TSI721 datasheet(40/67 Pages) RENESAS

40 / 67 page

Tsi721 Datasheet

April 4, 2016

Integrated Device Technology

Each signal swings between the voltages VHIGH and VLOW where:

VHIGH > VLOW

The differential voltage, VDIFF is defined as:

VDIFF = VD+ - VD-

where VD+ is the voltage on the positive conductor and VD- is the voltage on the negative conductor of a differential

transmission line. VDIFF represents either the differential output signal of the transmitter, VOD, or the differential input signal of

the receiver, VID where:

VOD = VTD - VTD

and

VID = VRD - VRD

The common mode voltage, VCM, is defined as the average or mean voltage present on the same differential pair. Therefore:

VCM = | VD+ + VD- | / 2

The maximum value, or the peak-to-peak differential voltage, is calculated on a per unit interval and is defined as:

VDIFFp-p = 2 x max | VD+ - VD- |

because the differential signal ranges from VD+ - VD- to -(VD+ - VD-)

To illustrate these definitions using real values, consider the case of a CML (Current Mode Logic) transmitter and each of its

outputs, TD and TD_N, has a swing that goes between VHIGH = 2.5V and VLOW = 2.0V, inclusive. Using these values the

common mode voltage is calculated to be 2.25 V and the single-ended peak voltage swing of the signals TD and TD_N is

500 mVpp. The differential output signal ranges between 500 mV and -500 mV, inclusive. therefore the peak-to-peak

differential voltage is 1000 mVppd.

TSI721 Datasheet(PDF) 40 Page - Renesas Technology Corp