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LTC1771

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

of a device may be impaired.

Note 2: TJ is calculated from the ambient temperature TA and power

dissipation PD according to the following formulas:

LTC1771S8: TJ = TA + (PD)(110°C/W)

LTC1771MS8: TJ = TA + (PD)(150°C/W)

Note 3: The LTC1771E is guaranteed to meet performance specifications

from 0

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

temperature range are assured by design, characterization and correlation

with statistical process controls. The LTC1771I is guaranteed and tested

over the – 40

°C to 85°C operating temperature range.

The q denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.

VIN = 10V, VRUN = open unless otherwise specified.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

VRUN/SS

RUN/SS Pin Threshold

VRUN/SS Rising

0.5

1.0

IRUN

Source Current

VRUN = 0V, VIN = 2.8V to 18V

0.3

µA

PGATE tr, tf

PGATE Transition Time (Note 7)

Rise Time

CLOAD = 2000pF

Fall Time

CLOAD = 2000pF

Note 4: Dynamic supply current is higher due to the gate charge being

delivered at the switching frequency. See Applications Information.

Note 5: The LTC1771 is tested in a feedback loop that servos VFB to the

balance point for the error amplifier (VITH = 1.23V).

Note 6: No-load supply current consists of sleep mode current (9

µA

typical) plus a small switching component necessary to overcome

Schottky diode leakage and feedback resistor current.

Note 7: tr and tf measured at 10% to 90% levels.

RUN/SS (Pin 1): The voltage level on this pin controls

shutdown/run mode (ground = shutdown, open/high =

run). Connecting an external capacitor to this pin provides

soft-start.

ITH (Pin 2): Error Amplifier Compensation Point. The

current comparator threshold increases with this control

voltage. Nominal voltage range for this pin is 0V to 3V.

VFB (Pin 3): Feedback of Output Voltage for Comparison

to Internal 1.23V Reference. An external resistive divider

across the output is returned to this pin.

GND (Pin 4): Ground Pin.

PGATE (Pin 5): High Current Gate Driver for External

P-Channel MOSFET Switch. Voltage swing is from ground

to VIN.

VIN (Pin 6): Main Input Voltage Supply Pin.

SENSE (Pin 7): Current Sense Input for Monitoring Switch

Current. Maximum switch current and Burst Mode

threshold is programmed with an external resistor be-

tween SENSE and VIN.

MODE (Pin 8): Burst Mode Enable/Disable Pin. Connect-

ing this pin to VIN (or above 2V) enables Burst Mode

operation, while connecting this pin to ground disables

Burst Mode operation. Do not leave floating.

ELECTRICAL CHARACTERISTICS

PI FU CTIO S

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