MIC2808

RF PA Power Management IC

2MHz, 600mA DC/DC w/DAC Input and

Bypass Switch, Dual Low Noise

200mA/30mA LDO Regulators

MLF and MicroLeadFrame are registered trademarks of Amkor Technology, Inc.

Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com

General Description

The MIC2808 integrates a high performance 600mA

DC/DC step down regulator intended for powering a power

amplifier (PA) in a mobile phone with dual low noise low

dropout (LDO) regulators for the rest of the RF section.

Optimized for low noise performance, the MIC2808

improves efficiency in the handset without compromising

quality.

The MIC2808 has a 2MHz, constant frequency pulse width

modulated (PWM) DC/DC regulator designed for low noise

The regulator will work in a 100% duty cycle mode to offer

maximum power and efficiency in the application. In

addition to 100% duty cycle, the DC/DC regulator has a

bypass mode of operation where the input voltage node

(PVIN pin) is shorted to the output voltage node (OUT pin)

through a 95mΩ switch.

The integrated dual low noise low dropout regulators are

optimized for high PSRR capability and fast turn-on times.

The constant frequency DC/DC regulator along with dual

low noise LDO regulators enables a very quiet and

efficient solution for mobile applications.

The MIC2808 is a µCap design, operating with small

ceramic output capacitors and inductors for stability,

reducing required board space and component cost and it

is available in the tiny 2.0mm x 2.5mm TMLF

Data sheets and support documentation can be found on

Micrel’s web site at: www.micrel.com.

Features

• 2.7V to 5.5V input voltage range

• Stable with ceramic output capacitors

• Thermal shutdown protection

• Current limit protection

RF PA Power Supply DC/DC Regulator

• Adjustable output power supply – DAC controlled

–

• Bypass mode operation

–

Internal 95mΩ switch between PVIN and OUT pins

–

• Up to 600mA output current in PWM mode

• 100% duty cycle operation for maximum efficiency

• Tiny 4.7µH, 1µF output inductor and capacitor

• Low-noise 2MHz PWM operation

• >90% efficiency

Dual Low Noise Low Dropout Regulators

• High accuracy – ±2% over temperature

• High PSRR – greater than 70dB

• Very low output noise – 32µVrms

• LDO1 – 200mA output current capability

• LDO2 – 30mA output current capability

Applications

• CDMA2000 mobile phones

• UMTS/WCDMA mobile phones

• WiMAX/Wibro modules

• WiFi modules

• Power amplifier modules (PAMs) with linear PAs

Typical Application

CDMA2000/WCDMA RF Power Supply Circuit

0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0.1 0.3 0.5 0.7 0.9 1.1 1.3 1.5

DAC VOLTAGE (V)

DC/DC Output Voltage

vs. DAC Voltage

July 2009

M9999-071709-A