LT3070 datasheet(19/24 Pages) LINER

19 / 24 page

LT3070

3070p

APPLICATIONS INFORMATION

Quieting the Noise

The LT3070 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 LT3070 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 CBYP/REF.

This approach also accommodates reference sharing

between LT3070 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).

BIAS

50k

LT3070

VO0

VO1

330μF

2.2μF

2.2μF*

0.01μF

1nF

4.7μF*

3070 F06

10μF*

*X5R OR X7R

PWRGD

VOUT

1.2V

VO2

MARGSEL

MARGTOL

VIOC

SENSE

OUT

VBIAS

3.3V

VIN

1.5V

PWRGD

REF/BYP

GND

Figure 6. 1.5V to 1.2V Linear Regulator

LT3070 Datasheet(PDF) 19 Page - Linear Technology

LT3070 Datasheet(HTML) 19 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24

Datasheet Download

Link URL