MPC875 datasheet(67/84 Pages) FREESCALE

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MPC875/MPC870 Hardware Specifications, Rev. 3.0

PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE

Freescale Semiconductor

USB Electrical Characteristics

Figure 63 shows the I2C bus timing.

Figure 63. I2C Bus Timing Diagram

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 30 lists the USB interface timings.

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.

15.1 MII and Reduced MII Receive Signal Timing

The receiver functions correctly up to a MII_RX_CLK maximum frequency of 25 MHz +1%. The reduced MII

(RMII) receiver functions correctly up to a RMII_REFCLK maximum frequency of 50 MHz + 1%. There is no

minimum frequency requirement. In addition, the processor clock frequency must exceed the MII_RX_CLK

frequency – 1%.

Table 30. USB Interface AC Timing Specifications

Name

Characteristic

All Frequencies

Unit

Min

Max

US1

USBCLK frequency of operation 1

Low speed

Full speed

1 USBCLK accuracy should be ± 500 ppm or better. USBCLK may be stopped to conserve power.

MHz

US4

USBCLK duty cycle (measured at 1.5 V)

SCL

202

205

203

207

204

208

206

209

211

210

SDA

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