Compaq 850 manual USB Cable Data, USB Connector Pinout, USB Cable Length Data

Technical Reference Guide

5.7.3 USB CONNECTOR

Four series-A connectors are accessible on the rear panel of the chassis.

1 2 3 4

Figure 5-8.Universal Serial Bus Connector

Table 5–19. USB Connector Pinout

Table 5-19.

USB Connector Pinout

Pin	Signal	Description	Pin	Signal	Description
1	Vcc	+5 VDC	3	USB+	Data (plus)
2	USB-	Data (minus)	4	GND	Ground

5.7.4 USB CABLE DATA

The recommended cable length between the host and the USB device should be no longer than sixteen feet for full-channel (12 MB/s) operation, depending on cable specification (see following table).

Table 5–20. USB Cable Length Data

Table 5-20.

USB Cable Length Data

Conductor Size	Resistance	Maximum Length
20 AWG	0.036 Ω	16.4 ft (5.00 m)
22 AWG	0.057 Ω	9.94 ft (3.03 m)
24 AWG	0.091 Ω	6.82 ft (2.08 m)
26 AWG	0.145 Ω	4.30 ft (1.31 m)
28 AWG	0.232 Ω	2.66 ft (0.81 m)

NOTE:

For sub-channel (1.5 MB/s) operation and/or when using sub-standard cable shorter lengths may be allowable and/or necessary.

The shield, chassis ground, and power ground should be tied together at the host end but left unconnected at the device end to avoid ground loops.

Color code:

Signal	Insulation color
Data +	Green
Data -	White
Vcc	Red
Ground	Black

Compaq Deskpro EXS and Workstation 300 Personal Computers 5-25

Featuring the Intel Pentium 4 Processor

First Edition - December 2000