STMicroelectronics STV-676/501C-R01, Руководство пользователя

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STV0676 Design issues
6.3 USB Compliance eye test
To ensure that the STV0676 still operates within the USB signal integrity compliance limits when
used with long (i.e. 5m) USB cables, the following circuit may be required.
Full compliance can be guaranteed by adding the circuitry shown in
Figure 8
into each of the USB
data lines (DP and DN) between the STV0676 and the USB connector.
Note: USB compliance
If a USB product has a tethered USB cable, the USB compliance testing is done with this cable only.
If the tethered cable is short (2m or less), the above circuit should not be required.
If a USB product is fitted with a socket for a separate USB cable, the USB compliance testing is
done with the maximum allowable USB cable length of 5m. In this case the external circuitry from
Figure 8 may be necessary to achieve full USB compliance.
Figure 8: USB compliance circuitry
from STV0676
to USB
gnd
3v3
npn
pnp
10R
10R