Linear Technology LT1105IN8, LT1105IN, LT1105CN8, LT1105CN, LT1103CT7 Datasheet

OBSOLETE:

FOR INFORMATION PURPOSES ONLY

Contact Linear Technology for Potential Replacement

FEATURES

■

±1% Line and Load Regulation with No Optocoupler

■

Switch Frequency Up to 200kHz

■

Internal 2A Switch and Current Sense (LT1103)

■

Internal 1A Totem-Pole Driver (LT1105)

■

Start-Up Mode Draws Only 200µA

■

Fully Protected Against Overloads

■

Overvoltage Lockout of Main Supply

■

Protected Against Underdrive or Overdrive to FET

■

Operates in Continuous or Discontinuous Mode

■

Ideal for Flyback and Forward Topologies

■

Isolated Flyback Mode Has Fully Floating Outputs

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APPLICATIONS

■

Up to 250W Isolated Mains Converter

■

Up to 50W Isolated Telecom Converter

■

Fully Isolated Multiple Outputs

■

Distributed Power Conversion Networks

LT1103/LT1105

Offline Switching Regulator

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DESCRIPTION

The LT®1103 Offline Switching Regulator is designed for
high input voltage applications using an external FET
switch whose source is driven by the open collector output
of the LT1103. The LT1103 is optimized for 15W to 100W
applications. For higher power applications or additional
switch current flexibility, the LT1105 is available and its
totem pole output drives the gate of an external FET.
Unique design of the LT1103/LT1105 eliminates the need
for an optocoupler while still providing ±1% load and line
regulation in a magnetic flux-sensed converter. This sig­nificantly simplifies the design of offline power supplies
and reduces the number of components which must cross
the isolation barrier to one, the transformer.

The LT1103/LT1105 current mode switching techniques
are well suited to transformer isolated flyback and forward
topologies while providing ease of frequency compensa­tion with a minimum of external components. Low exter­nal part count for a typical application combines with a

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

TYPICAL APPLICATION

Fully Isolated Flyback 100kHz 50W Converter with Load Regulation Compensation

85V

TO 270V

AC

AC

+

–

BRIDGE

RECTIFIER

+

LINE

FILTER

+

220µF
385V

BAV21

13k
1%

4.75k
1%

499Ω

1000pF

18.7k

0.047µF

100Ω

BAV21

1N4148

Danger!! Lethal Voltages Present – See Text

39µF

35V

+

220k
1W

0.047µF

V

FB
GND

IN

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DANGER!!

HIGH VOLTA

1N4148

V

SW

LT1103

15V

V

OSC

C

330Ω

0.1µF

G

390pF

E!!

1.5KE300A
5W

MUR150

BUK426-800A

10Ω

+

1µF
25V

OPTIONAL OUTPUT FILTER

MBR2045

*OUTPUT CAPACITOR IS THREE 1200µF,
50V CAPACITORS IN PARALLEL TO
ACHIEVE REQUIRED RIPPLE CURRENT
RATING AND LOW ESR.

TRANSFORMER DATA:
COILTRONICS CTX110228-3
L

= 1.6mH

(PRI)

N

PRI:NSEC

N

BIAS:NSEC

LT1103 TA13

+

*50V
3600µF

WINDINGS FOR
OPTIONAL

OUTPUTS

±12V

DC

= 1:0.05

= 1:0.27

10µH

+

50V
470µF

5V
10A

Load Regulation

5.25

5.20

5.15

5.10

5.05

(V)

5.00

OUT

V

4.95

4.90

4.85

4.80

4.75
0

270V

2

3

1

220V

AC

110V

AC

AC

579

6

4

I

OUT

8

(A)

85V

AC

LT1103 TA02

10

1

LT1103/LT1105

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DESCRIPTION

200kHz maximum switching frequency to achieve high
power density. Performance at switching frequencies
above 100kHz may be degraded due to internal timing
constraints associated with fully isolated flyback mode.

Included are the oscillator, control, and protection cir­cuitry such as current limit and overvoltage lockout.
Switch frequency and maximum duty cycle are adjustable.
Bootstrap circuitry draws 200µA for start-up of isolated
topologies. A 5V reference as well as a 15V gate bias are
available to power external primary-side circuitry. No
external current sense resistor is necessary with LT1103
because it is integrated with the high current switch. The
LT1105 brings out the input to the current limit amplifier
and requires the use of an external sense resistor.

The LT1103/LT1105 have unique features not found on
other offline switching regulators. Adaptive antisat switch
drive allows wide ranging load currents while maintaining
high efficiency. The external FET is protected from insuf­ficient or excessive gate drive voltage with a drive detec­tion circuit. An externally activated shutdown mode
reduces total supply current to less than 200µA, typical for
standby operation. Fully isolated and regulated outputs
can be generated in the optional isolated flyback mode
without the need for optocouplers or other isolated feed­back paths.

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WAR I G!

DANGEROUS AND LETHAL POTENTIALS ARE
PRESENT IN OFFLINE CIRCUITS!

BEFORE PROCEEDING ANY FURTHER, THE
READER IS WARNED THAT CAUTION MUST
BE USED IN THE CONSTRUCTION, TESTING
AND USE OF OFFLINE CIRCUITS. HIGH
VOLTAGE, AC LINE-CONNECTED POTENTIALS
ARE PRESENT IN THESE CIRCUITS. EXTREME
CAUTION MUST BE USED IN WORKING WITH
AND MAKING CONNECTIONS TO THESE
CIRCUITS. REPEAT: OFFLINE CIRCUITS
CONTAIN DANGEROUS, AC LINE-CONNECTED
HIGH VOLTAGE POTENTIALS. USE CAUTION.

ALL TESTING PERFORMED ON AN OFFLINE
CIRCUIT MUST BE DONE WITH AN ISOLATION
TRANSFORMER CONNECTED BETWEEN THE
OFFLINE CIRCUIT'S INPUT AND THE AC LINE.
USERS AND CONSTRUCTORS OF OFFLINE
CIRCUITS MUST OBSERVE THIS PRECAUTION
WHEN CONNECTING TEST EQUIPMENT TO
THE CIRCUIT TO AVOID ELECTRIC SHOCK.
REPEAT: AN ISOLATION TRANSFORMER
MUST BE CONNECTED BETWEEN THE CIRCUIT
INPUT AND THE AC LINE IF ANY TEST
EQUIPMENT IS TO BE CONNECTED.

WW

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ABSOLUTE MAXIMUM RATINGS

VIN.......................................................................... 30V

V

Output Voltage (LT1103)................................. 50V

SW

VSW Output Current (200ns)(LT1105) ................. ±1.5A

VC, FB, OSC, SS ........................................................ 6V

I

(LT1105) ........................................................... 3V

LIM

0VLO Input Current ............................................... 1mA

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

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(Note 1)

2

Maximum Operating Ambient Temperature Range

LT1103C .............................................. 0°C to 70°C

LT1105C .............................................. 0°C to 70°C

Maximum Operating Junction Temperature Range

LT1103C ............................................. 0°C to 100°C

LT1105C ............................................ 0°C to 100°C

LT1105I ......................................... –40°C to 125°C

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

LT1103/LT1105

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PACKAGE/ORDER INFORMATION

ORDER PART

NUMBER

TOP VIEW

PWRGND

1
2

OVLO

3

FB

4

V

C

5

5V

6

SS

7

GND

N PACKAGE

14-LEAD PDIP

PINS 1 AND 7 MUST BE TIED TOGETHER

T

= 100°C, θJA = 100°C/W

JMAX

V

14

SW

NC

13

NC

12

15V

11

V

10

IN

OSC

9

I

8

LIM

Consult factory for Military grade parts.

LT1105CN
LT1105IN

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TOP VIEW

GND

1

I

2

LIM

3

FB

45

V

C

N8 PACKAGE
8-LEAD PDIP

T

= 100°C, θJA = 130°C/W

JMAX

FRONT VIEW

7
6
5
4
3
2
1

T7 PACKAGE

CASE IS CONNECTED TO GROUND. LEADS ARE FORMED

7-LEAD TO-220

= 100°C, θJA = 50°C/W

T

JMAX

ORDER PART

8

V

SW

15V

7
6

V

IN

OSC

NUMBER

LT1105CN8
LT1105IN8

ORDER PART

15V
V

IN

OSC
GND
V

C

FB
V

SW

NUMBER

LT1103CT7

ELECTRICAL CHARACTERISTICS

VIN = 20V, VC = 0.85V, OVLO = 0V, VSW Open, TA = 25°C, unless otherwise noted.

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

I

Q

I

START

V

REF

V

GATE

SF Oscillator Scaling Factor FB = 4V, VC = Open, Measured at VSW, ISW = 25mA, 36 40 44 Hz • µF

Supply Current 8V < VIN < 30V, After Device Has Started ● 10 20 30 mA
Start-Up Current VIN < VIN Start Threshold ● 200 400 µA

Industrial Grade

● 450 µA

VIN Start Threshold ● 14.5 16.0 17.5 V
VIN Shutdown Threshold Note: Switching Stops When VSW < 10V (LT1103) ● 5.0 7.0 8.0 V

Note: Switching Stops When V

< 10V (LT1105)

GATE

5V Reference Voltage ● 4.80 4.95 5.20 V
V

Line Regulation 10V < VIN < 30V ● 0.025 0.1 %/ V

REF

V

Load Regulation 0mA < IL < 20mA ● 0.025 0.05 %/mA

REF

V

Short-Circuit Current Commercial Grade ● 25 60 110 mA

REF

Industrial Grade

● 20 120 mA

15V Short-Circuit Current Commercial Grade ● 30 130 mA

Industrial Grade

● 25 140 mA

15V Gate Bias Reference 17 < VIN < 30V, 0mA < IL < 30mA ● 13.8 15.0 16.2 V
15V Dropout Voltage VIN = 15V, IL = 30mA ● 2.0 2.5 V
15V Short-Circuit Current ● 30 70 130 mA

OVLO = 5V, f

OSC

= SF/C

OSC,

40kHz < f

< 200kHz ● 32 40 48 Hz • µF

OSC

Oscillator Valley Voltage 2.0 V
Oscillator Peak Voltage 4.5 V

3

LT1103/LT1105

ELECTRICAL CHARACTERISTICS

VIN = 20V, VC = 0.85V, OVLO = 0V, VSW Open, TA = 25°C, unless otherwise noted.

SYMBOL PARAMETER CONDITONS MIN TYP MAX UNIT

DC Preset Max Switch Duty Cycle FB = 4V, VC = Open, f

(LT1103) Note: Maximum Duty Cycle Can Be Altered at OSC Pin
Preset Max Switch Duty Cycle FB = 4V, VC = Open, f

(LT1105) Note: Maximum Duty Cycle Can Be Altered at OSC Pin

Industrial Grade ● 55 75 %

OVLO Threshold Overvoltage Lockout Threshold at Which Switching is Inhibited ● 2.3 2.5 2.7 V

Industrial Grade

OVLO Input Bias Current OVLO = 2V, Measured Out of Pin (Note 2) ● 1.0 3.0 µA

V

FB

gm Error Amp Transconductance ∆I(VC) = ±50µA 9000 12000 17500 µmho

A

V

BV Switch Breakdown Voltage ISW = 5mA ● 50 70 V

∆I

IN

∆I

SW

FB Threshold Voltage I(VC) = 0mA 4.425 4.50 4.575 V

FB Input Bias Current FB = VFB (Note 3) ● 51020 µA

Industrial Grade

Change in FB Input FB = VFB, VC = 1V to 4V (Note 3) 8 11 13 µA/V
Bias Current with Change in V

FB Threshold Line Regulation 10V < VIN < 30V ● 0.025 0.10 %/V

Error Amp Voltage Gain 1V < VC < 3V ● 500 1250 V/V

VC Switching Threshold Switch Duty Cycle = 0% ● 0.85 1.25 1.4 V
Shutdown Threshold Voltage ● 50 150 250 mV

Error Amp Source Current ● 150 275 µA
Error Amp Sink Current ● 1.5 3 4.5 mA

Error Amp Clamp Voltage FB = 4.75V ● 0.3 0.7 0.9 V

Soft-Start Charging Current SS = 0V ● 25 40 60 µA

Soft-Start Reset Current VIN = 6V, SS = 0.3V ● 12 mA
Output Switch Leakage VSW = 45V ● 500 µA

(LT1103) V

(LT1103)
VSW Current Limit (LT1103) Duty Cycle = 25% (Note 4) ● 2.0 2.5 3.0 A
Output Switch On Resistance ● 0.4 0.75 Ω

(LT1103)
IQ Increase During Switch On Time ISW = 0.5A to 1.5A ● 30 50 mA/A

(LT1103)
Switch Output High Level ISW = 200mA, V

(LT1105) I
Switch Output High Level I
Industrial Grade I

C

Industrial Grade

Industrial Grade

Industrial Grade

Industrial Grade

Industrial Grade

FB = 4.0V

Industrial Grade

= 15V ● 200 µA

SW

= 750mA, V

SW

= 200mA, V

SW

= 750mA, V

SW

= 40kHz, ISW = 25mA, ● 58 65 72 %

OSC

= 40kHz, ISW = 25mA, ● 56 63 70 %

OSC

● 2.2 2.8 V

● 4.400 4.50 4.600 V

● 422µA

● 71114 µA/V

● 615µA/V

● 6000 12000 20000 µmho

● 5000 24000 µmho

● 450 V/V

● 50 300 mV

● 0.7 4.5 mA

● 4.2 4.4 4.6 V

● 20 75 µA

= 15V ● 13.00 13.5 V

GATE

= 15V ● 12.50 13.2 V

GATE

= 15V ● 12.75 V

GATE

= 15V ● 12.25 V

GATE

4

LT1103/LT1105

ELECTRICAL CHARACTERISTICS

VIN = 20V, VC = 0.85V, OVLO = 0V, VSW Open, TA = 25°C, unless otherwise noted.

SYMBOL PARAMETER CONDITONS MIN TYP MAX UNIT

Switch Output Low Level ISW = 200mA ● 0.25 0.50 V
(LT1105) I

Rise Time (LT1105) CL = 1000pF 50 ns
Fall Time (LT1105) CL = 1000pF 20 ns
I

Threshold Voltage (LT1105) Duty Cycle = 25% (Note 5) ● 300 375 450 mV

LIM

Low Switch Drive Lockout Measured at VSW (LT1103) ● 9.0 9.5 10.5 V
Threshold Measured at 15V Gate Bias Reference (LT1105)

High Switch Drive Lockout Measured at VSW (LT1103) ● 17.0 18.5 20.0 V
Threshold Measured at 15V Gate Bias Reference (LT1105)

= 750mA ● 0.75 1.50 V

SW

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

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

Note 2: The OVLO pin is clamped with a 5.5V Zener and can sink a
maximum input current of 1mA.

Note 3: FB input bias current changes as a function of the V
Rate of change of FB input bias current is 11µA/V of change on V

pin voltage.

C

. By

C

Note 4: Current limit on VSW is constant for DC < 35% and decreases for
DC > 35% due to internal slope compensation circuity. The LT1103 switch
current limit is given by I

Note 5: The current limit threshold voltage is constant for DC < 35% and
decreases for DC > 35% due to internal slope compensation circuitry. The
LT1105 switch current limit threshold voltage is given by V
(1.7 – DC) above 35% duty cycle.

including a resistor in series with the FB pin, load regulation can be set
to zero.

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TYPICAL PERFORMANCE CHARACTERISTICS

Start-Up Supply Current vs

Supply Current vs Input Voltage

25

20

15

10

SUPPLY CURRENT (mA)

5

I

SHUT

0

0

5

25°C

I

START

10 15 20

INPUT VOLTAGE (V)

25 30

LT1103 G01

Input Voltage

500

450

400

350
300
250
200
150
100

START-UP SUPPLY CURRENT (µA)

50

0

0

125°C

–55°C

3

6

INPUT VOLTAGE (V)

9

12

25°C

LT1103 G02

1.76 (1.536 – DC) above 35% duty cycle.

LIM =

= 0.225

LIM

Quiescent Supply Current vs
Input Voltage

22
21
20
19
18
17
16
15
14

QUIESCENT SUPPLY CURRENT (mA)

13
12

0

515

15

10

20

INPUT VOLTAGE (V)

125°C

25°C

–55°C

35

30

25

40

LT1103 G03

5

LT1103/LT1105

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TYPICAL PERFORMANCE CHARACTERISTICS

Quiescent Supply Current vs
Temperature

22
21
20
19
18
17
16
15

14

QUIESCENT SUPPLY CURRENT (mA)

13

12

–25

–50

–75

50 75 100 150

0

25

TEMPERATURE (°C)

VIN Start-Up Threshold vs
Temperature

17.5

17.0

16.5

16.0

15.5

START-UP THRESHOLD (V)

IN

V

15.0

30V

8V

125

LT1103 G04

175

Shutdown Supply Current vs
Input Voltage

500
450

A)

µ

400
350
300
250
200
150
100

SHUTDOWN SUPPLY CURRENT (

50

0

0

5

VC = 75mV

15

10

INPUT VOLTAGE (V)

VIN Shutdown Threshold vs
Temperature

8.0

7.7

7.4

7.1

SHUTDOWN THRESHOLD (V)

6.8

IN

V

VC = 0

20

Shutdown Supply Current vs
VC Voltage

500
450
400
350
300
250
200
150

SHUTDOWN CURRENT (µA)

100

50

30

LT1103 G05

35

25

0

0

–55°C

40

20

100 140 180

60

80

VC (mV)

25°C

120

125°C

160

200

LT1103 G06

Output Switch Frequency vs
Temperature

45

C

= 1000pF

OSC

43

41

39

37

OUTPUT SWITCH FREQUENCY (kHz)

14.5
–75

–50

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

Preset Switch Maximum Duty
Cycle vs Temperature

75

C

= 1000pF

OSC

72

69

66

63

PRESET SWITCH DUTY CYCLE (%)

60

–75

–25

25

0–50
TEMPERATURE (°C)

6

175

LT1103 G07

6.5
–75

–25

–50 0

75

25

50 100

TEMPERATURE (°C)

125

150

LT1103 G08

175

Switch Oscillator Frequency vs
Capacitance

1000

100

SWITCH FREQUENCY (kHz)

10

75

125

10050

150

LT1103 G10

175

100

1000 10000

CAPACITANCE (pF)

LT1103 G11

35

–50 0

–75

–25

TEMPERATURE (°C)

50 150

75

25

Overvoltage Lockout Threshold vs
Temperature

3.0

2.8

2.6

2.4

2.2

OVERVOLTAGE LOCKOUT THRESHOLD (V)

2.0
–75

–25

25

0–50
TEMPERATURE (°C)

75

10050

100

125

125

LT1103 G09

150

LT1103 G12

175

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TEMPERATURE (°C)

–75

5V LINE REGULATION (%/V)

0.03

0.04

0.05

125

LT1103 G18

0.02

0.01

0

–25

25

75

175

150

10050

0–50

TEMPERATURE (°C)

–75

15V GATE BIAS DROPOUT VOLTAGE (V)

1.5

2.0

2.5

125

LT1103 G21

1.0

0.5

0

–25

25

75

175

150

10050

0–50

TEMPERATURE (°C)

–75

SOFT-START RESET CURRENT (mA)

3

4

5

125

LT1103 G15

2

1

0

–25

25

75

175

150

10050

0–50

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TYPICAL PERFORMANCE CHARACTERISTICS

LT1103/LT1105

OVLO Input Bias Current vs
Temperature

0

OVLO = 2V

–0.5

–1.0

–1.5

–2.0

–2.5

OVLO INPUT BIAS CURRENT (µA)

–3.0

–75

–50

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

5V Reference Voltage vs
Temperature

5.20

5.15

5.10

5.05

5.00

4.95

4.90

5V REFERENCE VOLTAGE (V)

4.85

LT1103 G13

175

Soft-Start Charging Current vs
Temperature

60

50

40

30

20

10

SOFT-START CHARGING CURRENT (µA)

0

–75

–50

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

5V Load Regulation vs
Temperature

0.025

0.020

0.015

0.010

0.005

5V LOAD REGULATION (%/mA)

Soft-Start Reset Current vs
Temperature

175

LT1103 G14

5V Line Regulation vs
Temperature

4.80
–75

–50

–25

0

TEMPERATURE (°C)

5V Reference Short-Circuit
Current vs Temperature

110

100

90

80

70

60

50

40

5V REFERENCE SHORT-CIRCUIT CURRENT (mA)

30

–25

–50

0

TEMPERATURE (°C)

–75

100

50

75

25

50

75

25

100

125

125

150

LT1103 G16

150

LT1103 G19

175

175

0

–25

–75

25

0–50

TEMPERATURE (°C)

15V Gate Bias Reference vs
Temperature

16.2

15.8

15.4

15.0

14.6

15V GATE BIAS REFERENCE (V)

14.2

13.8
–75

–50

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

75

125

10050

150

LT1103 G17

175

15V Gate Bias Dropout Voltage vs
Temperature

175

LT1103 G20

7

LT1103/LT1105

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TYPICAL PERFORMANCE CHARACTERISTICS

15V Gate Bias Short-Circuit
Current vs Temperature

130

110

90

70

50

30

15V GATE BIAS SHORT-CIRCUIT CURRENT (mA)

–75

–25

25

0–50
TEMPERATURE (°C)

75

125

10050

Feedback Threshold vs
Temperature

4.60

4.56

4.52

150

LT1103 G22

175

Low Switch Drive Lockout
Threshold vs Temperature

10.5

10.2

9.9

9.6

9.3

LOW SWITCH DRIVE LOCKOUT THRESHOLD (V)

9.0

–75

–25

25

0–50
TEMPERATURE (°C)

75

10050

125

FB Input Bias Current vs
Temperature (VC = 1V)

20

16

12

150

LT1103 G23

175

High Switch Drive Lockout
Threshold vs Temperature

20.0

19.5

19.0

18.5

18.0

17.5

HIGH SWITCH DRIVE LOCKOUT THRESHOLD (V)

17.0
–75

–50

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

Change in FB Input Bias Current
with Change in VC vs Temperature
(VC = 1V to 4V)

14

13

12

(µA/V)

C

11

175

LT1103 G24

4.48

FEEDBACK THRESHOLD (V)

4.44

4.40
–75

–25

25

0–50
TEMPERATURE (°C)

75

Error Amplifier Transconductance
vs Temperature

25000

20000

15000

10000

5000

ERROR AMPLIFIER TRANSCONDUCTANCE (µmho)

–75

–50 0

–25

50

75

25

TEMPERATURE (°C)

10050

100

125

125

150

LT1103 G25

150

LT1103 G28

8

4

FB INPUT BIAS CURRENT (µA)

0

–25

175

–75

25

0–50
TEMPERATURE (°C)

Error Amplifier Transconductance
and Phase vs Frequency

0.020

0.018

0.016

0.014

0.012

0.010

0.008

0.006

0.004

0.002
0

ERROR AMPLIFIER TRANSCONDUCTANCE (mho)

175

0.1 10 100 1000

PHASE

gm

1

FREQUENCY (kHz)

75

PHASE

10

9

WITH CHANGE IN V

8

CHANGE IN FB INPUT BIAS CURRENT

7

10050

125

175

150

LT1103 G26

–75

–50

0

25

–25

TEMPERATURE (°C)

75 125

50

100

150

LT1103 G27

175

Error Amplifier Voltage Gain vs
Temperature

gm

LT1103 G29

200
180

160

140
120
100
80
60

40

20

0

2500

2000

1500

PHASE (DEGREES)

1000

ERROR AMPLIFIER VOLTAGE GAIN (V/V)

500

–75

–50

–25

0

25

TEMPERATURE (°C)

100

50

75

125

150

LT1103 G30

175

8

LPER

F

O

Error Amplifier Source Current vs
Temperature

350

325

300

275

250

225

200

175

ERROR AMPLIFIER SOURCE CURRENT (µA)

150

–50 0

–75

–25

50

75

25

TEMPERATURE (°C)

Error Amplifier Low Clamp
Voltage vs Temperature
(FB = 4.75V)

0.9

R

100

125

ATYPICA

150

LT1103 G31

175

UW

CCHARA TERIST

E

C

Error Amplifier Sink Current vs
Temperature

4.5

4.0

3.5

3.0

2.5

2.0

ERROR AMPLIFIER SINK CURRENT (mA)

1.5

1.5

–25 25 75 125

–50

–75

VC Switching Threshold Voltage
vs Temperature

ICS

0 50 100 150
TEMPERATURE (°C)

LT1103 G32

175

LT1103/LT1105

Error Amplifier High Clamp
Voltage vs Temperature
(FB = 4V)

4.5

4.4

4.3

4.2

4.1

ERROR AMPLIFIER HIGH CLAMP VOLTAGE (V)

4.0

200

–75

–25

0–50

TEMPERATURE (°C)

75

125

25

10050

LT1103 Output Switch Leakage
Current vs Temperature

150

LT1103 G33

175

0.8

0.7

0.6

0.5

0.4

ERROR AMPLIFIER LOW CLAMP VOLTAGE (V)

0.3
–75

–50

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

LT1103 Switch Saturation Voltage
vs Temperature

1.2

1.0

0.8

0.6

0.4

0.2

LT1103 SWITCH SATURATION VOLTAGE (V)

0

–75

ISW = 1.5A

ISW = 0.5A

0 50 100 150

–25 25 75 125

–50

TEMPERATURE (°C)

LT1103 G34

LT1103 G38

175

175

1.3

1.1

0.9

SWITCHING THRESHOLD (V)

C

0.7

V

0.5
–75

–25

25

0–50

TEMPERATURE (°C)

LT1103 VSW Current Limit vs
Duty Cycle

3.0

2.5

2.0

1.5

CURRENT LIMIT (A)

SW

1.0

0.5

LT1103 V

0

0

–55°C

125°C

10

25°C

30 50 70

20 40

DUTY CYCLE (%)

160

VSW = 45V

120

80

40

0

75

10050

125

175

150

LT1103 G35

LT1103 OUTPUT SWITCH LEAKAGE CURRENT (µA)

–75

–25

0–50
TEMPERATURE (°C)

VSW = 15V

75

125

25

10050

150

LT1103 G36

175

LT1103 VSW Current Limit vs
Temperature

3.0
DC = 25%

2.9

2.8

2.7

2.6

2.5

CURRENT LIMIT (A)

2.4

SW

2.3

2.2

LT1103 V

2.1

60

80

LT1103 G39

2.0

–75

–50

–25

0

25

TEMPERATURE (°C)

50 100 150

75

125

LT1103 G40

175

9

LT1103/LT1105

TEMPERATURE (°C)

–75

LT1105 V

SW

FALL TIME (ns)

60

80

100

125

LT1103 G45

40

20

0

–25

25

75

175

150

10050

0–50

C

LOAD

= 4700pF

C

LOAD

= 1000pF

LPER

F

O

R

ATYPICA

UW

CCHARA TERIST

E

C

ICS

LT1103 Driver Current vs
Temperature

50

40

30

20

10

LT1103 DRIVER CURRENT (mA/A)

0

–75

–25

0–50
TEMPERATURE (°C)

75

25

LT1105 Current Limit Threshold
Voltage vs Temperature

450

DC = 25°C

425

400

375

350

325

LT1105 VSW Low Saturation
Voltage vs Temperature

3.0

2.5

2.0

1.5

1.0

LOW SATURATION VOLTAGE (V)

SW

0.5

LT1105 V

0

–75

10050

125

175

150

LT1103 G41

–50

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

ISW = 750mA

ISW = 200mA

175

LT1103 G42

LT1105 VSW Rise Time vs
Temperature

100

80

C

= 4700pF

C

LOAD

LOAD

= 1000pF

60

RISE TIME (ns)

SW

40

LT1105 V

20

LT1105 VSW High Saturation
Voltage vs Temperature

3.0

2.5

2.0

1.5

1.0

HIGH SATURATION VOLTAGE (V)

SW

0.5

LT1105 V

0
–75

–50

ISW = 750mA

ISW = 200mA

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

LT1105 VSW Fall Time vs
Temperature

175

LT1103 G43

300

LT1105 CURRENT LIMIT THRESHOLD VOLTAGE (mV)

–75

–50

10

0 50 100 150

–25 25 75 125

TEMPERATURE (°C)

LT1103 G46

175

0

–75

–25

25

0–50

TEMPERATURE (°C)

75

10050

125

175

150

LT1103 G44