USB Electrical Characteristics
Figure 71 shows signal timings during UTOPIA transmit operations.
U1
U1
1
UtpClk
U2
5
PHSELn
TxClav
U3
3
U4
4
High-Z at MPHY
High-Z at Multi-PHYP
U2
2
TxEnb
UTPB
SOC
U2
5
Figure 71. UTOPIA Transmit Timing
14 USB Electrical Characteristics
This section provides the AC timings for the USB interface.
14.1 USB Interface AC Timing Specifications
The USB Port uses the transmit clock on SCC1. Table 33 lists the USB interface timings.
Table 33. USB Interface AC Timing Specifications
All Frequencies
Name
Characteristic
Unit
Min
Max
1
US1 USBCLK frequency of operation
Low speed
Full speed
6
48
MHz
MHz
US4 USBCLK duty cycle (measured at 1.5 V)
45
55
%
1 USBCLK accuracy should be ±500 ppm or better. USBCLK may be stopped to conserve power.
15 FEC Electrical Characteristics
This section provides the AC electrical specifications for the fast Ethernet controller (FEC). Note that the timing
specifications for the MII signals are independent of system clock frequency (part speed designation). Also, MII
signals use TTL signal levels compatible with devices operating at either 5.0 V or 3.3 V.
MPC885/MPC880 Hardware Specifications, Rev. 3
71
Freescale Semiconductor
FREESCALE [ Freescale ]
