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QRZ.RU > Технические справочники > HwB: The Hardware Book (Mirror) > HwB: Universal Serial Bus (USB) (Tech) Connector

HwB: Universal Serial Bus (USB) (Tech) Connector

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Universal Serial Bus (USB) (Technical)

USB was developed by Compaq, Digital Equipment Corp, IBM PC Co., Intel, Microsoft, NEC and Northern Telecom.

Features:

  • True Plug'n'Play.
  • Hot plug and unplug
  • Low cost
  • Easy of use
  • 127 physical devices
  • Low cost cables and connectors

Bandwidth:

  • Full speed: 12 Mbps speed (requires shielded cable)
  • Low speed: 1.5 Mbps speed (non-shielded cable)

Definitions:

USB Host = The computer, only one host per USB system.
USB Device = A hub or a Function.

Power usage:

Bus-powered hubs: Draw Max 100 mA at power up and 500 mA normally.
Self-powered hubs: Draw Max 100 mA, must supply 500 mA to each port.
Low power, bus-powered functions: Draw Max 100 mA.
High power, bus-powered functions: Self-powered hubs: Draw Max 100 mA, must supply 500 mA to each port.
Self-powered functions: Draw Max 100 mA.
Suspended device: Max 0.5 mA

Voltage:

  • Supplied voltage by a host or a powered hub ports is between 4.75 V and 5.25 V.
  • Maximum voltage drop for bus-powered hubs is 0.35 V from it's host or hub to the hubs output port.
  • All hubs and functions must be able to send configuration data at 4.4 V, but only low-power functions need to be working at this voltage.
  • Normal operational voltage for functions is minimum 4.75 V.

Shielding:

Shield should only be connected to Ground at the host. No device should connect Shield to Ground.

Cable:

Shielded:
Data: 28 AWG twisted
Power: 28 AWG - 20 AWG non-twisted

Non-shielded:
Data: 28 AWG non-twisted
Power: 28 AWG - 20 AWG non-twisted

Power Gauge Max length
28 0.81 m
26 1.31 m
24 2.08 m
22 3.33 m
20 5.00 m

Cable colors:

Pin Name Cable color Description
1 VCC Red +5 VDC
2 D- White Data -
3 D+ Green Data +
4 GND Black Ground
Contributor: Joakim Цgren
Sources: USB FAQ at USB Implementers Forum
Sources: USB Specification v1.0 at
USB Implementers Forum
Please send any comments to Joakim Цgren.

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