LT3071MPUFD View Datasheet(PDF) - Linear Technology

Part Name

Description

Manufacturer

LT3071MPUFD

5A, Low Noise, Programmable Output, 85mV Dropout Linear Regulator with Analog Margining

Linear Technology 

LT3071

APPLICATIONS INFORMATION

Quieting the Noise

The LT3071 offers numerous noise performance advan-

tages. Each LDO has several sources of noise. An LDO’s

most critical noise source is the reference, followed by

the LDO error amplifier. Traditional low noise regulators

buffer the voltage reference out to an external pin (usually

through a large value resistor) to allow for bypassing and

noise reduction of reference noise. The LT3071 deviates

from the traditional voltage reference by generating a

low voltage VREF from a reference current into an inter-

nal resistor ≅ 19k. This intermediate impedance node

(REF/BYP) facilitates external filtering directly. A 10nF filter

capacitor minimizes reference noise to 10µVRMS at the

600mV REF/BYP pin, equivalently a 17µV contribution to

output noise at VOUT = 1V. See the Typical Performance

Characteristics for Noise vs Output Voltage performance

as a function of CREF/BYP .

This approach also accommodates reference sharing

between LT3071 regulators that are hooked up in cur-

rent sharing applications. The REF/BYP filter capacitor

delays the initial power-up time by a factor of the RC time

constant. VREF remains active in nap mode, thus start-up

time is significantly reduced and well controlled coming

out of nap mode (EN:LO↑HI).

VBIAS

2.2V TO 3.6V

50k

2.2µF

VIN

1.5V

BIAS

IN

PWRGD

330µF

EN

SENSE

VO0 LT3071 OUT

VO1

VO2

NC

1nF

MARGA

IMON

VIOC

REF/BYP

GND

PWRGD

2.2µF*

4.7µF*

VOUT

1.2V

5A

10µF*

*X5R OR X7R CAPACITORS

0.01µF 1k

3071 F06

VMON

2V AT 5A

FULL SCALE

Figure 6. 1.5V to 1.2V Linear Regulator

3071fc

24

For more information www.linear.com/LT3071

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