Datasheet
2010 - 2015 Microchip Technology Inc. DS00001692C-page 19
USB251xB/xBi
5.0 INITIAL INTERFACE/CONFIGURATION OPTIONS
The hub must be configured in order to correctly function when attached to a USB host controller. The hub can be con-
figured either internally or externally by setting the CFG_SEL[1:0] pins (immediately after RESET_N negation) as out-
lined in the table below.
To configure the hub externally, there are two principal ways to interface to the hub: over SMBus or I
2
C EEPROM. The
hub can be configured internally, where several default configurations are available as described in the table below.
When configured internally, additional configuration is available using the strap options (listed in Section 3.3.1 on page
14).
5.1 Internal Register Set (Common to I
2
C EEPROM and SMBus)
The register set available when configuring the hub to interface over I
2
C or SMBus is outlined in the table below. Each
register has R/W capability, where EEPROM reset values are 0x00. Reserved registers should be written to 0 unless
otherwise specified. Contents read from unavailable registers should be ignored.
Note: See Chapter 11 (Hub Specification) of the USB specification for general details regarding hub operation
and functionality.
Note: Strap options are not available when configuring the hub over I
2
C or SMBus.
TABLE 5-1: INITIAL INTERFACE/CONFIGURATION OPTIONS
CFG_SEL[1] CFG_SEL[0] Description
0 0 Default configuration:
• Strap options enabled
• Self-powered operation enabled
• Individual power switching
• Individual over-current sensing
0 1 The hub is configured externally over SMBus (as an SMBus slave
device):
• Strap options disabled
• All registers configured over SMBus
1 0 Default configuration with the following overrides:
• Bus-powered operation
1 1 The hub is configured over 2-wire I
2
C EEPROM:
• Strap options disabled
• All registers configured by I
2
C EEPROM
Address Register Name
Default ROM Values
(Hexidecimal)
USB2512B/12Bi
USB2513B/13Bi
USB2514B/14Bi
00h Vendor ID LSB 24
01h Vendor ID MSB 04
02h Product ID LSB 12 13 14
03h Product ID MSB 25
04h Device ID LSB B3
05h Device ID MSB 0B