LTC3458 datasheet(8/16 Pages) LINER

8 / 16 page

LTC3458

3458f

Detailed Description

The LTC3458 provides high efficiency, low noise power

for boost applications with output voltages up to 7.5V. The

true output disconnect feature eliminates inrush current,

and allows VOUT to go to zero during shutdown. The

current mode architecture with adaptive slope compensa-

tion provides ease of loop compensation with excellent

transient load response. The low RDS(ON), low gate charge

synchronous switches eliminate the need for an external

Schottky rectifier, and provide efficient high frequency

pulse width modulation (PWM) control. High efficiency is

achieved at light loads when Burst Mode operation is

entered, where the IC’s quiescent current is a low 15µA

typical on VIN. The LTC3458 is designed to provide custom

performance in a variety of applications with program-

mable feedback, current limit, oscillator frequency, soft-

start, and Burst Mode threshold.

BLOCK DIAGRA

PGND

VBEST

VSELECT

OSC/SYNC

MAX

DUTY

SYNC

GND

ILIM

PGND

COMP

SHDN

VCC

VOUT

BURST

PWM

AND

BURST MODE

DRIVE LOGIC

P-DRIVE

N-DRIVE

IZERO

DETECT

BURST MODE

CONTROL

FIXED

FREQUENCY

BURST MODE

MUX

SOFT-START

THERMAL SD

UNDERVOLTAGE

REFERENCE/

BIAS

PEAK CURRENT

COMPARATOR

ICOMP, ILIMIT,

IBURST_PEAK,

SLOPE COMP

SLEEP

CONTROL

MODE

ICOMP/LIMIT_PEAK

IBURST_PEAK

SLOPE

SLEEP TO

ALL BLOCKS

I_SENSE

BURST ACTIVE

(DISABLED IN

BURST MODE)

–

TSD

ANTIRING

SW1

UNDER

TO ALL BLOCKS

SDB

BIAS

CURRENTS

UVLO

IZERO

3458 BD

ERROR AMPLIFIER/

BURST COMPARATOR

APPLICATIO S I FOR ATIO

LTC3458 Programmable Functions

Current Limit/Peak Burst Current. The programmable

current limit circuit sets the maximum peak current in the

internal N-channel MOSFET switch. This clamp level is

programmed using a resistor to ground on ILIM. In Burst

Mode operation, the current limit is automatically set to

~1/4 of the programmed current limit for optimal effi-

ciency. A 124k RILIM resistor is recommended in most

applications unless a lower limit is needed to prevent the

external inductor from saturating.

LIM =

200

I is in amps and R is in kΩ.

BURSTPEAK

LIM

≈

•

LTC3458 Datasheet(PDF) 8 Page - Linear Technology

LTC3458 Datasheet(HTML) 8 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Datasheet Download

Link URL