LT3991EDDPBF LINER [Linear Technology], LT3991EDDPBF Datasheet

LT3991EDDPBF

Manufacturer Part Number

LT3991EDDPBF

Description

55V, 1.2A Step-Down Regulator with 2.8 Quiescent Current

Manufacturer

LINER [Linear Technology]

Datasheet

1.LT3991EDDPBF.pdf (24 pages)

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APPLICATIONS

TYPICAL APPLICATION

FEATURES

4.3V TO 55V

Ultralow Quiescent Current:

2.8μA I

Low Ripple Burst Mode

Output Ripple < 15mV

Wide Input Voltage Range: 4.3V to 55V

1.2A Maximum Output Current

Adjustable Switching Frequency: 200kHz to 2MHz

Synchronizable Between 250kHz to 2MHz

Fast Transient Response

Accurate 1V Enable Pin Threshold

Low Shutdown Current: I

Power Good Flag

Soft-Start Capability

Internal Compensation

Saturating Switch Design: 0.44Ω On-Resistance

Output Voltage: 1.19V to 30V

Small Thermally Enhanced 10-Pin MSOP Package

and (3mm × 3mm) DFN Packages

Automotive Battery Regulation

Power for Portable Products

Industrial Supplies

Regulating 12V

4.7μF

OFF ON

118k

3.3V Step Down Converter

P-P

SYNC

Operation:

LT3991

= 700nA

to 3.3V

GND

BOOST

OUT

0.47μF

1.78M

10μH

10pF

3991 TA01

47μF

3.3V

1.2A

DESCRIPTION

The LT

switching regulator that accepts a wide input voltage range

up to 55V. Low quiescent current design consumes only

2.8μA of supply current while regulating with no load. Low

ripple Burst Mode operation maintains high efﬁ ciency at

low output currents while keeping the output ripple below

15mV in a typical application. An internally compensated

current mode topology is used for fast transient response

and good loop stability. A high efﬁ ciency 0.44Ω switch

is included on the die along with a boost Schottky diode

and the necessary oscillator, control and logic circuitry.

An accurate 1V threshold enable pin can be used to shut

down the LT3991, reducing the input supply current to

700nA. A capacitor on the SS pin provides a controlled

inrush current (soft-start). A power good ﬂ ag signals

when V

age. The LT3991 is available in small 10-pin MSOP and

3mm × 3mm DFN packages with exposed pads for low

thermal resistance.

L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective

owners.

OUT

3991 is an adjustable frequency monolithic buck

reaches 91% of the programmed output volt-

55V, 1.2A Step-Down

Regulator with 2.8µA

Quiescent Current

4.0

3.5

3.0

2.5

2.0

1.5

1.0

No Load Supply Current

INPUT VOLTAGE (V)

LT3991

3991 TA01b

3991f

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