2-Port USB 2.0 Hi-Speed Hub Controller
Datasheet
2014 Microchip Technology Inc.
DS00001726A-page 29
4.4.8
Configuration Data Byte 2 Register (CFG2)
Address:
Size:
8 bits
BITS
DESCRIPTION
TYPE
DEFAULT
7
Dynamic Power Enable (DYNAMIC)
Controls the ability of the Hub to automatically change from Self-Powered
operation to Bus- Powered operation if the local power source is removed
or is unavailable (and from Bus-Powered to Self-Powered if the local power
source is restored).
Note:
If the local power source is available, the Hub will always switch to
Self-Powered operation.
When Dynamic Power switching is enabled, the Hub detects the availability
of a local power source by monitoring the external LOCAL_PWR pin. If the
Hub detects a change in power source availability, the Hub immediately
disconnects and removes power from all downstream devices and
disconnects the upstream port. The Hub will then re-attach to the upstream
port as either a Bus-Powered Hub (if local-power is unavailable) or a Self-
Powered Hub (if local power is available).
0 = No Dynamic auto-switching
(pin becomes SUSP_IND) and the hub controller will utilize the inverse of
the SELF_BUS_PWR bit for 'Hub_Status_Field' bit '0' (local power source)
1 = Dynamic Auto-switching capable
(pin becomes LOCAL_PWR) and the hub controller will utilize the
LOCAL_PWR pin for 'Hub_Status_Field' bit '0' (local power source)
R/W
0b
6
RESERVED
-
-
5:4
Over Current Timer Delay (OC_TIMER)
00 = 0.1ms
01 = 4ms
10 = 8ms
11 = 16ms
R/W
00b
3
Compound Device (COMPOUND)
Allows the OEM to indicate that the Hub is part of a compound (see the USB
Specification for definition) device. The applicable port(s) must also be
defined as having a “Non-Removable Device”.
Note:
When configured via strapping options, declaring a port as non-
removable automatically causes the hub controller to report that it
is part of a compound device.
0 = No
1 = Yes, Hub is part of a compound device
R/W
0b
2:0
RESERVED
-
-
