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Philips Semiconductors
ISP1122
USB stand-alone hub
Product specification Rev. 03 — 29 March 2000 17 of 48
9397 750 07002
© Philips Electronics N.V. 2000. All rights reserved.
[1] ISP1122 always reports power management status on an individual basis, even for ganged/global
modes. This is compliant with
USB Specification Rev. 1.1
.
[2] Condition with no overcurrent detection is reported to the host.
[3] Value in units of 2 ms.
[1] Unicode encoded string.
Table 14: Hub descriptor
Values in square brackets are optional.
Offset
(bytes)
Field name Size
(bytes)
Value
(Hex)
Comments
0 bDescLength 1 09 descriptor length=9bytes
1 bDescriptorType 1 29 type = HUB
2 bNbrPorts 1 05 to 02 number of enabled downstream ports;
selectable by DP/DM strapping
3 wHubCharacteristics 2 09, 00 individual power switching
[1]
,
overcurrent protection active
(modes 0, 1, 3, 4, 5, 7)
11, 00 individual power switching
[1]
, no
overcurrent protection (modes 2, 6)
[2]
5 bPwrOn2PwrGood
[3]
1 32 100 ms (default; modes 0, 1, 2, 4, 5, 6)
00 0 ms (default; modes 3, 7)
[FA] 500 ms (using an external EEPROM;
modes 0, 1, 2, 4, 5, 6); see Table 23
6 bHubContrCurrent 1 64 maximum hub controller current
(100 mA)
7 DeviceRemovable 1 00 all devices removable
8 PortPwrCtrlMask 1 FF must be all ones for compatibility with
USB Specification Rev. 1.0
Table 15: String descriptors
String descriptors are optional and therefore disabled by default; they can be enabled through
an external EEPROM.
Offset
(bytes)
Field name Size
(bytes)
Value
(Hex)
Comments
String descriptor (0): language ID string
0 bLength 1 04 descriptor length=4bytes
1 bDescriptorType 1 03 type = STRING
2 bString 2 09, 04 LANGID code zero
String descriptor (1): manufacturer string
0 bLength 1 2E descriptor length = 46 bytes
1 bDescriptorType 1 03 type = STRING
2 bString 44 UC
[1]
“Philips Semiconductors”
String descriptor (2): product string
0 bLength 1 10 descriptor length = 16 bytes
1 bDescriptorType 1 03 type = STRING
2 bString 14 UC
[1]
“ISP1122”