Datasheet

USB251xB/xBi
DS00001692C-page 22  2010 - 2015 Microchip Technology Inc.
5.1.7 REGISTER 06H: CONFIG_BYTE_1
Bit Number Bit Name Description
7 SELF_BUS_PWR Self or Bus Power: selects between self- and bus-powered operation.
The hub is either self-powered (draws less than 2 mA of upstream bus power)
or bus-powered (limited to a 100 mA maximum of upstream power prior to
being configured by the host controller).
When configured as a bus-powered device, the hub consumes less than
100 mA of current prior to being configured. After configuration, the bus-
powered hub, along with all associated hub circuitry, any embedded devices
(if part of a compound device), and all externally available downstream ports
(max 100 mA) must consume no more than 500 mA of upstream VBUS
current. The current consumption is system dependent and must not violate
the
USB 2.0 Specification [1].
When configured as a self-powered device, < 1 mA of upstream VBUS current
is consumed and all ports are available. Each port is capable of sourcing
500 mA of current.
This field is set over either the SMBus or I
2
C EEPROM interface options.
0 : bus-powered operation
1 : self-powered operation
If dynamic power switching is enabled (Section 5.1.8), this bit is ignored and
LOCAL_PWR is used to determine if the hub is operating from self or bus
power.
6 rsvd
5 HS_DISABLE Hi-Speed Disable: disables the capability to attach as either a hi- or full-speed
device, forcing full-speed attachment only (i.e., no hi-speed support).
0 : hi-/full-speed
1 : full-speed only (hi-speed disabled)
4 MTT_ENABLE Multi-TT Enable: enables one transaction translator per port operation.
Selects between a mode where only one transaction translator is available for
all ports (single-TT), or each port gets a dedicated transaction translator
(multi-TT).
0 : single TT for all ports
1 : multi-TT (one TT per port)
3 EOP_DISABLE EOP Disable: disables End Of Packet (EOP) generation at End Of Frame
Time #1 (EOF1) when in full-speed mode.
During full-speed operation only, the hub can send EOP when no downstream
traffic is detected at EOF1. See the
USB 2.0 Specification, Section 11.3.1 for
details.
0 : EOP generation is normal
1 : EOP generation is disabled
2:1 CURRENT_SNS Over-Current Sense: selects current sensing on all ports (ganged); a port-by-
port basis (individual); or none (for bus-powered hubs only). The ability to
support current sensing on a ganged or port-by-port basis is hardware
implementation dependent.
00 : ganged sensing
01 : individual sensing
1x : over-current sensing not supported (use with bus-powered configurations)
0 PORT_PWR Port Power Switching: enables power switching on all ports (ganged) or a port-
by-port basis (individual). The ability to support power enabling on a ganged
or port-by-port basis is hardware implementation dependent.
0 : ganged switching
1 : individual switching