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600mA/650mA PWM Step-Down Converters in 2mm x 2mm WLP for WCDMA PA Power

Small (4mm)² Package Provides Power and Bias to 2 WCDMA PA Modules

Product Details

Key Features

Simplified Block Diagram

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Key Features

  • PA Step-Down Converter
    • 7.5µs (typ) Settling Time for 0.8V to 3.4V Output Voltage Change
    • Dynamic Output Voltage Setting from 0.4V to VBATT
    • 60mΩ pFET and 100% Duty Cycle for Low Dropout
    • 2MHz or 4MHz Switching Frequency
    • Low Output-Voltage Ripple
    • 600mA (MAX8805Y/MAX8805Z) or 650mA (MAX8805W/MAX8805X) Output Drive Capability
    • 2% Gain Accuracy
    • Tiny External Components
  • Dual Low-Noise LDOs
    • Low 35µVRMS (typ) Output Noise
    • High 70dB (typ) PSRR
    • Guaranteed 200mA Output Drive Capability
    • Individual ON/OFF Control
  • Low 0.1µA Shutdown Current
  • 2.7V to 5.5V Supply Voltage Range
  • Thermal Shutdown
  • Tiny 2mm x 2mm x 0.7mm WLP and UCSP Packages (4 x 4 Grid)

Applications/Uses

  • Smartphones
  • WCDMA/NCDMA Cellular Handsets
  • Wireless PDAs

Description

The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z high-frequency step-down converters are optimized for dynamically powering the power amplifier (PA) in WCDMA or NCDMA handsets. The devices integrate a high-efficiency PWM step-down converter for medium- and low-power transmission, and a 60mΩ typical bypass FET to power the PA directly from the battery during high-power transmission. Dual 200mA low-noise, high-PSRR low-dropout regulators (LDOs) for PA biasing are also integrated.

Two switching frequency options are available (2MHz for the MAX8805W/MAX8805Y and 4MHz for the MAX8805X/MAX8805Z), allowing optimization for smallest solution size or highest efficiency. Fast switching allows the use of small ceramic 2.2µF input and output capacitors while maintaining low ripple voltage. The feedback network is integrated, further reducing external component count and total solution size.

The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z use an analog input driven by an external DAC to control the output voltage linearly for continuous PA power adjustment. The REFIN to OUT gain is available in two options (2V/V for the MAX8805Y/MAX8805Z and 2.5V/V for the MAX8805W/MAX8805X). At high-duty cycle, the MAX8805W/MAX8805X/MAX8805Y/MAX8805Z automatically switch to the bypass mode, connecting the input to the output through a low-impedance (60mΩ typ) MOSFET. The user can also enable the bypass mode directly through a logic-control input.

The LDOs in the MAX8805W/MAX8805X/MAX8805Y/MAX8805Z are designed for low-noise operation (35µVRMS typ). Each LDO is individually enabled through its own logic control interface.

The MAX8805W/MAX8805X/MAX8805Y/MAX8805Z are available in a 16-bump, 2mm x 2mm WLP and UCSP™ packages (0.7mm max height).

Simplified Block Diagram

MAX8805Y, MAX8805Z MAX8805Y, MAX8805Z Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .