5

LT1107

lower current limit is desired, connect a resistor between

to approximately 400mA.

SW1 (Pin 3): Collector of Power Transistor. For step-up

mode connect to inductor/diode. For step-down mode

SW2 (Pin 4): Emitter of Power Transistor. For step-up

mode connect to ground. For step-down mode connect to

inductor/diode. This pin must never be allowed to go more

than a Schottky diode drop below ground.

GND (Pin 5): Ground.

AO (Pin 6): Auxiliary Gain Block (GB) Output. Open collector,

can sink 300

µA.

SET (Pin 7): GB Input. GB is an op amp with positive input

connected to SET pin and negative input connected to

1.25V reference.

FB/SENSE (Pin 8): On the LT1107 (adjustable), this pin

goes to the comparator input. On the LT1107-5 and

LT1107-12, this pin goes to the internal application resistor

that sets output voltage.

PI

FU C

S

TI

CC

HARA TERISTICS

A

TYPICALPERFOR

CE

Minimum/Maximum Frequency

Minimum/Maximum Frequency

Duty Cycle

vs ON Time, Step-Down Mode

vs ON Time, Step-Up Mode

Step-Down Mode

TEMPERATURE (°C)

–55

–15

25

45

125

1107 G13

–35

5

65

85 105

70

65

60

55

50

45

40

35

TEMPERATURE (°C)

–55

–15

25

45

125

1107 G16

–35

5

65

85 105

5.3

5.2

5.1

5.0

4.9

4.8

4.7

TEMPERATURE (°C)

–55

–15

25

45

125

1107 G17

–35

5

65

85 105

12.20

12.15

12.10

12.05

12.00

11.95

11.90

11.85

11.80

LT1107-5

LT1107-12

LT1107

Output Voltage

Output Voltage

Feedback Voltage

TEMPERATURE (°C)

–55

–15

25

45

125

1107 G18

–35

5

65

85 105

1.30

1.29

1.28

1.27

1.26

1.25

1.24

1.23

1.22

1.21

1.20

ON TIME (

µs)

4

100

90

80

70

60

50

40

30

5

9

11

1107 G11

8

13 14

6

7

10

12

–55

0

ON TIME (

µs)

6

100

90

80

70

60

50

40

30

7

11

13

1107 G12

10

15 16

8

9

12

14

–55

0