USB 2.0 Full-Speed Transceiver with UART Multiplexing Mode

Use the Same Connector for USB and UART!


The MAX3349E ±15kV ESD-protected, USB transceiver provides a full-speed USB interface to a lower voltage microprocessor or ASIC. The device supports enumeration, suspend, and VBUS detection. A special UART multiplexing mode routes external UART signals (Rx and Tx) to D+ and D-, allowing the use of a shared connector to reduce cost and part count for mobile devices.

The UART interface allows mobile devices such as PDAs, cellular phones, and digital cameras to use either UART or USB signaling through the same connector. The MAX3349E features a separate UART voltage supply input to support legacy devices using +2.75V signaling. The MAX3349E supports a maximum UART baud rate of 921kbaud.

Upon connection to a USB host, the MAX3349E enters USB mode and provides a full-speed USB 2.0 compliant interface through VP, VM, RCV, and active-low OE. The MAX3349E features internal series termination resistors on D+ and D-, and an internal 1.5kΩ pullup resistor to D+ to allow the device to logically connect and disconnect from the USB while plugged in. A suspend mode is provided for low-power operation. D+ and D- are protected from electrostatic discharge (ESD) up to ±15kV.

The MAX3349E is available in 16-pin TQFN (4mm x 4mm) and 16-bump UCSP™ (2mm x 2mm) packages, and is specified over the -40°C to +85°C extended temperature range.
MAX3349E: Typical Operating Circuit MAX3349E: Typical Operating Circuit Enlarge+

Key Features

  • ±15kV ESD HBM Protection on D+ and D-
  • UART Mode Routes External UART Signals to D+/D-
  • Internal Linear Regulator Allows Direct Powering from the USB Cable
  • Separate Voltage Input for UART Transmitter/Receiver (VUART)
  • Internal 1.5kΩ Pullup Resistor on D+ Controlled by Enumerate Input
  • Internal Series Termination Resistors on D+ and D-
  • Complies with USB Specification Revision 2.0, Full-Speed 12Mbps Operation
  • Built-In Level Shifting Down to +1.4V, Ensuring Compatibility with Low-Voltage ASICs
  • VBUS Detection
  • Combined VP and VM Inputs/Outputs
  • No Power-Supply Sequencing Required
  • Available in 16-Bump UCSP (2mm x 2mm) Package


  • Cell Phones
  • Digital Cameras
  • MP3 Players
  • PDAs
Part Number VL
Supports USB Speed Internal USB Pullup Resistor ESD Protect.
1.5kΩ See Notes
MAX3349E  1.4 to 2.75 Full-Speed Yes 15 4.0 to 5.5 $1.40 @1k
See All USB Transceivers (12)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

Technical Documents

Tutorial 4686 Important Design Considerations for Heart-Rate and Fitness Monitors

Quality and Environmental Data

Product Reliability Reports: MAX3349E.pdf 
Lead-Free Package Tin (Sn) Whisker Reports

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