GX4002 Datasheet, PDF (30/74 Pages) Gennum Corporation – Dynamic on-chip power management control

3.5.2.1 Ch1 LOS Threshold
The LOS assert threshold is set using the following registers. Apart from setting the assert
thresholds, these registers also set the temperature coefficient. Through weighted
summing of the CH1LOSTHNEG[7:0] and CH1LOSTHPOS[7:0] values, a range of
temperature coefficients can be achieved to ensure consistent LOS operation over
temperature:
Register Name
CH1_REG9
CH1_REG10
Register
Address^d
56
57
Parameter Name
CH1LOSTHNEG
CH1LOSTHPOS
Bit
Position
Access
7:0
RW
7:0
RW
Reset Value^b
10000011
00010001
Valid
Range^d
Function
0-255
0-255
Negative temperature coefficient LOS
threshold setting.
Positive temperature coefficient LOS
threshold setting.
Figure 3-12 to Figure 3-15 show the typical recommended range of CH1LOSASSERT
thresholds and corresponding CH1LOSTHNEG[7:0] setting to achieve these thresholds.
It is recommended to keep CH1LOSPOS[7:0] = 0. The CH1LOSDEASSERT thresholds
are the same as the CH1LOSASSERT thresholds for a hysteresis setting of 0.
CH1LOSHYS = 0
CH1LOSHYS = 9
CH1LOSHYS = 15
700
600
0dB
500
3.5dB
400
6dB
300
200
100
0
0
50
100
150
200
250
300
CH1LOSTHNEG
Figure 3-12: Ch1 LOS Threshold vs. Hysteresis (CH1LOSRANGE = 0)
CH1LOSHYS = 0
CH1LOSHYS = 9
CH1LOSHYS = 15
160
140
120
100
80
60
40
20
0
0
50
100
150
200
250
300
CH1LOSTHNEG
Figure 3-13: Ch1 LOS Threshold vs. Hysteresis (CH1LOSRANGE = 1)
GX4002 2x2 14.025Gb/s Crosspoint Switch with Trace
Equalization and Output De-Emphasis
Data Sheet
55972 - 0
March 2012
30 of 74
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