LTC1265CS datasheet(4/16 Pages) LINER

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LTC1265/LTC1265-3.3/LTC1265-5

TYPICAL PERFORMANCE CHARACTERISTICS

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

its Driver. Must decouple this pin properly to ground. Must

always tie Pins 1 and 13 together.

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

LTC1265.

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

Comparator. This pin will sink current when Pin 4 (LBIN)

goes below 1.25V. During shutdown, this pin is high

impedance.

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

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

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.

SENSE – (Pin 7): Connect to the (–) input of the current

comparator. For LTC1265-3.3 and LTC1265-5, it also

connects to an internal resistive divider which sets the

output voltage.

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

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

RSENSE sets the current trip threshold.

N/C,VFB (Pin 9): For the LTC1265 adjustable version, this

pin serves as the feedback pin from an external resistive

divider used to set the output voltage. On the LTC1265-3.3

and LTC1265-5 versions, this pin is not used.

SHDN (Pin 10): Pulling this pin HIGH keeps the internal

switch off and puts the LTC1265 in micropower shut-

down. Do not float this pin.

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

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

PGND (Pin 12): Switch Driver Ground. Connects to the

(–) terminal of CIN. Anode of the Schottky diode must be

connected close to this pin.

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

Cathode of the Schottky diode must be connected close to

this pin.

PIN FUNCTIONS

DC Supply Current

Supply Current in Shutdown

Gate Charge Losses

INPUT VOLTAGE (V)

0.3

0.6

0.9

2.1

1.5

814

1.8

1.2

DOES NOT INCLUDE

GATE CHARGE

ACTIVE MODE

SLEEP MODE

1265 G07

INPUT VOLTAGE (V)

1265 G08

SHUTDOWN = 3V

TA = 25C

FREQUENCY (kHz)

1.0

2.0

3.0

4.0

200

400

1265 G09

600

5.0

5.5

4.5

3.5

2.5

1.5

0.5

800

1000

VIN = 12V

VIN = 9V

VIN = 6V

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