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GS6151

Final Data Sheet

Rev.4

PDS-060389

August 2015

19 of 77

Semtech

Proprietary & Confidential

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The method of strength detection is measurement of the average rectified differential

voltage on the input pins. The strength detection method is therefore inherently

dependent on the input signal's eye shape, particularly the rise/fall times of the input

signal relative to the data rate. Additionally, the circuit has a lower bandwidth limit of

operation (20Mb/s) below which it is recommended that the edge detection method is

used. The absolute value of the threshold can be determined for any input swings

according to Equation 4-1 below:

Equation 4-1

where DEVICE_SPECIFIC_LOS_THRESHOLD specifies the LOS threshold value for a

100mV input swing at SD-rate specific to each device. The other rates scale according to

the fractional relationship given in Figure 4-1 and Figure 4-2 below.

Figure 4-1: LOS Threshold at 100mV Input Swing vs. Low Frequency Rates for a Nominal

DEVICE_SPECIFIC_LOS_THRESHOLD of 53

Note: Edge detection method is recommended for signals in shaded areas.

Threshold

1.9mV

DDI[0..3]_LOS_THRESHOLD_CONTROL

)

(

DEVICE_SPECIFIC_LOS_THRESHOLD

()

-----------------------------------------------------------------------------------------------------------------------------------------

100

120

Frequency (Mb/s)

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