LTC1474 View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LTC1474

Low Quiescent Current High Efficiency Step-Down Converters

Linear Technology 

LTC1474/LTC1475

PIN FUNCTIONS

VOUT/VFB (Pin 1): Feedback of Output Voltage. In the fixed

versions, an internal resistive divider divides the output

voltage down for comparison to the internal 1.23V refer-

ence. In the adjustable versions, this divider must be

implemented externally.

LBO (Pin 2): Open Drain Output of the Low Battery

Comparator. This pin will sink current when Pin 3 is below

1.23V.

LBI/OFF (Pin 3): Input to Low Battery Comparator. This

input is compared to the internal 1.23V reference. For the

LTC1475, a momentary ground on this pin puts regulator

in shutdown mode.

GND (Pin 4): Ground Pin.

SW (Pin 5): Drain of Internal PMOS Power Switch. Cath-

ode of Schottky diode must be closely connected to this

pin.

SENSE (Pin 6): Current Sense Input for Monitoring Switch

Current and Source of Internal PMOS Power Switch.

Maximum switch current is programmed with a resistor

between SENSE and VIN pins.

VIN (Pin 7): Main Supply Pin.

RUN/ON (Pin 8): On LTC1474, voltage level on this pin

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

high = run). On LTC1475, a momentary ground on this pin

puts regulator in run mode. A 100k series resistor must be

used between Pin 8 and the switch or control voltage.

W

FUNCTIONAL DIAGRA

LBI/OFF

1µA

100mV

×

C

ON

LTC1474: RUN 8

LTC1475: ON

LBO 2

1-SHOT

4.75µs

TRIGGER

OUT

STRETCH WAKEUP

V

ON

LB

1.23V

READY

3 LTC1474: LBI

LTC1475: LBI/OFF

× CONNECTION NOT PRESENT IN LTC1474 SERIES

CONNECTION PRESENT IN LTC1474 SERIES ONLY

1.23V

REFERENCE

VIN

7

RSENSE

(OPTIONAL)

VIN

+

VCC

6

SENSE

5Ω

1×

20×

SW

5

3M

(5V VERSION)

1.68M

(3.3V VERSION)

VOUT/VFB

1

VOUT

+

4 GND

1M

OUTPUT DIVIDER IS

IMPLEMENTED EXTERNALLY IN

ADJUSTABLE VERSIONS

1474/75 FD

5

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