3

LTC1649

Note 1: Absolute Maximum Ratings are those values beyond which the life

of a part may be impaired.

Note 2: All currents into device pins are positive; all currents out of device

pins are negative. All voltages are referenced to ground unless otherwise

specified.

Note 3: Maximum Duty Cycle limitations will limit the output voltage

obtainable at very low supply voltages.

needed to charge and discharge the external MOSFET gates. This current

will vary with the operating voltage and the external MOSFETs used.

Note 5: Under normal operating conditions, the charge pump will skip

cycles to maintain regulation and the apparent frequency will be lower than

700kHz.

Note 7: Driver rise and fall times are measured from 10% to 90%.

TYPICAL PERFOR A CE CHARACTERISTICS

TEMPERATURE (

°C)

–40

210

220

240

20

60

1649 G02

200

190

–20

0

40

80

100

180

170

230

Oscillator Frequency

vs Temperature

TEMPERATURE (

°C)

–40

12.5

13.0

14.0

20

60

1649 G01

12.0

11.5

–20

0

40

80

100

11.0

10.5

13.5

TEMPERATURE (

°C)

–40

70

75

85

90

95

0

40

60

1649 G03

80

–20

20

80

100

100

Maximum Duty Cycle

vs Temperature

Error Amplifier Transconductance

vs Temperature

TEMPERATURE (

°C)

–40

350

400

500

550

600

850

700

0

40

60

100

1649 G04

450

750

800

650

–20

20

80

Output Voltage vs Load Current

with Current Limit

LOAD CURRENT (A)

0

1.5

2.0

2.5

6

10

1649 G07

1.0

0.5

0

24

8

3.0

3.5

4.0

12

FIGURE 1

Load Regulation

LOAD CURRENT (A)

0

–1.0

– 0.8

– 0.4

– 0.2

0

0.4

1

5

7

1649 G06

– 0.6

0.2

4

9

10

2

3

68

FIGURE 1

ELECTRICAL CHARACTERISTICS