revisions.

Q PACKAGE

5-LEAD DD

VIN

VSW

GND

FRONT VIEW

TJMAX = 100°C, θJA = *°C/W

* 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.

TOP VIEW

SW PACKAGE

16-LEAD PLASTIC SO WIDE

GND

VSW

VIN

TJMAX = 100°C, θJA = 150°C/W

Based on continuous operation.

TJMAX = 125°C for intermittent fault conditions.

T PACKAGE

5-LEAD PLASTIC TO-220

VIN

VSW

GND

FRONT VIEW

LT1170CT/LT1170HVCT: TJMAX =100°C, θJC = 2°C/W, θJA = 75°C/W

LT1171CT/LT1171HVCT: TJMAX =100°C, θJC = 4°C/W, θJA = 75°C/W

LT1172CT/LT1172HVCT: TJMAX =100°C, θJC = 8°C/W, θJA = 75°C/W

Based on continuous operation.

TJMAX = 125°C for intermittent fault conditions.

LT1170/LT1171/LT1172

117012fg

ORDER INFORMATION

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

LT1172MJ8#PBF LT1172MJ8#TRPBF 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 8-Lead PDIP or 8-Lead Plastic SO 0°C to 100°C

LT1172IN8#PBF LT1172IN8#TRPBF 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 5-Lead DD 0°C to 100°C

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Consult LTC Marketing for information on non-standard lead based finish parts.

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/

LT1170/LT1171/LT1172

117012fg

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 = VREF, output pin open, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

VREF Reference Voltage Measured at Feedback Pin

VC = 0.8V l

1.224

1.214

1.244

1.264

1.274

IBFeedback Input Current VFB = VREF

350 750

1100

gmError Amplifier Transconductance ∆IC = ±25µA

3000

2400

4400 6000

7000

µmho

Error Amplifier Source or Sink Current VC = 1.5V

150

120

200 350

400

µA

Error Amplifier Clamp Voltage Hi Clamp, VFB = 1V

Lo Clamp, VFB = 1.5V

1.80

0.25 0.38

2.30

0.52

Reference Voltage Line Regulation 3V ≤ VIN ≤ VMAX

VC = 0.8V

l 0.03 %/V

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

Minimum Input Voltage (Note 5) l2.6 3.0 V

IQSupply Current 3V ≤ VIN ≤ VMAX, VC = 0.6V 6 9 mA

Control Pin Threshold Duty Cycle = 0

0.8

0.6

0.9 1.08

1.25

Normal/Flyback Threshold on Feedback Pin 0.4 0.45 0.54 V

VFB Flyback Reference Voltage (Note 5) IFB = 50µA

15.0

14.0

16.3 17.6

18.0

Change in Flyback Reference Voltage 0.05 ≤ IFB ≤ 1mA 4.5 6.8 9 V

Flyback Reference Voltage Line Regulation

(Note 5)

IFB = 50µA

7V ≤ VIN ≤ VMAX

0.01 0.03 %/V

Flyback Amplifier Transconductance (gm)∆I

C = ±10µA 150 300 650 µmho

Flyback Amplifier Source and Sink Current VC = 0.6V Source

IFB = 50µA Sink

BV Output Switch Breakdown Voltage 3V ≤ VIN ≤ VMAX, LT1170/LT1171/LT1172

ISW = 1.5mA LT1170HV/LT1171HV/LT1172HV

LT1172S8

VSAT Output Switch “On” Resistance (Note 3) LT1170

LT1171

LT1172

0.15

0.30

0.60

0.24

0.50

1.00



Control Voltage to Switch Current

Transconductance

LT1170

LT1171

LT1172

A/V

ILIM 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% TJ ≥ 25°C

Duty Cycle = 50% TJ < 25°C

Duty Cycle = 80% (Note 4)

2.5

2.0

5.0

5.5

5.0

(LT1172) Duty Cycle = 50% TJ ≥ 25°C

Duty Cycle = 50% TJ < 25°C

Duty Cycle = 80% (Note 4)

1.25

1.00

3.0

3.5

2.5

∆IIN

∆ISW

Supply Current Increase During Switch

On-Time

25 35 mA/A

f Switching Frequency

100 112

115

kHz

LT1170/LT1171/LT1172

117012fg

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

DCMAX Maximum Switch Duty Cycle l85 92 97 %

Shutdown Mode

Supply Current

3V ≤ VIN ≤ VMAX

VC = 0.05V

100 250 µA

Shutdown Mode

Threshold Voltage

3V ≤ VIN ≤ VMAX

100

150 250

300

Flyback Sense Delay Time (Note 5) 1.5 µs

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 = VREF, output pin open, unless otherwise noted.

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:

VIN (max, output shorted) =

15V +R

(

)

(

)

+Vf

(

)

(

)

buck and inverting mode

R = Inductor DC resistance

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

Vf = Output catch diode forward voltage at IL

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.

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

2A for LT1171, and 1A for LT1172.

Note 4: For duty cycles (DC) between 50% and 80%, minimum guaranteed

switch current is given by ILIM = 3.33 (2 – DC) for the LT1170, ILIM = 1.67

(2 – DC) for the LT1171, and ILIM = 0.833 (2 – DC) for the LT1172.

Note 5: Minimum input voltage for isolated flyback mode is 7V. VMAX = 55V

for HV grade in fully isolated mode to avoid switch breakdown.

LT1170/LT1171/LT1172

117012fg

TYPICAL PERFORMANCE CHARACTERISTICS

Line Regulation Reference Voltage vs Temperature

Feedback Bias Current

vs Temperature

Supply Current vs Supply Voltage

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

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

DUTY CYCLE (%)

SWITCH CURRENT (A)

040

1170/1/2 G01

20 30 50 60 70 80 90 100

25°C

125°C

–55°C

* DIVIDE VERTICAL SCALE BY TWO FOR

LT1171, BY FOUR FOR LT1172.

TEMPERATURE (°C)

–75

MINIMUM INPUT VOLTAGE (V)

–25 25 50 150

1170/1/2 G02

–50 0 75 100 125

2.9

2.8

2.7

2.6

2.5

2.4

2.3

SWITCH CURRENT = 0A

SWITCH CURRENT = IMAX

SWITCH CURRENT (A)*

SWITCH SATURATION VOLTAGE (V)

1170/1/2 G03

123

1.6

1.4

1.2

1.0

0.8

0.6

0.4

0.2

4567

25°C

150°C

–55°C

100°C

* DIVIDE CURRENT BY TWO FOR

LT1171, BY FOUR FOR LT1172.

INPUT VOLTAGE (V)

REFERENCE VOLTAGE CHANGE (mV)

10 20 30 40

1170/1/2 G04

–1

–2

–3

–4

–5 60

TJ = 150°C

TJ = –55°C TJ = 25°C

TEMPERATURE (°C)

REFERENCE VOLTAGE (V)

1170/1/2 G05

1.250

1.248

1.246

1.244

1.242

1.240

1.238

1.236

1.234

–75 –25 25 50 150

–50 0 75 100 125

TEMPERATURE (°C)

FEEDBACK BIAS CURRENT (nA)

1170/1/2 G06

800

700

600

500

400

300

200

100

–75 –25 25 50 150

–50 0 75 100 125

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

10 20 30 40

160

140

120

100

50 60

1170/1/2 G07

VC = 50mV

VC = 0V

TJ = 25°C

SWITCH CURRENT (A)

DRIVER CURRENT (mA)

123

160

140

120

100

1170/1/2 G08

TJ = –55°C

TJ = ≥ 25°C

* AVERAGE LT1170 POWER SUPPLY CURRENT IS

FOUND BY MULTIPLYING DRIVER CURRENT BY

DUTY CYCLE, THEN ADDING QUIESCENT CURRENT.

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

10 20 30 40

1170/1/2 G09

560

TJ = 25°C

NOTE THAT THIS CURRENT DOES NOT

INCLUDE DRIVER CURRENT, WHICH IS

A FUNCTION OF LOAD CURRENT AND

DUTY CYCLE.

90% DUTY CYCLE

50% DUTY CYCLE

10% DUTY CYCLE

0% DUTY CYCLE

* UNDER VERY LOW OUTPUT CURRENT CONDITIONS,

DUTY CYCLE FOR MOST CIRCUITS WILL APPROACH

10% OR LESS.

LT1170/LT1171/LT1172

117012fg

TYPICAL PERFORMANCE CHARACTERISTICS

Idle Supply Current vs Temperature Feedback Pin Clamp Voltage Switch “Off” Characteristics

Shutdown Thresholds Flyback Blanking Time

Isolated Mode Flyback

Reference Voltage

Shutdown Mode Supply Current Error Amplifier Transconductance VC Pin Characteristics

VC PIN VOLTAGE (mV)

SUPPLY CURRENT (µA)

200

180

160

140

120

100

1170/1/2 G10

10 20 30 50 60 70 80 90 100

TJ = 150°C

–55°C ≤ TJ ≤ 125°C

TEMPERATURE (°C)

TRANSCONDUCTANCE (µmho)

5000

4500

4000

3500

3000

2500

2000

1500

1000

500

1170/1/2 G11

–75 –25 25 50 150

–50 0 75 100 125

gm = $I (VC PIN)

$V (FB PIN)

VC PIN VOLTAGE (V)

300

200

100

–100

–200

–300

–400

1170/1/2 G12

VC PIN CURRENT (µA)

0 2.0

0.5 1.0 1.5 2.5

VFB = 1.5V (CURRENT INTO VC PIN)

VFB = 0.8V (CURRENT OUT OF VC PIN)

TJ = 25°C

TEMPERATURE (°C)

IDLE SUPPLY CURRENT (mA)

1170/1/2 G13

–75 –25 25 50 150

–50 0 75 100 125

VSUPPLY = 60V

VSUPPLY = 3V

VC = 0.6V

FEEDBACK CURRENT (mA)

FEEDBACK VOLTAGE (mV)

500

450

400

350

300

250

200

150

100

0.4

1170/1/2 G14

0.1 0.2 0.3 0.5 0.6 0.7 0.8 0.9 1.0

–55°C

25°C

150°C

SWITCH VOLTAGE (V)

SWITCH CURRENT (µA)

1000

900

800

700

600

500

400

300

200

100

1170/1/2 G15

10 20 30 50 60 70 80 90 100

VSUPPLY

= 55V

VSUPPLY

= 3V

VSUPPLY

= 15V

VSUPPLY

= 40V

TEMPERATURE (°C)

VC PIN VOLTAGE (mV)

1170/1/2 G16

400

350

300

250

200

150

100

–75 –25 25 50 150

–50 0 75 100 125

–400

–350

–300

–250

–200

–150

–100

–50

VC PIN CURRENT (µA)

CURRENT (OUT OF VC PIN)

VOLTAGE

VC VOLTAGE IS REDUCED UNTIL

REGULATOR CURRENT DROPS

BELOW 300µA

JUNCTION TEMPERATURE (°C)

–75

TIME (µs)

–25 25 50 150

1170/1/2 G17

–50 0 75 100 125

2.2

2.0

1.8

1.6

1.4

1.2

1.0

TEMPERATURE (°C)

FLYBACK VOLTAGE (V)

1170/1/2 G18

–75 –25 25 50 150

–50 0 75 100 125

RFB = 500Ω

RFB = 1k

RFB = 10k

LT1170/LT1171/LT1172

117012fg

TYPICAL PERFORMANCE CHARACTERISTICS

BLOCK DIAGRAM

FREQUENCY (Hz)

TRANSCONDUCTANCE (µmho)

7000

6000

5000

4000

3000

2000

1000

–1000 10k 100k

1170/1/2 G19

1M 10M

–30

120

150

180

210

PHASE (DEG)

TEMPERATURE (°C)

–50

FEEDBACK PIN VOLTAGE (mV)

500

490

480

470

460

450

440

430

420

410

400 050 75

1170/1/2 G20

–25 25 100 125 150

–24

–22

–20

–18

–16

–14

–12

–10

–8

–6

–4

FEEDBACK PIN CURRENT (µA)

FEEDBACK PIN CURRENT

(AT THRESHOLD)

FEEDBACK PIN VOLTAGE

(AT THRESHOLD)

Transconductance of Error

Amplifier

Normal/Flyback Mode Threshold on

Feedback Pin

1.24V

REF

1170/1/2 BD

ERROR

AMP

100kHz

OSC

2.3V

REG

VIN

–

SHUTDOWN

CIRCUIT

COMP

LOGIC DRIVER

ANTI-

SAT

FLYBACK

ERROR

AMP

16V

SWITCH

OUT

5A, 75V

SWITCH

0.02Ω

(0.04Ω

(0.16Ω

LT1171)

LT1172)

0.16Ω

CURRENT

AMP

GAIN 6

≈

0.15V

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.

†

MODE

SELECT

E1†E2

(LT1170 AND LT1171 ONLY)

LT1172

LT1170/LT1171/LT1172

117012fg

OPERATION

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. 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 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 LT1170/LT1171/LT1172 will

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.

A special delay network inside the LT1170/ LT1171/LT1172

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 func-

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 (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

LT1170/LT1171/LT1172 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

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. The miniDIPs, however, are rated at 100°C/W

in ceramic (J) and 130°C/W in plastic (N).

*See note under Block Diagram.

LT1170/LT1171/LT1172

117012fg

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:

IN ≈ 6mA + ISW (0.004 + DC/40)

SW = switch current

DC = switch duty cycle

Switch power dissipation is given by:

SW = (ISW)2 • (RSW)(DC)

SW = LT1172 switch “on” resistance (1 maximum)

Total power dissipation is the sum of supply current times

input voltage plus switch power:

D(TOT) = (IIN)(VIN) + PSW

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:

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

SW = (0.65)2 • (1)(0.6) = 0.25W

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

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

I2R switch dissipation under current limit conditions.

The fourth approach is to clamp the VC pin to a voltage

less than its internal clamp level of 2V. The LT1172 switch

current limit is zero at approximately 1V on the VC pin

and 2A at 2V on the VC pin. Peak switch current can be

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 VC pin is pulled to ground

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:

ΔVOS =

⎛

⎝

⎜⎞

⎠

⎟tS

(

)

(

)

IC+VC

⎛

⎝

⎜⎞

⎠

⎟

q=26mV at 25°C

C = pulse width

S = pulse frequency

C = VC source current (≈200µA)

C = operating VC voltage (1V to 2V)

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

frequency compensation network.

LT1170/LT1171/LT1172

117012fg

OPERATION

With tS = 0.2µs, fS = 150kHz, VC = 1.5V, and R3 = 2k, offset

voltage shift is ≈ 3.8mV. This is not particularly bother-

some, but note that high offsets could result if R3 were

reduced to a much lower value. Also, the synchronizing

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 VC pin to within 200mV of

ground to ensure synchronizing.

Synchronizing with Bipolar Transistor Synchronizing with MOS Transistor

1170/1/2 OP01

39pF R1

2.2k

LT1170

GND

VIN

R3 2N2369

FROM 5V

LOGIC

1170/1/2 OP02

1N4158

2.2k

LT1170

GND

VIN

FROM 5V

LOGIC

100pF

1N4158

* SILICONIX OR EQUIVALENT

VN2222*

TYPICAL APPLICATIONS

Flyback Converter

1170/1/2 TA03

2000µF

C4*

100µF

0.15µF

3.74k

1.24k

VIN

20V TO 30V

1.5k

*REQUIRED IF INPUT LEADS ≥ 2"

LT1170

VIN

VSW

OPTIONAL

FILTER

5µH

100µF

VOUT

VSNUB

CLAMP TURN-ON

SPIKE

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

VOUT + Vf

VIN

VOUT + Vf

N • VIN

$IIPRI

IPRI/N

IPRI

t = (IPRI)(LL)

VSNUB

N* = 1/3

25V

MUR110

GND

LT1170/LT1171/LT1172

117012fg

TYPICAL APPLICATIONS

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

LCD Contrast Supply

0.047µF

VOUT

–10V TO –26V

1170/1/2 TA04

15k

OPTIONAL

SHUTDOWN

100k

200k

1µF

TANTALUM

1N914

0.0047µF

C2***

2µF

TANTALUM

VN2222

5V* L1**

50µH VBAT*

3V TO 20V

VIN

VSW

LT1172

GND

***

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

VIN AND BATTERY MAY BE TIED TOGETHER. MAXIMUM VALUE FOR VBAT IS EQUAL TO THE |NEGATIVE OUTPUT|+ 1V. WITH HIGHER

BATTERY VOLTAGES, HIGHEST EFFICIENCY IS OBTAINED BY RUNNING THE LT1172 VIN PIN FROM 5V. SHUTTING OFF THE 5V SUPPLY

WILL AUTOMATICALLY TURN OFF THE LT1172. EFFICIENCY IS ABOUT 80% AT IOUT = 25mA.

R1, R2, R3 ARE MADE LARGE TO MINIMIZE BATTERY DRAIN IN SHUTDOWN, WHICH IS APPROXIMATELY VBAT /(R1 + R2 + R3).

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

600mA AT POUT = 0.7Ω. INDUCTOR SERIES RESISTANCE SHOULD BE LESS THAN 0.4Ω FOR HIGH EFFICIENCY.

OUTPUT RIPPLE IS ABOUT 200mVP-P TO 400mVP-P WITH C2 = 2µF TANTALUM. IF LOWER RIPPLE IS DESIRED, INCREASE C2, OR ADD

A 10Ω, 1µF TANTALUM OUTPUT FILTER.

Driving High Voltage FET

(for Off-Line Applications, See AN25)

External Current Limit

1170/1/2 TA05

VIN VSW

LT1170

GND

10V TO

20V

GQ1

1170/1/2 TA06

LT1170

GND

≈ 2V VC

500Ω

LT1170/LT1171/LT1172

117012fg

TYPICAL APPLICATIONS

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

Negative-to-Positive Buck-Boost Converter†External Current Limit

Negative Buck Converter

C4*

100µF

VOUT

12V

1170/1/2 TA07

2.2k

1000µF

0.22µF

VIN

VSW

LT1170

GND

OPTIONAL

INPUT FILTER

VIN

–20V

REQUIRED IF INPUT LEADS ≥ 2"

PULSE ENGINEERING 92114, COILTRONICS 50-2-52

1.24k

L1**

50µH

OPTIONAL

OUTPUT

FILTER

11.3k

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.

†

1170/1/2 TA08

VIN

VSW

LT1170

GND

VIN

NOTE THAT THE LT1170

GND PIN IS NO LONGER

COMMON TO VIN–.

–

1000pF

C3*

100µF

–5.2V

4.5A

1170/1/2 TA09

L1**

50µH

4.64k

1000µF

2N3906

VIN

VSW

LT1170

GND

OPTIONAL

INPUT FILTER

VIN

–20V

LOAD

REQUIRED IF INPUT LEADS ≥ 2"

PULSE ENGINEERING 92114

COILTRONICS 50-2-52

1.24k

12k

OPTIONAL

OUTPUT

FILTER

200µF

LT1170/LT1171/LT1172

117012fg

TYPICAL APPLICATIONS

Positive-to-Negative Buck-Boost Converter

1µF

VIN

10V TO

30V

1170/1/2 TA10

100µF*

D3†

1N4001

0.1µF

VIN

VSW

LT1170

GND

VOUT

–12V

REQUIRED IF INPUT LEADS ≥ 2"

PULSE ENGINEERING 92114, COILTRONICS 50-2-52

1.24k

L1**

50µH

R5†

470Ω, 1W

TO AVOID STARTUP PROBLEMS FOR INPUT VOLTAGES

BELOW 10V, CONNECT ANODE OF D3 TO VIN, AND

REMOVE R5. C1 MAY BE REDUCED FOR LOWER OUTPUT

CURRENTS. C1 ≈ (500µF)(IOUT).

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

0.3µF, AND REDUCE R6 TO 100Ω.

†

2µF

1N914 R4

47Ω

C1†

1000µF

470Ω

10.7k

+ +

High Efficiency Constant Current Charger

MBR340

1170/1/2 TA11

INPUT VOLTAGE

> VBAT + 2V < 35V

2.2µF

35V

TANTALUM

22k

0.47µF

V+

V–

200µF

25V BATTERY

2V TO 25V

L2*

10µH, 1A

100µH, 1A

0.05Ω

25k

RUN = 0V

SHUTDOWN = 5V

* L2 REDUCES RIPPLE CURRENT INTO

THE BATTERY BY ABOUT 20:1.

IT MAY BE OMITTED IF DESIRED.

I = 1.244V • R4

R3 • R5 = 1A AS SHOWN

CHRG

78k

VIN

VFB

VSW

GND

1N5819

0.01µF

LT1006

–

LT1171

200µF

35V

2N3904

+ +

GND

2µF

1170/1/2 TA12

1N914

33pF

3kV

10µF

TANT

10k

50k

INTENSITY

ADJUST

1N5818 L1**

300µH

INPUT VOLTAGE†

4.5V TO 20V

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.

***

†

1µF

560Ω

LT1172

VSW

1N914

LAMP

L2***

0.02µF

Q1*

Q2*

Backlight CCFL Supply (see AN45 for details)

LT1170/LT1171/LT1172

117012fg

TYPICAL APPLICATIONS

Positive Buck Converter

C5*

100µF

VIN

1170/1/2 TA13

470Ω

5V, 4.5A

1N914

1µF

VIN

VSW

LT1170

GND

REQUIRED IF INPUT LEADS ≥ 2"

PULSE ENGINEERING 92114

COILTRONICS 50-2-52

3.74k

L1**

50µH

10Ω

2.2µF

1.24k

1µF

1000µF

100mA

MINIMUM

OPTIONAL

OUTPUT

FILTER

200µF

4µH

Negative Boost Regulator

C4*

470µF

1170/1/2 TA14

3.3k

10µF

0.22µF

VIN

LT1170

GND

VIN

–15V

REQUIRED IF INPUT LEADS ≥ 2"

1.24k

27k

VSW

50µH

1000µF

(MINIMUM

LOAD)

VOUT

–28V, 1A

+ +

Driving High Voltage NPN

1170/1/2 TA15

SETS IB (ON)

SETS IB(OFF)

R2**

VIN

VSW

LT1170

GND

R1*

LT1170/LT1171/LT1172

117012fg

TYPICAL APPLICATIONS

Forward Converter

1170/1/2 TA16

2000µF

1.24k

VIN

20V TO 30V

LT1170

VIN

VSW

25µH

330Ω

1Ω

C2 M

D1 VOUT

5V, 6A

3.74k

GND

High Efficiency 5V Buck Converter

VSW

GND

VIN

LT1170

+C1

330µF

35V

0.02µF

0.1µF

680Ω C5

0.03µF

MBR330p

4.7µF

TANT

1N4148

50µH R2*

0.013Ω

390µF

16V

VOUT

3A**

MODE LOGIC

220pF

<0.3V = NORMAL MODE

>2.5V = SHUTDOWN

OPEN = BURST MODE

* R2 IS MADE FROM PC BOARD

COPPER TRACES.

** MAXIMUM CURRENT IS DETERMINED

BY THE CHOICE OF LT1070 FAMILY.

SEE APPLICATION SECTION.

VIN

1170/1/2 TA17

OPTIONAL

OUTPUT

FILTER

100µF

16V

10µH

GND

MODE

DIODE

VOUT

VLIM

V+

LT1432

VIN

LT1170/LT1171/LT1172

117012fg

PACKAGE DESCRIPTION

J8 Package

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

(Reference LTC DWG # 05-08-1110)

J8 0801

.014 – .026

(0.360 – 0.660)

.200

(5.080)

MAX

.015 – .060

(0.381 – 1.524)

.125

3.175

MIN

.100

(2.54)

BSC

.300 BSC

(7.62 BSC)

.008 – .018

(0.203 – 0.457) 0° – 15°

.005

(0.127)

MIN

.405

(10.287)

MAX

.220 – .310

(5.588 – 7.874)

1234

.025

(0.635)

RAD TYP

.045 – .068

(1.143 – 1.650)

FULL LEAD

OPTION

.023 – .045

(0.584 – 1.143)

HALF LEAD

OPTION

CORNER LEADS OPTION

(4 PLCS)

.045 – .065

(1.143 – 1.651)

NOTE: LEAD DIMENSIONS APPLY TO SOLDER DIP/PLATE

OR TIN PLATE LEADS

K Package

4-Lead TO-3 Metal Can

(Reference LTC DWG # 05-08-1311)

K4(TO-3) 0801

72o

18o

.490 – .510

(12.45 – 12.95)

.470 TP

P.C.D.

.167 – .177

(4.24 – 4.49)

.151 – .161

(3.84 – 4.09)

DIA 2 PLC

.655 – .675

(16.64 – 19.05)

1.177 – 1.197

(29.90 – 30.40)

.038 – .043

(0.965 – 1.09)

.060 – .135

(1.524 – 3.429)

.320 – .350

(8.13 – 8.89)

.420 – .480

(10.67 – 12.19)

.760 – .775

(19.30 – 19.69)

(OBSOLETE PACKAGE)

LT1170/LT1171/LT1172

117012fg

PACKAGE DESCRIPTION

N8 Package

8-Lead PDIP (Narrow .300 Inch)

(Reference LTC DWG # 05-08-1510)

N8 1002

.065

(1.651)

TYP

.045 – .065

(1.143 – 1.651)

.130 ± .005

(3.302 ± 0.127)

.020

(0.508)

MIN

.018 ± .003

(0.457 ± 0.076)

.120

(3.048)

MIN

12 34

87 65

.255 ± .015*

(6.477 ± 0.381)

.400*

(10.160)

MAX

.008 – .015

(0.203 – 0.381)

.300 – .325

(7.620 – 8.255)

.325 +.035

–.015

+0.889

–0.381

8.255

()

NOTE:

1. DIMENSIONS ARE INCHES

MILLIMETERS

*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.

MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED .010 INCH (0.254mm)

.100

(2.54)

BSC

LT1170/LT1171/LT1172

117012fg

PACKAGE DESCRIPTION

Q Package

5-Lead Plastic DD Pak

(Reference LTC DWG # 05-08-1461)

Q(DD5) 0502

.028 – .038

(0.711 – 0.965)

TYP

.143 +.012

–.020

()

3.632 +0.305

–0.508

.067

(1.702)

BSC

.013 – .023

(0.330 – 0.584)

.095 – .115

(2.413 – 2.921)

.004 +.008

–.004

()

0.102 +0.203

–0.102

.050 ± .012

(1.270 ± 0.305)

.059

(1.499)

TYP

.045 – .055

(1.143 – 1.397)

.165 – .180

(4.191 – 4.572)

.330 – .370

(8.382 – 9.398)

.060

(1.524)

TYP

.390 – .415

(9.906 – 10.541)

15° TYP

.420

.350

.565

.090

.042

.067

RECOMMENDED SOLDER PAD LAYOUT

.325

.205

.080

.565

.090

RECOMMENDED SOLDER PAD LAYOUT

FOR THICKER SOLDER PASTE APPLICATIONS

.042

.067

.420

.276

.320

NOTE:

1. DIMENSIONS IN INCH/(MILLIMETER)

2. DRAWING NOT TO SCALE

.300

(7.620)

.075

(1.905)

.183

(4.648)

.060

(1.524)

.060

(1.524)

.256

(6.502)

BOTTOM VIEW OF DD PAK

HATCHED AREA IS SOLDER PLATED

COPPER HEAT SINK

LT1170/LT1171/LT1172

117012fg

PACKAGE DESCRIPTION

S8 Package

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

(Reference LTC DWG # 05-08-1610)

.016 – .050

(0.406 – 1.270)

.010 – .020

(0.254 – 0.508)× 45°

0°– 8° TYP

.008 – .010

(0.203 – 0.254)

SO8 0303

.053 – .069

(1.346 – 1.752)

.014 – .019

(0.355 – 0.483)

TYP

.004 – .010

(0.101 – 0.254)

.050

(1.270)

BSC

1234

.150 – .157

(3.810 – 3.988)

NOTE 3

8765

.189 – .197

(4.801 – 5.004)

NOTE 3

.228 – .244

(5.791 – 6.197)

.245

MIN .160 ±.005

RECOMMENDED SOLDER PAD LAYOUT

.045 ±.005

.050 BSC

.030 ±.005

TYP

INCHES

(MILLIMETERS)

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)

LT1170/LT1171/LT1172

117012fg

PACKAGE DESCRIPTION

SW Package

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

(Reference LTC DWG # 05-08-1620)

S16 (WIDE) 0502

NOTE 3

.398 – .413

(10.109 – 10.490)

NOTE 4

16 15 14 13 12 11 10 9

2345678

N/2

.394 – .419

(10.007 – 10.643)

.037 – .045

(0.940 – 1.143)

.004 – .012

(0.102 – 0.305)

.093 – .104

(2.362 – 2.642)

.050

(1.270)

BSC .014 – .019

(0.356 – 0.482)

TYP

0° – 8° TYP

NOTE 3

.009 – .013

(0.229 – 0.330)

.005

(0.127)

RAD MIN

.016 – .050

(0.406 – 1.270)

.291 – .299

(7.391 – 7.595)

NOTE 4

× 45°

.010 – .029

(0.254 – 0.737)

INCHES

(MILLIMETERS)

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)

.420

MIN

.325 ±.005

RECOMMENDED SOLDER PAD LAYOUT

.045 ±.005

1 2 3 N/2

.050 BSC

.030 ±.005

TYP

LT1170/LT1171/LT1172

117012fg

PACKAGE DESCRIPTION

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

T5 (TO-220) 0801

.028 – .038

(0.711 – 0.965)

.067

(1.70) .135 – .165

(3.429 – 4.191)

.700 – .728

(17.78 – 18.491)

.045 – .055

(1.143 – 1.397)

.095 – .115

(2.413 – 2.921)

.013 – .023

(0.330 – 0.584)

.620

(15.75)

TYP

.155 – .195*

(3.937 – 4.953)

.152 – .202

(3.861 – 5.131)

.260 – .320

(6.60 – 8.13)

.165 – .180

(4.191 – 4.572)

.147 – .155

(3.734 – 3.937)

DIA

.390 – .415

(9.906 – 10.541)

.330 – .370

(8.382 – 9.398)

.460 – .500

(11.684 – 12.700)

.570 – .620

(14.478 – 15.748)

.230 – .270

(5.842 – 6.858)

BSC

SEATING PLANE

* MEASURED AT THE SEATING PLANE

LT1170/LT1171/LT1172

117012fg

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 representa-

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

REVISION HISTORY

REV DATE DESCRIPTION PAGE NUMBER

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

(Revision history begins at Rev G)

LT1170/LT1171/LT1172

117012fg

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

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

LT 0410 REV G • PRINTED IN USA

RELATED PARTS

TYPICAL APPLICATION

Positive Current Boosted Buck Converter

1170/1/2 TA18

0.33µF

470Ω

VIN

28V

680Ω

LT1170

VIN

VSW

1: N

1.24k

0.47µF

VOUT

5V, 10A

N ≈ 0.25

1.24k

GND

C5*

100µF

470Ω

0.002µF

–

0.01µF

VIN

200pF

5k C2

5000µF

* REQUIRED IF INPUT LEADS ≥ 2"

LM308

PART NUMBER DESCRIPTION COMMENTS

LT1070/LT1071/LT1072 5A/2.5A/1.25A High Efficiency Switching Regulators 40kHz, VIN to 60V, VSW to 75V

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

LT1082 1A, High Voltage, High Efficiency Switching Regulator VIN to 75V, VSW to 100V, Telecom

LT1268/LT1268B 7.5A, 150kHz Switching Regulators VIN to 30V, VSW to 60V

LT1269/LT1271 4A High Efficiency Switching Regulators 100kHz/60kHz, VIN to 30V, VSW to 60V

LT1270/LT1270A 8A and 10A High Efficiency Switching Regulators 60kHz, VIN to 30V, VSW to 60V

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 ±VOUT

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

LT1374 4A, 500kHz Step-Down Switching Regulator Synchronizable, VIN to 25V

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, <100µVP-P Output Noise