LT1072

1072fc

1.25A High Efficiency

Switching Regulator

Available in MiniDiP, TO-220, and TO-3 Packages

Wide Input Voltage Range 3V to 60V

Low Quiescent Current--6mA

Internal 1.25A Switch

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

Can be Externally Synchronized

The LT

1072 is a monolithic high power switching

regulator. It 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
LT1072 to be built in a standard 5-pin TO-3 or TO-220
power package as well as the 8-pin miniDlP. This makes it
extremely easy to use and provides "bust proof" operation
similar to that obtained with 3-pin linear regulators.

The LT1072 operates with supply voltages from 3V to 60V,
and draws only 6mA quiescent current. It can deliver load
power up to 20 watts with no external power devices. By
utilizing current-mode switching techniques, it provides
excellent AC and DC load and line regulation.

The LT1072 has many unique features not found even on
the vastly more difficult to use low power control chips
presently available. It uses an adaptive anti-sat 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 LT1072, without the need for optocouplers or
extra transformer windings.

USER NOTE:

This data sheet is only intended to provide specifications, graphs, and a general functional
description of the LT1072. Application circuits are included to show the capability of the LT1072.
A complete design manual (AN-19) 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 LT1072 by factoring in the lower switch current rating.

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

FEATURES

DESCRIPTIO

Boost Converter (5V to 12V)

TYPICAL APPLICATIO

10.7k

1.24k

LT1072

GND

1µF

470µF

12V, 0.25A

*REQUIRED IF INPUT LEADS 2"

**PULSE ENGINEERING 52626

220µH**

25µF*

LT1072 · TA01

Maximum Output Power*

LT1072 · TA02

INPUT VOLTAGE (V)

*ROUGH GUIDE ONLY. BUCK MODE P

OUT

= 1A x V

OUT

MINIDIP OUTPUT POWER MAY BE LIMITED BY PACKAGE TEMPERATURE

RISE AT HIGH INPUT VOLTAGES OR HIGH DUTY CYCLES

POWER (W)

BUCK-BOOST

= 5V

BUCK-BOOST

= 30V

FLYBACK

ISOLATED

BOOST

Logic Supply 5V at 2.5A

5V Logic to ±15V Op Amp Supply

Offline Converter up to 50W

Battery Upconverter

Power lnverter (+ to ) or ( to +)

Fully Floating Multiple Outputs

Driver for High Current Supplies

APPLICATIO S

LT1072

1072fc

Supply Voltage
LT1072HV (See Note 1) ......................................... 60V
LT1072 (See Note 1) ............................................. 40V
Switch Output Voltage
LT1072HV ............................................................. 75V
LT1072 .................................................................. 65V
LT1072S8 .............................................................. 60V
Feedback Pin Voltage (Transient, 1ms) ................. ±15V
Operating Junction Temperature Range

LT1072HVM, LT1072M (OBSOLETE) .... 55°C to 150°C
LT1072HVC, LT1072C (Oper.)* ............ 0°C to 100°C
LT1072HVC, LT1072C (Sh. Ckt.)* ........ 0°C to 125°C
LT1072HVI ....................................... 40°C to 125°C

Storage Temperature Range ............... 65°C to 150°C
Lead Temperature (Soldering, 10 sec) ............... 300°C

*Includes LT1072S8

(Note 1)

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

Note 1: Minimum switch "on" time for the LT1072 in current limit is
0.7µsec. This limits the maximum input voltage during short-circuit
conditions,

in the buck and inverting modes only,

to 40V. Normal

(unshorted) conditions are not affected. If the LT1072 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:

R =

(t) (f) (V

) V

(LIMIT)

t = Minimum "on" time of LT1072 in current limit, 0.7µs
f = Operating frequency (40kHz)

= Forward voltage of external catch diode at I

(LIMIT)

= Current limit of LT1072 (2A)

= Internal series resistance of inductor

OBSOLETE PACKAGE

Consider the S8 or N8 Packages for Alternate Source

T PACKAGE

5-LEAD TO-220

JMAX

= 100

C/W,

= 8

C/W,

= 50

C/W

GND

FRONT VIEW

N PACKAGE

8-LEAD PDIP

JMAX

= 100

= 130

C/W

J PACKAGE

8-LEAD CERAMIC DIP

JMAX

= 150

= 100

C/W

TOP VIEW

GND

E2
V

E1
V

SW PACKAGE

16-LEAD PLASTIC SO WIDE

JMAX

= 100

= 130

C/W

NC
NC

GND

NC
NC
NC

NC
NC
E2
V

NC
NC

TOP VIEW

BOTTOM VIEW

K PACKAGE

4-LEAD TO-3 METAL CAN

JMAX

= 150

= 8

C/W,

= 35

C/W

JMAX

= 100

C*,

= 8

C/W,

= 35

C/W

CASE IS
GND

2
3

LT1072HVMK
LT1072MK
LT1072HVCK
LT1072CK

ORDER PART

NUMBER

ORDER PART

NUMBER

ORDER PART

NUMBER

ORDER PART

NUMBER

LT1072CT
LT1072HVCT
LT1072HVIT

LT1072CN8
LT1072CS8

LT1072MJ8
LT1072CJ8

LT1072CSW

LT1072 · POI01

TOP VIEW

GND

S8 PACKAGE

8-LEAD PLASTIC SO

JMAX

= 100

= 130

C/W

S8 PART

MARKING

1072

ABSOLUTE AXI U RATI GS

PACKAGE/ORDER I FOR ATIO

LT1072

1072fc

SYMBOL

PARAMETER

CONDITlONS

MIN

TYP

MAX

UNITS

REF

Reference Voltage

Measured at Feedback Pin

1.224

1.244

1.264

= 0.8V

1.214

1.244

1.274

Feedback Input Current

= V

REF

350

750

1100

Error Amplifier

= ±25µA

3000

4400

6000

µmho

Transconductance

2400

7000

µmho

Error Amplifier Source or

= 1.5V

150

200

350

µA

Sink Current

120

400

µA

Error Amplifier Clamp

Hi Clamp, V

= 1V

1.8

2.3

Voltage

Lo Clamp, V

= 1.5V

0.25

0.38

0.52

Reference Voltage Line

3V V

MAX

0.03

%/V

Regulation

= 0.8V

%/V

Error Amplifier Voltage Gain

0.9V V

1.4V

500

800

V/V

Minimum Input Voltage

2.6

3.0

Supply Current

3V V

MAX

, V

= 0.6V

Control Pin Threshold

Duty Cycle = 0

0.8

0.9

1.08

0.6

1.25

Normal/Flyback Threshold on Feedback Pin

0.4

0.45

0.54

Flyback Reference Voltage

= 50µA

16.3

17.6

Change in Flyback Reference Voltage

0.05 I

1mA

4.5

6.8

8.5

Flyback Reference Voltage

= 50µA

0.01

0.03

%/V

Line Regulation

3V V

MAX

(Note 4)

%/V

Flyback Amplifier Transconductance (gm)

= ±10µA

150

300

650

µmho

Flyback Amplifier Source

= 0.6V Source

µA

and Sink Current

= 50µA Sink

µA

Output Switch Breakdown

3V V

MAX

LT1072

Voltage

= 1.5mA

LT1072HV

LT1072S8

SAT

Output Switch ON Resistance (Note 2)

= 1.25A

0.6

Control Voltage to Switch Current Transconductance

A/V

LIM

Switch Current Limit

Duty Cycle = 50%

25°C

1.25

Duty Cycle = 50%

< 25°C

1.25

3.5

Duty Cycle = 80% (Note 3)

2.5

Supply Current Increase

mA/A

During Switch ON Time

Switching Frequency

kHz

DC (max)

Maximum Switch Duty Cycle

Flyback Sense Delay Time

1.5

µs

Shutdown Mode

3V V

MAX

100

250

µA

Supply Current

= 0.05V

Shutdown Mode

3V V

MAX

100

150

250

Threshold Voltage

300

The

denotes specifications which apply over the full operating

temperature range. Unless otherwise specified, V

= 15V, V

= 0.5V, V

= V

REF

, output pin open.

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

Note 2: Measured with V

in hi clamp, V

= 0.8V.

Note 3: For duty cycles (DC) between 50% and 80%, minimum
guaranteed switch current is given by I

LIM

= 0.833 (2 DC).

Note 4: V

MAX

= 55V for LT1072HV to avoid switch breakdown.

ELECTRICAL CHARACTERISTICS

LT1072

1072fc

Switch Current Limit vs Duty Cycle

Maximum Duty Cycle

Flyback Blanking Time

DUTY CYCLE (%)

SWITCH CURRENT (A)

LT1072 · TPC01

100

55°C

125°C

25°C

JUNCTION TEMPERATURE (°C)

DUTY CYCLE (%)

150

LT1072 · TPC02

75 100 125

JUNCTION TEMPERATURE (°C)

1.0

TIME (

1.2

1.6

1.8

2.0

150

LT1072 · TPC03

1.4

75 100 125

2.2

Minimum Input Voltage

Switch Saturation Voltage

Isolated Mode Flyback Reference
Voltage

TEMPERATURE (°C)

2.3

MINIMUM INPUT VOLTAGE (V) 2.4

2.6

2.7

2.8

150

LT1072 · TPC04

2.5

75 100 125

2.9

SWITCH CURRENT = 1.25A

SWITCH CURRENT = 0A

SWITCH CURRENT (A)

SWITCH SATURATION VOLTAGE (V)

0.8

1.2

LT1072 · TPC05

0.4

0.5

1.5

0.25

0.75

1.25

1.75

1.6

0.6

1.0

0.2

1.4

150°C

100°C

55°C

25°C

TEMPERATURE (C°)

FLYBACK VOLTAGE (V)

125

LT1072 · TPC06

150

100

FEEDBACK

= 500

FEEDBACK

= 1k

FEEDBACK

= 10k

Line Regulation

Reference Voltage and Switching
Frequency vs Temperature

Feedback Bias Current vs
Temperature

INPUT VOLTAGE (V)

REFERENCE VOLTAGE CHANGE (mV)

LT1072 · TPC07

= 150°C

= 55°C

= 25°

TEMPERATURE (°C)

REFERENCE VOLTAGE (V)

FREQUENCY (kHz)

1.242

1.244

1.246

125

LT1072 · TPC08

1.240

1.238

1.234

150

100

1.236

1.250

1.248

REFERENCE VOLTAGE

SWITCHING FREQUENCY

TEMPERATURE (°C)

FEEDBACK BIAS CURRENT (nA)

400

500

600

125

LT1072 · TPC09

300

200

150

100

800

700

TYPICAL PERFOR A CE CHARACTERISTICS

LT1072

1072fc

Driver Current* vs Switch Current

Supply Current vs Input Voltage*

Supply Current vs Supply Voltage
(Shutdown Mode)

Normal/Flyback Mode Threshold
on Feedback Pin

Shutdown Mode Supply Current

Error Amplifier Transconductance

Shutdown Thresholds

Idle Supply Current vs
Temperature

Feedback Pin Clamp Voltage

SWITCH CURRENT (A)

*AVERAGE LT1072 POWER SUPPLY CURRENT IS

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

DRIVER CURRENT (mA)

1.6

LT1072 · TPC10

0.4

0.8

1.2

1.4

0.2

0.6

1.8

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

INPUT VOLTAGE (V)

SUPPLY CURRENT (mA)

LT1072 · TPC11

= 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

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (

100

LT1072 · TPC12

120

140

160

= 25°C

= 50mV

= 0V

TEMPERATURE (°C)

400

FEEDBACK PIN VOLTAGE (mV)

FEEDBACK PIN CURRENT (

410

430

440

450

500

470

LT1072 · TPC13

420

480

490

460

100 125

150

FEEDBACK PIN VOLTAGE
(AT THRESHOLD)

FEEDBACK PIN CURRENT
(AT THRESHOLD)

PIN VOLTAGE (mV)

SUPPLY CURRENT (

120

160

200

LT1072 · TPC14

100

140

180

60 70

100

= 150°C

55°C T

125°C

TEMPERATURE (C°)

TRANSCONDUCTANCE (

mho)

500

1500

2000

2500

5000

3500

150

LT1072 · TPC15

1000

4000

4500

3000

75 100 125

PIN)

(FB PIN)

TEMPERATURE (°C)

PIN VOLTAGE (mV)

PIN VOLTAGE (

200

250

300

125

LT1072 · TPC16

150

100

150

100

400

350

200

250

300

150

100

400

350

CURRENT (OUT OF V

PIN)

VOLTAGE

VOLTAGE IS REDUCED UNTIL

REGULATOR CURRENT DROPS
BELOW 300µA

TEMPERATURE (°C)

IDLE SUPPLY CURRENT (mA)

150

LT1072 · TPC17

75 100 125

= 0.6V

SUPPLY

= 60V

SUPPLY

= 3V

FEEDBACK CURRENT (mA)

FEEDBACK VOLTAGE (mV)

300

400

500

0.8

LT1072 · TPC18

200

100

250

350

450

150

0.2

0.1

0.4

0.3

0.6 0.7

0.9

0.5

55°C

25°C

150°C

TYPICAL PERFOR A CE CHARACTERISTICS

LT1072

1072fc

Transconductance of Error
Amplifier

Pin Characteristics

Switch "Off" Characteristics

FREQUENCY (Hz)

1000

TRANSCONDUCTANCE (

mho)

PHASE (

)

3000

4000

6000

7000

100k

10M

LT1072 · TPC19

1000

10k

5000

2000

150

210

120

180

PIN VOLTAGE (V)

400

PIN CURRENT (

300

200

100

300

100

0.5

1.0

200

1.5

2.0

2.5

LT1072 · TPC20

= 1.5V (CURRENT INTO V

PIN)

= 0.8V (CURRENT OUT OF V

PIN)

= 25°C

SWITCH VOLTAGE (V)

SWITCH CURRENT (

600

800

1000

LT1072 · TPC21

400

200

500

700

900

300

100

60 70

100

SUPPLY

= 55V

SUPPLY

= 40V

SUPPLY

= 15V

SUPPLY

= 3V

2.3V

REG

40kHz

OSC

SHUTDOWN
CIRCUIT

0.15V

0.16

GAIN

GND

MODE

SELECT

LOGIC

COMP

FLYBACK

ERROR

AMP

DRIVER

ANTI-

SAT

SWITCH

OUT

16V

0.16

E1*

* ALWAYS CONNECT E1 TO GROUND PIN ON MINIDIP AND SURFACE MOUNT

PACKAGES. EMITTERS TIED TO GROUND ON TO-3 AND TO-220 PACKAGES

1.24V

REF

ERROR

AMP

CURRENT

AMP

LT1072 · BD01

TYPICAL PERFOR A CE CHARACTERISTICS

BLOCK DIAGRA

LT1072

1072fc

The LT1072 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 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 midfrequencies in the energy
storage inductor. This greatly simplifies closed loop fre-
quency 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 LT1072. 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 LT1072 to disconnect the main error
amplifier output and connects the output of the flyback
amplifier to the comparator input. The LT1072 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 LT1072 ignores the leakage inductance spike at
the leading edge of the flyback pulse to improve output
regulation.

The error signal developed at the comparator input is
brought out externally. This pin (V

) 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 V

pin is pulled to ground through

a diode, placing the LT1072 in an idle mode. Pulling the V

pin below 0.15V causes total regulator shutdown, with
only 50µA supply current for shutdown circuitry biasing.
See AN-19 for full application details.

Extra Pins on the MiniDIP and Surface Mount Packages

The 8 and 16-pin versions of the LT1072 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 100mA. 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."

Thermal Considerations When Using Small Packages

The low supply current and high switch efficiency of the
LT1072 allow it to be used without a heat sink in most
applications when the TO-220 or TO-3 package is selected.

These packages are rated at 50°C/W and 35°C/W
respectively. The small packages, however, are rated at
greater than 100°C/W. Care should be taken with these
packages to ensure that the worse case input voltage and
load current conditions do not cause excessive die
temperatures. The following formulas can be used as a

LT1072 OPERATIO

LT1072

1072fc

rough guide to calculate LT1072 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

(0.004 + DC/40)

= switch current

DC = switch duty cycle

Switch power dissipation is given by:

= (I

)

· R

· DC

= LT1072 switch "on" resistance (1 maximum)

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

TOT

= (l

)(V

) + P

In a typical example, using a boost converter to generate
12V @ 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

= (0.65)

· 1 · (0.6) = 0.25W

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
ambient 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 LT1072 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 non-critical 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 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 I

switch dissipation under current limit conditions.

The fourth approach is to clamp the V

pin to a voltage less

than its internal clamp level of 2V. The LT1072 switch
current limit is zero at approximately 1V on the V

pin and

2A at 2V on the V

pin. Peak switch current can be

externally clamped between these two levels with a diode.
See AN-19 for details.

LT1072 Synchronizing

The LT1072 can be externally synchronized in the frequency
range of 48kHz to 70kHz. This is accomplished as shown
in the accompanying figures. Synchronizing occurs when
the V

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 1µs. C2 sets the pulse width at 0.35µs.
The effect of a synchronizing pulse on the LT1072
amplifier offset can be calculated from:

= 26mV at 25°C

q
t

= pulse width

= pulse frequency

= LT1072 V

source current ( 200µA)

= LT1072 operating V

voltage (1V to 2V)

R3 = resistor used to set mid-frequency "zero" in LT1072

frequency compensation network.

With t

= 0.35µs, f

= 50kHz, V

= 1.5V, and R3 = 2K,

offset voltage shift is 2.2mV. This is not particularly
bothersome, 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 V

pin to within

200mV of ground to ensure synchronizing.

LT1072 OPERATIO

)(f

) I

(

LT1072

1072fc

Flyback Converter

Negative to Positive Buck-Boost Converter

External Current Limit

NOTE THAT THE LT1072 GND PIN
IS NO LONGER COMMON TO V

()

LT1072 · TA06

C1
1000pF

GND

LT1072

C3
0.47µF

OUT

5V
1.5A

OPTIONAL

FILTER

1
3

N* =

0.15µF

25µF*

20 TO 30V

R3
1.5k

REQUIRED IF INPUT LEADS 2"
OPTIONAL TO REPLACE R4 AND C3

C1
500µF

R4
1k

R1
3.74k

R2
1.24k

GND

LT1072

10µH

200µF

SNUB

OUT

+ V

PRI

) (L

)

SNUB

PRI

CLAMP TURN-ON

SPIKE

PRIMARY FLYBACK VOLTAGE =

LT1072 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

LT1070 SWITCH CURRENT

SNUBBER DIODE CURRENT

OUT

+ V

N · V

t =

LT1072 · TA04

GND

LT1072

1000µF

0.22µF

25µF*

R2
1.24k

R3
2.2k

R1
11.3k

OUT

12V, 0.5A

12V

L1**

220µH

REQUIRED IF INPUT LEADS 2"
PULSE ENGINEERING 52626

OPTIONAL

INPUT

FILTER

OPTIONAL

OUTPUT

FILTER

LT1072 · TA05

TYPICAL APPLICATIO S

LT1072

1072fc

Positive to Negative Buck-Boost Converter

External Current Limit

LT1072 · TA08

500

GND

LT1072

Voltage Boosted Boost Converter

LT1072 · TA09

TOTAL INDUCTANCE = 8mH
INTERLEAVE PRIMARY AND
SECONDARY FOR LOW LEAKAGE
INDUCTANCE

1
L1
N = 5

0.047µF

R3
10k

15V

C1
200µF

1.5k

1/2W

0.68

98k

OUT

100V AT 75mA

R2
1.24k

GND

LT1072

100µF*

10 TO 30V

*REQUIRED IF INPUT LEADS 2"

**PULSE ENGINEERING 92113

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

AND REMOVE R5. C1 MAY BE
REDUCED FOR LOWER OUTPUT
CURRENTS. C1 (500µF)(I

OUT

FOR 5V OUTPUTS, REDUCE R3
TO 1.5k, INCREASE C2 TO 0.3µF,
AND REDUCE R6 TO 100

LT1072 · TA07

1N914

1000µF

C3
2µF

470, 1W

C2
0.1µF

1N4001

5µF

R6
470

R2
1.24k

L1**
200µH

R3
5k

OUT

12V AT 2A

10.7k

GND

LT1072

TYPICAL APPLICATIO S

LT1072

1072fc

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)

.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

Negative Boost Regulator

J8 Package

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

(Reference LTC DWG # 05-08-1110)

LT1072 · TA13

*REQUIRED IF INPUT LEADS 2"

C2
0.22µF

R3
3.3k

470µF*

15V

C3
10µF

C1
1000µF

R1
27k

R2
1.24k

(MINIMUM
LOAD)

OUT

28V AT 0.25A

200µH

GND

LT1072

OBSOLETE PACKAGE

TYPICAL APPLICATIO S

PACKAGE DESCRIPTIO

LT1072

1072fc

K Package

4-Lead TO-3 Metal Can

(Reference LTC DWG # 05-08-1311)

OBSOLETE PACKAGE

K4(TO-3) 1098

72°

18°

0.490 0.510

(12.45 12.95)

0.470 TP

P.C.D.

0.167 0.177

(4.24 4.49)

0.151 0.161

(3.84 4.09)

DIA 2 PLC

0.655 0.675

(16.64 19.05)

1.177 1.197

(29.90 30.40)

0.038 0.043

(0.965 1.09)

0.060 0.135

(1.524 3.429)

0.320 0.350

(8.13 8.89)

0.420 0.480

(10.67 12.19)

0.760 0.775

(19.30 19.69)

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

.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

PACKAGE DESCRIPTIO

LT1072

1072fc

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

SW Package

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

(Reference LTC DWG # 05-08-1620)

S8 Package

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

(Reference LTC DWG # 05-08-1610)

PACKAGE DESCRIPTIO

.016 .050

(0.406 1.270)

.010 .020

(0.254 0.508)

× 45°

0° 8° TYP

.008 .010

(0.203 0.254)

SO8 0502

.053 .069

(1.346 1.752)

.014 .019

(0.355 0.483)

TYP

.004 .010

(0.101 0.254)

.050

(1.270)

BSC

N/2

.150 .157

(3.810 3.988)

NOTE 3

.189 .197

(4.801 5.004)

NOTE 3

.228 .244

(5.791 6.197)

.245
MIN

N/2

.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)

S16 (WIDE) 0502

NOTE 3

.398 .413

(10.109 10.490)

NOTE 4

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

N/2

.050 BSC

.030 ±.005

TYP

LT1072

1072fc

LW/TP 1102 1K REV C · PRINTED IN USA

LINEAR TECHNOLOGY CORPORATION 1988

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900

FAX: (408) 434-0507

www.linear.com

PART NUMBER

DESCRIPTION

COMMENTS

LT1070/HV

5A I

, 40kHz, High Efficiency Switching Regulator

=3V to 40/60V, V

OUT

up to 65/75V, I

=6mA, I

<50µA, TO220-5

Package

LT1071/HV

2.5A I

, 40kHz, High Efficiency Switching Regulator

=3V to 40/60V, V

OUT

up to 65/75V, I

=6mA, I

<50µA,TO220-5 Package

LT1082

1A I

, 60kHz, High Efficiency Switching Regulator

=3V to 75V, V

OUT

up to 100V, I

=4.5mA, I

<120µA, DD, N8, TO220-5

Packages

LT1170/HV

5A I

, 100kHz, High Efficiency Switching Regulator

=3V to 40/60V, V

OUT

up to 65/75V, I

=6mA, I

<50µA, DD, N8, S16,

TO220-5 Packages

LT1171/HV

2.5A I

, 100kHz, High Efficiency Switching

=3V to 40/60V, V

OUT

up to 65/75V, I

=6mA, I

<50µA, DD, N8, S16,

Regulator

TO220-5 Packages

LT1172/HV

1.25A I

, 100kHz, High Efficiency Switching

=3V to 40/60V, V

OUT

up to 65/75V, I

=6mA, I

<50µA, DD, N8, S16,

Regulator

TO220-5 Packages

LT1307/LT1307B

600mA I

, 600kHz, High Efficiency Switching

=1V to 12V, V

OUT

up to 28V, I

=50µA/1mA, I

<1µA, MS8, N8, S8

Regulator

Packages

LT1317/LT1317B

600mA I

, 600kHz, High Efficiency Switching

=1.5V to 12V, V

OUT

up to 28V, I

=100µA/4.8mA, I

<30µA/28µA, MS8,

Regulator

S8 Packages

LT1370/HV

6A ISW, 500kHz, High Efficiency Switching Regulator

=2.7V to 30V, V

OUT

up to 35/42V, I

=4.5mA, I

<12µA, DD, T0220-7

Packages

LT1371/HV

3A ISW, 500kHz, High Efficiency Switching Regulator

=2.7V to 30V, V

OUT

up to 35/42V, I

=4mA, I

<12µA, DD, S20,

T0220-7 Packages

T Package

5-Lead Plastic TO-220 (Standard)

(Reference LTC DWG # 05-08-1421)

PACKAGE DESCRIPTIO

RELATED PARTS

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

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LT1072M

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: LT1072M