LTC1649 Ver la hoja de datos (PDF) - Linear Technology

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LTC1649

3.3V Input High Power Step-Down Switching Regulator Controller

Linear Technology 

LTC1649

ELECTRICAL CHARACTERISTICS

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.

Note 4: Supply current at PVCC1 and PVCC2 is dominated by the current

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 6: The ILIM amplifier can sink but not source current. Under normal

(not current limited) operation, the ILIM output current will be zero.

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

TYPICAL PERFOR A CE CHARACTERISTICS

IMAX Pin Current vs Temperature

14.0

VCC = 5V

13.5

Oscillator Frequency

vs Temperature

240

VCC = 5V

230

13.0

220

12.5

210

12.0

200

11.5

190

11.0

180

10.5

– 40 –20

0 20 40 60

TEMPERATURE (°C)

80 100

1649 G01

170

– 40 –20

0 20 40 60

TEMPERATURE (°C)

80 100

1649 G02

Error Amplifier Transconductance

vs Temperature

850

800

gm

=

∆ICOMP

∆VFB

750

VCC = 5V

700

650

600

550

500

450

400

350

– 40 – 20

0 20 40 60

TEMPERATURE (°C)

80 100

1649 G04

Load Regulation

0.4

TA = 25°C

0.2 VOUT = 3.3V

VCC = 5V

FIGURE 1

0

– 0.2

– 0.4

– 0.6

– 0.8

– 1.0

0 1 2 3 4 5 6 7 8 9 10

LOAD CURRENT (A)

1649 G06

Maximum Duty Cycle

vs Temperature

100

VCOMP = VCC

95

VFB = 1.265V

VCC = 5V

90

85

80

75

70

– 40 – 20

0 20 40 60

TEMPERATURE (°C)

80 100

1649 G03

Output Voltage vs Load Current

with Current Limit

4.0

3.5

3.0

2.5

2.0

RIMAX = 16k

RIMAX = 33k

1.5

1.0

TA = 25°C

0.5 VCC = 5V

FIGURE 1

0

0

2

4

6

8

LOAD CURRENT (A)

10 12

1649 G07

3

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