MPC8378E datasheet(14/128 Pages) FREESCALE

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MPC8378E PowerQUICC II Pro Processor Hardware Specifications, Rev. 8

Freescale Semiconductor

4.2

AC Electrical Characteristics

The primary clock source for the device can be one of two inputs, CLKIN or PCI_CLK, depending on

whether the device is configured in PCI host or PCI agent mode. This table provides the clock input

(CLKIN/PCI_CLK) AC timing specifications for the device.

4.3

eTSEC Gigabit Reference Clock Timing

This table provides the eTSEC gigabit reference clocks (EC_GTX_CLK125) AC timing specifications.

Table 8. CLKIN AC Timing Specifications

Parameter

Symbol

Min

Typical

Max

Unit

Note

CLKIN/PCI_CLK frequency

fCLKIN

—

66.666

MHz

1, 6

CLKIN/PCI_CLK cycle time

tCLKIN

—

CLKIN/PCI_CLK rise and fall time

tKH, tKL

0.6

1.0

2.3

CLKIN/PCI_CLK duty cycle

tKHK/tCLKIN

—

CLKIN/PCI_CLK jitter

—

± 150

4, 5

Notes:

1. Caution: The system, core and security block must not exceed their respective maximum or minimum operating

frequencies.

2. Rise and fall times for CLKIN/PCI_CLK are measured at 0.4 V and 2.7 V.

3. Timing is guaranteed by design and characterization.

4. This represents the total input jitter-short term and long term-and is guaranteed by design.

5. The CLKIN/PCI_CLK driver’s closed loop jitter bandwidth should be < 500 kHz at –20 dB. The bandwidth must be set low

to allow cascade-connected PLL-based devices to track CLKIN drivers with the specified jitter.

6. Spread spectrum is allowed up to 1% down-spread on CLKIN/PCI_CLK up to 60 KHz.

Table 9. EC_GTX_CLK125 AC Timing Specifications

At recommended operating conditions with LVDD = 2.5 ± 0.125 mV/ 3.3 V ± 165 mV

Parameter/Condition

Symbol

Min

Typical

Max

Unit

Note

EC_GTX_CLK125 frequency

tG125

—

125

—

MHz

—

EC_GTX_CLK125 cycle time

tG125

—8

—

EC_GTX_CLK rise and fall time

LVDD = 2.5 V

LVDD = 3.3 V

tG125R/tG125F

——

0.75

1.0

EC_GTX_CLK125 duty cycle

1000Base-T for RGMII, RTBI

tG125H/tG125

—

EC_GTX_CLK125 jitter

—

±150

Notes:

1. Rise and fall times for EC_GTX_CLK125 are measured from 0.5 and 2.0 V for LVDD = 2.5 V and from 0.6 and 2.7 V for

LVDD =3.3 V.

2. EC_GTX_CLK125 is used to generate the GTX clock for the eTSEC transmitter with 2% degradation. The

EC_GTX_CLK125 duty cycle can be loosened from 47%/ 53% as long as the PHY device can tolerate the duty cycle

generated by the eTSEC GTX_CLK. See Section 8.3.4, “RGMII and RTBI AC Timing Specifications,” for the duty cycle for

10Base-T and 100Base-T reference clock.

MPC8378E Datasheet(PDF) 14 Page - Freescale Semiconductor, Inc

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