© 2000 SEMTECH CORP.

652 MITCHELL ROAD NEWBURY PARK CA 91320

LOW VOLTAGE, BOOST DC-DC

CONTROLLER

SC1408

August 22, 2000

9

Vo=3.3V

100mOhm

50mOhm

35mOhm

25mOhm

20mOhm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

2.0

2.2

2.4

2.6

2.8

3.0

3.2

Vin (V)

L=22uH

Vo=5V

100mOhm

50mOhm

35mOhm

25mOhm

20mOhm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

Vin (V)

L=22uH

Vo=12V

100mOhm

50mOhm

35mOhm

25mOhm

20mOhm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

2.0

4.0

6.0

8.0

10.0

12.0

Vin (V)

L=22uH

Vo=15V

100mOhm

50mOhm

35mOhm

25mOhm

20mOhm

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

Vin (V)

L=22uH

Figs. 5 - 8: Maximum output current vs. input voltage and sense resistor value. (Boost Mode)

Vo=15V

60%

70%

80%

90%

100%

1

10

100

1000

Io (mA)

Vin=12V

Vin=9.0V

Vin=5.0V

Vin=3.0V

Vin=1.8V

Vo=12V

60%

70%

80%

90%

100%

1

10

100

1000

Io (mA)

Vin=5.0V

Vin=3.0V

Vin=1.8V

Vo=5V

60%

70%

80%

90%

100%

1

10

100

1000

Io (mA)

Vin=5.0V

Vin=4.0V

Vin=3.3V

Vin=3.0V

Figs. 9-11:Efficiency in the Boost Application circuit of Fig.1