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Part No.	USB251
Manufacturer	MICROCHIP
Size	810 Kbytes
Pages	57 pages
Description	USB 2.0 Hi-Speed Hub Controller

Datasheet Summary with AI

Overall Purpose:

The document excerpt describes the pinout, functionality, and configuration options for a USB 2.0 hub controller chip (the USB251xB/xBi). It details how various pins are used for USB communication, power management, configuration, and other features.

Key Sections & Highlights:

1. Upstream/Downstream USB Interfaces:
- `USBDM_UP`, `USBDP_UP`: Pins for connecting to the host or upstream hub (the device at the very top of the USB chain).
- `VBUS_DET`: Detects if power is being supplied from the upstream host. This is crucial for battery charging and power management.
- `USBDM_DN[x:1]`, `USBDP_DN[x:1]`: Pins for connecting to the USB devices plugged into the hub.
- `PRTPWR[x:1]`, `BC_EN[x:1]`: Power Enable pins for devices downstream.
- `OCS_N[x:1]`: Over-Current Sense input.

2. Serial Port Interfaces:
- `SDA`, `SMBDATA`, `NON_REM1`: Pins for serial communication and system management bus (SMBus).
- `RESET_N`: The reset input signal.
- `SCL`, `SMBCLK`, `CFG_SEL0`: Pins for serial clock and configuration selection.
- `HS_IND`, `CFG_SEL1`: High-speed indicator and configuration selection pin.

3. Miscellaneous Pins:
- `XTALIN`, `CLKIN`, `XTALOUT`: Pins for the crystal oscillator or external clock source.

Important Configuration Details (Key Points):

️· Configuration Selection (CFG_SEL0, CFG_SEL1): These pins are latched during reset and determine the configuration method of the hub (e.g., whether it's a single-speed or high-speed hub, and how it interacts with the host).
️· Port Disable (PRT_DIS_P[x:1], PRT_DIS_M[x:1]): These pins, when pulled high, disable a specific port on the hub.
️· Non-Removable Device Detection (NON_REM1): Indicates whether devices connected to a port are permanently attached.
️· Battery Charging (BC_EN[x:1]): Enables support for USB battery charging protocols.

Buffer Types:

The table introduces "Buffer Type" abbreviations:

️· I: Input
️· O: Output
️· OCLKx: Output Clock
️· ICLKx: Input Clock
️· IO: Input/Output
️· I/OSD12: Input/Output - Schmitt Trigger
️· IPU: Input with Pull-Up Resistor
️· I-R: Input with Resistor