LTC3521



3521f

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: The LTC3521 is guaranteed to meet performance specifications

from 0°C to 85°C. Specifications over the –40°C to 85°C operating

junction temperature range are assured by design, characterization and

correlation with statistical process controls.

Note 3: Current measurements are performed when the LTC3521 is not

switching. The current limit values in operation will be somewhat higher

due to the propagation delay of the comparators.

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Oscillator Frequency

l

0.85

1.1

1.35

MHz

SHDN1, SHDN2, SHDN3, PWM Input High Voltage

l

1.4

V

SHDN1, SHDN2, SHDN3, PWM Input Low Voltage

l

0.4

V

Power Good Outputs Low Voltage

0.1

0.2

V

Power Good Outputs Leakage Current

0.1

10

µA

Buck Converters

PMOS Switch Resistance

0.205

Ω

NMOS Switch Resistance

0.170

Ω

NMOS Switch Leakage Current

0.1

5

µA

PMOS Switch Leakage Current

0.1

10

µA

Feedback Voltage

(Note 4)

l

0.585

0.6

0.612

V

Feedback Input Current

1

50

nA

PMOS Current Limit

(Note 3)

l

750

1050

mA

Maximum Duty Cycle

l

100

%

Minimum Duty Cycle

l

0

%

PGOOD Threshold

–12

–9

–6

%

Power Good Hysteresis

2

%

Buck-Boost Converter

Output Voltage

l

1.8

5.25

V

PMOS Switch Resistance

0.110

Ω

NMOS Switch Resistance

0.085

Ω

NMOS Switch Leakage Current

0.1

5

µA

PMOS Switch Leakage Current

0.1

10

µA

Feedback Voltage

(Note 4)

l

0.585

0.6

0.612

V

Feedback Input Current

1

50

nA

Average Current Limit

(Note 3)

l

1.65

2.1

A

Reverse Current Limit

(Note 3)

375

mA

Maximum Duty Cycle

l

85

94

%

Minimum Duty Cycle

l

0

%

PGOOD Threshold

–12

–9

–6

%

Power Good Hysteresis

3

%

l

denotes the specifications which apply over the full operating

Note 4: The LTC3521 is tested in a proprietary test mode that connects

each FB pin to the output of the respective error amplifier.

Note 5: This IC includes overtemperature protection that is intended

to protect the device during momentary overload conditions. Junction

temperature will exceed 125°C when overtemperature protection is active.

Continuous operation above the specified maximum operating junction

temperature may impair device reliability.