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LT1612

SYMBOL PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

SHDN Pin Current

SHDN = 2V

µA

SHDN = 5V

µA

BOOST Pin Current

BOOST = VIN + 2V

Switch Current Limit (Note 4)

Duty Cycle = 0%

MODE = OV

600

710

900

MODE = 5V

550

650

900

Burst Mode Operation Current Limit

MODE = 0V

180

Switch Voltage Drop

ISW = 500mA

200

280

Rectifier Voltage Drop

IRECT = 500mA

300

400

SW Pin Leakage

VSW = 5V

µA

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

of a device may be impaired.

Note 2: The LT1612E is guaranteed to meet performance specifications

from 0

°C to 70°C. Specifications over the –40°C to 85°C operating

ELECTRICAL CHARACTERISTICS

VC (Pin 1): Compensation Pin. This is the current sink/

source output of the error amplifier. By connecting an RC

network from this pin to ground, frequency response can

be tuned for a wide range of circuit configurations. The

voltage at this pin also sets the current limit, and if

grounded, the switch will remain in the OFF state.

FB (Pin 2): Feedback Pin. This pin is the negative input to

the error amplifier. Connect the resistor divider tap to this

point which sets VOUT according to:

VOUT = 0.62V (1 + R1/R2)

VIN (Pin 3): Supply Pin. Bypass capacitor C1 must be right

next to this pin.

GND (Pin 4): Ground Pin. Connect directly to local ground

plane.

PIN FUNCTIONS

SW (Pin 5): Switch Pin. Connect inductor and boost

capacitor here. Minimize trace area at this pin to keep EMI

down.

BOOST (Pin 6): This is the supply pin for the switch driver

and must be above VIN by 1.5V for proper switch opera-

tion. Connect the boost capacitor to this pin.

MODE (Pin 7): Burst Mode Operation Disable Pin. For

continuous switching operation (low noise), pull this pin

above 2V. For Burst Mode operation which gives better

light load efficiency, tie to ground. Output ripple voltage in

Burst Mode operation is typically 30mVP-P. See applica-

tions section for more information about this function.

SHDN (Pin 8): Shutdown Pin. Pull this pin low for shut-

down mode. Tie to a voltage between 2V and 5.5V for

normal operation.

The q denotes specifications which apply over the full operating

temperature range, otherwise specifications are TA = 25°C, VIN = VSHDN = 3V

temperature range are assured by design, characterization and correlation

with statistical process controls.

Note 3: Bias current flows out of the FB pin.

Note 4: Duty cycle affects current limit due to slope compensation.

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