Connect-Tek USB-16 Manual do Utilizador descarregar pdf (Página 7)

Host High Speed Electrical Test Procedure Revision 1.4

on this computer is Windows 2000 or XP Professional. Please refer to the High-speed Electrical

Test Setup Instruction for steps to configure this computer.

Note: The Tektronix USB compliance test software operates internally to the oscilloscope and

automatically configures the oscilloscope settings so that external GPIB control of the

oscilloscope is not required. One can consolidate the High-speed Signal Quality Analysis

Computer and the High-speed USB Test Bed Computer into one single PC.

3.1 Equipment Setup

3.1.1 Test Equipment Setup Diskettes

Some tests described in this procedure are not automated by the Tektronix TDSUSB2

Compliance Test Software application. For those tests, the application includes setup files for the

test equipment used in this procedure. The setup files simplify equipment setup. Copy the HS

Scope Setup files to floppy disks. Insert the Tektronix TDS7000/6000, DPO7000/6000 setup

floppy diskette into the Tektronix TDS7254/7404, DPO7254/7354/7404, or TDS/DPO6000

oscilloscopes.

3.1.2 Digital Sampling Oscilloscope

Before turning on the oscilloscope, attach a P6330 or P6248 differential probe to Channel 1 and

Channel 4. TPA-BNC adaptors are required for the DPO7000 series. Attach two P6245 FET

probes, one to Channel 2 and one to Channel 3. The probe assignment will be used through out

the entire test procedure. Turn on the oscilloscope to allow for 20 minutes of warm up time prior

to use. Perform the signal path compensation procedure built into the Utility menu of the

Tektronix oscilloscope if the ambient temperature has changed more than 5 degrees. The

compensation should be performed with the probes disconnected from the oscilloscope.

A higher resolution view of the USB signaling is possible by turning on the scope’s Hi

Resolution mode. On the scope’s menu bar, select Horiz/acq > Horizontal/Acquisition Setup >

Acquisition > Hi Res.

The two single-end FET probes must be calibrated to minimize gain and offset errors. The offset

errors of the diff probes will be cancelled later as a part of the test procedure process. The offset

of the differential probe will be adjusted by the step identified in the test procedure.

For P6247/P6248 differential probes, the following setting will be used through out the entire test

procedure:

ο DC Reject <OFF> (P6247 only)

ο BW <Full> (P6247 only)

ο Attenuation <÷1>

The use of a Tip Saver accessory on the P6247 or P6248 probe is highly recommended to prolong

probe tip life. Please note that the Tip Saver will wear out after repeated use and start degrading

signal quality measurements. Replace the Tip Saver when measurements made without it provide

better results.

Note: In certain test situation, there may not be a ground connection between the DSO and the

device under test. This may lead to the signal seen by the differential probe to be modulated up

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Connect-Tek USB-16 Manual do Utilizador Página 7