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PWM Buck Converters with Bypass FET for N-CDMA/W-CDMA Handsets

Next-Generation Dynamic CDMA/W-CDMA PA Step-Down Converters Integrate Bypass FET for Efficiency and Longest Battery Life in N-CDMA/W-CDMA Handsets

Product Details

Key Features

Simplified Block Diagram

Technical Docs

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Key Features

  • Integrated Bypass PFET
  • 150mV Dropout at 600mA Load (Regardless of External Inductor)
  • Dynamically Adjustable Output from 0.4V to VBATT
  • Externally Fixed Output from 1.25V to 2.5V with Digitally Controlled High-Power Bypass Mode (MAX8504)
  • 1MHz Fixed-Frequency PWM Switching
  • 600mA Guaranteed Output Current
  • 10% to 100% Duty-Cycle Operation
  • Low Quiescent Current
    • 280µA (typ) in Normal Mode
    • 3.3mA (typ) in PWM Mode
    • 0.1µA (typ) in Shutdown Mode
  • 12-Pin Thin QFN (4mm x 4mm, 0.8mm max Height)

Applications/Uses

  • NCDMA/WCDMA Cellular Phones
  • Wireless PDAs and Modems

Description

The MAX8500-MAX8504 PWM DC-to-DC buck converters are optimized with integrated bypass FET (0.25Ω typ) to provide power to the PA in N-CDMA and W-CDMA cell phones. The devices have a low on-resistance FET to bypass the external inductor for low dropout of only 150mV at 600mA load, regardless of inductor series resistance. The supply voltage range is from 2.6V to 5.5V and the guaranteed converter output current is 600mA. The 1MHz PWM switching frequency allows for small external components.

The MAX8500-MAX8503 are dynamically controlled to provide varying output voltages from 0.4V to VBATT. The LDO regulation point is slightly lower than the PWM converter such that the transition into and out of dropout is smooth, regardless of the inductor resistance. The MAX8504 is programmed for fixed 1.25V to 2.5V output with external resistors. It features a high-power bypass mode that connects the output directly to the battery. All devices are designed to achieve an output settling time of less than 30µs for a full-scale change in output voltage and load current.

The MAX8500-MAX8504 are available in a 12-lead 4mm x 4mm thin QFN package (0.8mm max height).

Simplified Block Diagram

MAX8500, MAX8503, MAX8504: Pin Configuration MAX8500, MAX8503, MAX8504: Pin Configuration 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 .

Sampling:
Selecting the Sample button above will redirect to the third-party ADI Sample Site. The part selected will carry over to your cart on this site once logged in. Please create a new account there if you have never used the site before. Contact SampleSupport@analog.com with any questions regarding this Sample Site.