LTC1626CS datasheet(4/12 Pages) LINER

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LTC1626

PWR VIN (Pins 1, 13): Supply for the Power MOSFET and

Its Driver. Decouple this pin properly to ground.

VIN (Pin 2): Main Supply for All the Control Circuitry in

the LTC1626.

LBO (Pin 3): Open-Drain Output of the Low-Battery Com-

parator. This pin will sink current when Pin 4 (LBI) goes

below 1.25V. During shutdown, this pin is high imped-

ance.

LBI (Pin 4): The (–) Input of the Low-Battery Comparator.

The (+) input is connected to a reference voltage of 1.25V.

If not used, connect to VIN.

CT (Pin 5): External capacitor CT from Pin 5 to ground sets

the switch off-time. The operating frequency is dependent

on the input voltage and CT.

ITH (Pin 6): Feedback Amplifier Decoupling Point. The

current comparator threshold is proportional to Pin 6

voltage.

PIN FUNCTIONS

SENSE – (Pin 7): Connects to the (–) Input of the Current

Comparator.

SENSE + (Pin 8): The (+) Input to the Current Comparator.

A built-in offset between Pins 7 and 8 in conjunction with

RSENSE sets the current trip threshold.

VFB (Pin 9): This pin serves as the feedback pin from an

external resistive divider used to set the output voltage.

SHDN (Pin 10): Shutdown Pin. Pulling this pin to VIN

keeps the internal switch off and puts the LTC1626 in

micropower shutdown. If not used, connect to SGND.

SGND (Pin 11): Small-Signal Ground. Must be routed

separately from other grounds to the (–) terminal of COUT.

PWR GND (Pin 12): Switch Driver Ground. Connects to

the (–) terminal of CIN.

SW (Pin 14): Drain of the P-Channel MOSFET Switch.

Cathode of the Schottky diode must be connected closely

to this pin.

BLOCK DIAGRAM

–

PWR GND

–

SLEEP

VTH2

VFB

VTH1

VIN

SENSE–

SENSE+

25mV TO 150mV

OFF-TIME

CONTROL

ITH

LBO

LBI

1626 BD

VOS

SHDN

SGND

13k

PWR VIN

REFERENCE

LTC1626CS Datasheet(PDF) 4 Page - Linear Technology

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