SMSC USB2502

USB2502 일반적인 설명

The USB2502 2-port hub controller is fully compliant with the USB 2.0 Specification. When connected to a high-speed host, the two downstream facing ports can operate at low-speed (1.5Mb/s), full-speed (12Mb/s), or high-speed (480Mb/s). As required by the USB 2.0 Specification, the USB2502 is fully backward compatible with legacy full-speed hosts.

The USB2502 supports both bus-powered and self-powered configurations. For self-powered operation, an external supply is used to power the downstream facing ports. In bus-powered mode, all power is derived from the upstream facing port and no external power supply is required. An external USB power distribution switch device is used to control VBUS switching to downstream ports, and to limit current and sense over-current conditions.

A default configuration is available in the USB2502 following a reset. This configuration may be sufficient for some applications when it is desired to save the expense of an EEPROM. The controller may also be configured from a microcontroller or an external EEPROM. When using the microcontroller interface, the USB2502 appears as an SMBus slave device. The EEPROM interface supports a 2-wire I2C device.

All required resistors on the USB ports are integrated into the USB2502. This includes all series termination resistors on D+ and D- pins and all required pull-down and pull-up resistors on D+ and D- pins. The over-current sense inputs for the downstream facing ports have internal pull-up resistors.
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특징

• Compliant with USB 2.0 Specification
• Hub Controller IC with Two Downstream Ports
• Enables Bus-Powered Hi-Speed Hub Design
• Default Configuration with Pin Selectable Options
• Flexible OEM Configuration Options
• 36 Pin QFN or 48 Pin TQFP RoHS compliant package
• Detects Removal of Self-Power and Automatically Changes Mode to Bus-Power
• Integrated Termination and Pull-Up/Pull-Down Resistors
• Internal Short Circuit Protection of DP and DM Lines
• On-Chip Oscillator Uses Low Cost 24MHz Crystal
• Supports Ganged Over-Current Protection and Power Control
• Customize Vendor ID, Product ID, and Device ID
• Operation as a bus-powered, self-powered or dynamic-powered hub (When configured for dynamic operation, the controller automatically switches to bus-powered mode if a local power source is unavailable)
• Select whether the hub is part of a compound device (When any downstream facing port is permanently hardwired to a USB peripheral device, the hub is part of a compound device)
• Select the presence of a permanently hardwired USB peripheral device on a port by port basis
• Configure the delay time for filtering the over-current sense inputs
• Configure the delay time until port power is good after receiving command to turn on downstream port power
• Indicate the maximum current that the 2-port hub consumes from an upstream port
• Indicate the maximum current required for the hub controller
• Select Operation as Either a Bus-Powered Hub or a Self-Powered Hub
• Select Downstream Port Power Control Polarity

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