August, 2004

1

M0385-080204

MIC5255

Micrel

MIC5255

150mA Low Noise

General Description

The MIC5255 is an efficient, precise CMOS voltage regulator

optimized for ultra-low-noise applications. It offers 1% initial

accuracy, extremely-low dropout voltage (135mV at 150mA)

and low ground current (typically 90

µA). The MIC5255 pro-

vides a very-low-noise output, ideal for RF applications

where a clean voltage source is required. A noise bypass pin

is also available for further reduction of output noise.

Designed specifically for handheld and battery-powered de-

vices, the MIC5255 provides a TTL-logic-compatible enable

pin. When disabled, power consumption drops nearly to zero.

The MIC5255 also works with low-ESR ceramic capacitors,

reducing the amount of board space necessary for power

applications, critical in handheld wireless devices.

Key features include current limit, thermal shutdown, faster

transient response, and an active clamp to speed up device

turn-off. Available in the 6-pin 2mm

× 2mm MLF™ package,

the IttyBitty® SOT-23-5 package and the new Thin SOT-23-

5, which offers the same footprint as the standard IttyBitty®

SOT-23-5, but only 1mm tall. The MIC5255 offers a range of

output voltages.

All support documentation can be found on Micrel’s web

site at www.micrel.com.

Features

• Input voltage range: 2.7V to 6.0V

• Thin SOT package: 1mm height SOT-23-5

• Ultra-low output noise: 30

µV(rms)

• Stability with ceramic output capacitors

• Ultra-low dropout: 135mV @ 150mA

• High output accuracy:

1.0% initial accuracy

2.0% over temperature

• Low quiescent current: 90

µA

• Tight load and line regulation

• TTL-Logic-controlled enable input

• “Zero” off-mode current

• Thermal shutdown and current limit protection

Applications

• Cellular phones and pagers

• Cellular accessories

• Battery-powered equipment

• Laptop, notebook, and palmtop computers

• Consumer/personal electronics

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000• http://www.micrel.com

IttyBitty is a registered trademark of Micrel, Inc.

Typical Application

Ceramic

Ceramic

15

2

3

4

Enable

Shutdown

EN

MIC5255-x.xBM5

EN (pin 3) may be

connected directly

to IN (pin 1).

MIC5255-x.xBML

1

EN

6

(optional)

5

4

2

3

ENABLE

SHUTDOWN

Ultra-Low-Noise Regulator Application