MPC8569E datasheet(79/127 Pages) FREESCALE

79 / 127 page

High-Speed SerDes Interfaces (HSSI)

MPC8569E PowerQUICC III Integrated Processor Hardware Specifications, Rev. 1

Freescale Semiconductor

Figure 38. Differential Voltage Definitions for Transmitter or Receiver

Using this waveform, the definitions are as shown in the following list. To simplify the illustration, the definitions assume that

the SerDes transmitter and receiver operate in a fully symmetrical differential signaling environment:

Single-Ended Swing

The transmitter output signals and the receiver input signals SD_TX, SD_TX, SD_RX and SD_RX

each have a peak-to-peak swing of A – B volts. This is also referred as each signal wire’s

single-ended swing.

Differential Output Voltage, VOD (or Differential Output Swing):

The differential output voltage (or swing) of the transmitter, VOD, is defined as the difference of

the two complimentary output voltages: VSD_TX – VSD_TX. The VOD value can be either positive

or negative.

Differential Input Voltage, VID (or Differential Input Swing):

The differential input voltage (or swing) of the receiver, VID, is defined as the difference of the two

complimentary input voltages: VSD_RX – VSD_RX. The VID value can be either positive or

negative.

Differential Peak Voltage, VDIFFp

The peak value of the differential transmitter output signal or the differential receiver input signal

is defined as the differential peak voltage, VDIFFp = |A – B| volts.

Differential Peak-to-Peak, VDIFFp-p

Since the differential output signal of the transmitter and the differential input signal of the receiver

each range from A – B to –(A – B) volts, the peak-to-peak value of the differential transmitter

output signal or the differential receiver input signal is defined as differential peak-to-peak voltage,

VDIFFp-p = 2 × VDIFFp = 2 × |(A – B)| volts, which is twice the differential swing in amplitude, or

twice of the differential peak. For example, the output differential peak-peak voltage can also be

calculated as VTX-DIFFp-p = 2 × |VOD|.

Differential Waveform

The differential waveform is constructed by subtracting the inverting signal (SD_TX, for example)

from the non-inverting signal (SD_TX, for example) within a differential pair. There is only one

signal trace curve in a differential waveform. The voltage represented in the differential waveform

is not referenced to ground. See Figure 43 as an example for differential waveform.

Common Mode Voltage, Vcm

The common mode voltage is equal to half of the sum of the voltages between each conductor of

a balanced interchange circuit and ground. In this example, for SerDes output,

Vcm_out =(VSD_TX +VSD_TX) ÷ 2 = (A + B) ÷ 2, which is the arithmetic mean of the two

complimentary output voltages within a differential pair. In a system, the common mode voltage

Differential Swing, VID or VOD = A – B

A Volts

B Volts

SDn_TX or

SDn_RX

SDn_TX or

SDn_RX

Differential Peak Voltage, VDIFFp = |A – B|

Differential Peak-Peak Voltage, VDIFFpp = 2 * VDIFFp (not shown)

Vcm = (A + B)/2

MPC8569E датащи(PDF) 79 Page - Freescale Semiconductor, Inc

MPC8569E датащи(HTML) 79 Page - Freescale Semiconductor, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

датащи скачать

ссылки URL