The MAX3349EA ±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 MAX3349EA features a separate UART voltage supply input to support legacy devices using +2.75V signaling. The MAX3349EA supports a maximum UART baud rate of 921kbaud. Upon connection to a USB host, the MAX3349EA enters USB mode and provides a full-speed USB 2.0 compliant interface through VP, VM, RCV, and OE. The MAX3349EA 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 MAX3349EA 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.
The MAX3349EA provides a full‑speed USB 2.0 interface to low‑voltage microprocessors or ASICs and includes a special UART multiplexing mode that routes external UART signals to the D+ and D‑ pins. It supports enumeration, suspend, VBUS detection, and can operate in either USB mode or UART mode depending on the presence of VBUS.
The device is offered in 16‑pin TQFN and 16‑bump UCSP packages, operates over –40 °C to +85 °C, and features internal series termination resistors, a 1.5 kΩ pull‑up on D+, and separate UART voltage supply. Electrical and timing characteristics are detailed for both USB and UART operation.
| ESD protection (D+, D‑) | ±15 kV |
|---|---|
| Operating temperature range | -40 °C to +85 °C |
| Maximum UART baud rate | 921 kbaud |
| VBUS input range (USB mode) | 4.0 V to 5.5 V |
| VUART input range (UART mode) | 2.7 V to 3.3 V |
| VL input range (logic supply) | 1.4 V to 2.75 V |
| Internal pull‑up resistor on D+ | 1.5 kΩ |
| Package options | 16‑pin TQFN (4 mm × 4 mm) and 16‑bump UCSP (2 mm × 2 mm) |
The device supports a maximum UART baud rate of 921 kbaud.
Both D+ and D‑ are protected against electrostatic discharge up to ±15 kV.
It is offered in a 16‑pin TQFN (4 mm × 4 mm) and a 16‑bump UCSP (2 mm × 2 mm) package.