Cautions For Each Test; El_22; Full-Speed Signal Quality; Compliance Test For Host Systems With S2R72A21 - Epson S2R72A21 Application Note

6. HS memory connected EXT port would be replaced to Host test fixture.
7. The Eye pattern is acquired via Oscilloscope (using a USB evaluation tool)
During this period, please check whether the LED2 (STAT0) is lighting. If the LED2 (STAT0) is not lighting,
the S2R72A21 is not under HS state so it is not possible to acquire eye pattern correctly.
When outputting the Test J/K, basically the procedures are similar as above. Please select either TEST_J or
TEST_K within the Port Control (above procedure-4). When you press EXECUTE on procedure-5, either
High-Speed J or K is output via the S2R72A21's EXT port.
6.4

Cautions for each test

6.4.1

EL_22

The EL_22 is a test specified in the USB 2.0 Electrical Compliance Test. When the compliance test is carried out
as Host, the EL_22 tests the response period to the HS packet which the Host received from the Device.
As stated on section 6.3 of the data sheet, a packet delay would occur during HS packet re-synchronization.
When the system with S2R72A21 is tested as a Host, the total period of the Host Controller's response and the
round-trip delay of S2R72A21 would be observed as the total system's period. Due to this, there would be a
possibility exceeding the max response period of 192 bit times (stated on the EL_22).
Detail would be explained on the separate document shown below.
6.4.2

Full-speed Signal Quality

The Full-speed Signal Quality is a test specified in the USB 2.0 Electrical Compliance Test. The signal quality of
FS packet output from the downstream port is measured in case the system is tested as Host.
The FS signal quality is affected by the impedance elements on the whole bus, such as BC Regulator, cable, and
on-resistance of S2R72A21's Bus Switch. Please evaluate on the actual system.
6.5

Compliance test for Host systems with S2R72A21

There is a separate document which explains the compliance test for Host systems which the S2R72A21are used.
Please contact our sales window in charge for this document "Compliance test for Host systems with S2R72A21"
before the compliance test.
S2R72A21 Application Note
(Rev.1.00)
Figure 6.3.2.6 Procedure-6 connection
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