Intersil ISL54222A高速USB信号连接方案

Intersil 公司的ISL54222A是单电源双2:1复接器,工作电压1.8V-3.3V,包括有两个SDPT开关,可配置成DPDT,开关导通电阻5.7欧姆,-3dB带宽为780MHz,能通过0-3.3VUSB全速(12MHz)数据信号和0-400mV USB高速(480MHz)数据信号(单电源1.8V电压),广泛应用在MP3和其它手提媒体播放器,手机,PDA,数码相机和摄像机以及USB交换.本文介绍了ISL54222A主要特性和应用方框图,以及ISL54222AIRUEVAL1Z评估板主要特性和电路图.

The Intersil ISL54222A is a single supply dual 2:1 multiplexer that can operate from a single 1.8V to 3.3V supply. It contains two SPDT (Single Pole/Double Throw) switches configured as a DPDT. The part was designed for switching or routing of USB High-Speed signals and/or USB Full-speed signals in portable battery powered products.

The 5.7Ω switches can swing rail-to-rail and were specifically designed to pass USB full speed data signals that range from 0V to 3.3V and USB high speed data signals that range from 0V to 400mV with a single supply as low as 1.8V. They have high bandwidth and low capacitance to pass USB high speed data signals with minimal distortion.

The part can be used in Personal Media Players and other portable battery powered devices that need to route USB high-speed signals or full-speed signals to different transceiver sections of the device while connected to a single USB host (computer).

The digital logic inputs are 1.8V logic compatible when operated with a 1.8V to 3.3V supply. The ISL54222A has an output enable pin to open all the switches and puts the part in a low power state. It can be used to facilitate proper bus disconnect and connection when switching between the USB sources.

The ISL54222A is available in 10 Ld 1.8mmx1.4mm μTQFN, 10 Ld 2.1mmx1.6mm μTQFN, 10 Ld TDFN and 10Ld MSOP packages. It operates over a temperature range of -40° to +85℃.

ISL54222A主要特性:

• High-Speed (480Mbps) and Full-Speed (12Mbps) Signaling Capability per USB 2.0

• 1.8V Logic Compatible

• Low Power All Off State

• Power OFF Protection

• D-/D+ Pins Overvoltage Tolerant to 5.5V

• -3dB Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . 780MHz

• Low ON Capacitance. . . . . . . . . . . . . . . . . . . . . . . . 6.7pF

• Low ON-Resistance. . . . . . . . . . . . . . . . . . . . . . . . . . 5.7Ω

• Single Supply Operation (VDD) . . . . . . . . . . . . 1.8V to 3.3V

• Available in μTQFN, TDFN, MSOP Packages

• Pb-Free (RoHS Compliant)

• Compliant with USB 2.0 Short Circuit and Overvoltage Requirements Without Additional External Components

• HBM ESD Performance I/O to GND . . . . . . . . . . . >12kV

ISL54222A应用:

• MP3 and other Personal Media Players

• Cellular/Mobile Phones

• PDA’s

• Digital Cameras and Camcorders

• USB Switching


图1.ISL54222A应用方框图

ISL54222AIRUEVAL1Z评估板

The ISL54222AIRUEVAL1Z evaluation board is designed to provide a quick and easy method for evaluating the ISL54222A USB Switch IC.

The ISL54222A device is a unique IC. To use this evaluation board properly requires a thorough knowledge of the operation of the IC. Refer to the data sheet for an understanding of the functions and features of the device.

Studying the device’s truth-table along with its pinout diagram in the data sheet is the best way to get a quick understanding of how the part works. The ISL54222A μTQFN IC is soldered onto the evaluation board. It is located in the center of the board and is designated as U1. The evaluation board contains USB connectors to allow the user to easily interface with the IC to evaluate its functions, features, and performance. For example, with the board properly powered and configured as shown in Figure 2, you can control the logic pins, SE and OE, to switch between the two high-speed USB devices while connected to a single USB host (computer).

In a typical application, the ISL54222A dual SPDT device is used to select between two different USB transceiver sections of a media player. Logic control from a μprocessor determines which section to connect to the computer. To change channels, the following sequence would possibly be followed:

1. A signal would be sent to take the OE pin High, to open all switches. The off-isolation of the ISL54222A device would allow the present active channel to properly disconnect from the computer.

2. The SEL pin would be set to select the other USB channel.

3. The OE pin would then be taken Low to close the switches to make the connection between the computer and the other USB section of the player.

ISL54222AIRUEVAL1Z评估板主要特性:

• Standard USB Connectors

• Standard Banana Jacks for Power, Ground, VBUS and Logic Connections

• Jumpers to Allow a Device to be Powered Through the Host Controller

• Convenient Test Points and Connections for Test Equipment



图2.ISL54222AIRUEVAL1Z评估板外形图

图3.ISL54222AIRUEVAL1Z评估板电路图