Components

USB Type-C Port Switch with Low Distortion for Legacy Data and Analog Audio

Diodes Incorporated announced the PI3A6386 USB Type-C™ multimedia port switch. The company designed the USB Type-C port switch to enable continued support of legacy data and analog peripherals through USB Type-C ports.

Applications for the port switch include notebook PCs, cell phones, MP3 players, PDAs, and portable instrumentation.

With the adoption of USB Type-C ports in mobile phones and tablets, manufacturers are removing other ports, including USB 2.0 and 3.5mm audio sockets. The PI3A6386 port switch enables legacy data and audio signals to be passed through the USB Type-C port, allowing consumers to continue using existing peripherals.

PI3A6386 includes a dual, single-pole double throw (SPDT) switch for high-speed USB signal and high-quality audio signal. It can be utilized in USB Type-C D+/D- switching for USB signal in data mode and analog audio signal in audio accessory mode. The data path has a high USB bandwidth of 1GHZ for USH High-Speed signals.

Functional block diagram (Click on image to enlarge)

The PI3A6386 port switch performance ensures a high level of audio quality, without signal distortion or noise. It includes an autonomous microphone and ground line switching. The CMOS design delivers an ON resistance of 1Ω for the audio switching transistor. THD of -110dB is maintained from 20Hz to 20kHz with a signal of 2.0V RMS into a 32Ω load.

The device also features low crosstalk between data and audio channels with crosstalk rejection of -85dB at 30kHz. It also uses separate ground switches for the audio and data signals, to further minimize crosstalk. Programmable soft-start and soft-stop time eliminate the pop and click that audio signals can undergo when they are dc-coupled. Overall, the port switch delivers an audio experience free from distortion.

The PI3A6386 operates from a supply of between 1.7V and 5.5V, making it suitable for portable devices. It can also process signals of ±3V, which further improves the dynamic range and audio quality.

PI3A6386 can detect the microphone signals in SBU1 and SBU2, and automatically route them to the correct inputs of the microphone amplifier. Separate switches for microphone negative input and audio signal ground can minimize the crosstalk & echo between audio output signals and microphone input signals. Sideband switches can be configured to route SBU1 and SBU2 for sideband usage.

Features
  • Support USB High Speed (480Mbps) and Full Speed (12Mbps) Signaling Capability per USB 2.0
  • USB switches: High bandwidth (1GHz) & Low On-Resistance (5Ω)
  • Audio switches: Low On-Resistance (1Ω)
  • Support USB Type-C Audio Accessory Mode per USB Type-C Cable and Connector Specification 1.1
  • Low Distortion (THD: -110dB from 20Hz to 20kHz, 2.0VRMS, 32ohm load)
  • Negative Signal (+/-3V) Handling Capability
  • Programmable soft-start and soft-stop time to eliminate click/pop sounds of DC-coupled audio signals
  • High Off Isolation: -85dB @ 30kHz
  • Autonomous microphone and ground lines switching
  • Separate Ground switches for microphone and audio to minimize crosstalk
  • Sideband switches
  • I2C control
  • Wide VDD Range: 1.7V to 5.5V
  • ESD: 4Kv for HBM mode, 1kV for CDM mode
  • Extended Industrial Temperature Range: -40°C to 85°C

The PI3A6386 is available in the TQFN-24 package and priced at $0.68 in 3000 piece quantities.

Diodes Incorporated
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