GX4002 Datasheet, PDF (29/74 Pages) Gennum Corporation – Dynamic on-chip power management control

3.5.2 Ch1 Loss Of Signal
The Ch1 Loss Of Signal (LOS) indicator status is available through a register and the
Ch1LOS pin. The Ch1LOS pin is by default open-drain, active-high. However, the pin
can be configured in a LVCMOS/LVTTL compatible mode by setting
OPENDRAINCH1LOS to 0. In addition, Ch1LOS can be configured to be active-low by
setting POLINVCH1LOS HIGH. The status of Ch1LOS can be read out through
CH1PLLLOS.
Register Name
Register
Address^d
TOP_REG2
2
CH1PLL_REG10
29
Parameter Name
POLINVCH1LOS
OPENDRAINCH1LOS
CH1PLLLOS
Bit
Position
Access
1:1
RW
2:2
RW
0:0
RO
Reset Value^b
0
1
0
Valid
Range^d
Function
0-1
When HIGH, inverts polarity of Ch1LOS
output.
0-1
When HIGH, makes Ch1LOS output driver
open-drain.
0-1
Ch1 CDR loss of signal when HIGH.
The LOS assert threshold can be set from 5mV to 400mV in three distinct ranges. The LOS
assert threshold is a function of the CH1LABOOST setting. Figure 3-8 describes the
selection of CH1LOSRANGE based on the required LOS assert threshold and
CH1LABOOST settings.
Register Name
CH1_REG14
Register
Address^d
61
Parameter Name
CH1LOSRANGE
Bit
Position
Access
2:0
RW
Reset Value^b
001
Valid
Range^d
Function
0-7
1:0 - LOS range 0: highest - 3: lowest, 2
(MSB) unused.
Table 3-8: LOS Assert Ranges
CH1LABOOST
[3:0]
LOS Assert Threshold Range
Min
Max
0-7
0-7
0-7
0-7
8-15
8-15
8-15
8-15
5
400
—
—
5
30
30
100
100
400
5
30
30
100
—
—
100
400
CH1LOSRANGE
[1:0]
LOS Threshold -
Total Range
11 - Unused
10 - Low Range
01 - Mid Range
00 - High Range
11 - Low Range
10 - Mid Range
01 - Unused
00 - High Range
Resolution
(controlled by
CH1LOSTHNEG/POS)
—
—
<0.1mV
<1.0mV
<2.0mV
<0.1mV
<1.0mV
—
<2.0mV
Unit
mVppd
—
mVppd
mVppd
mVppd
mVppd
mVppd
—
mVppd
GX4002 2x2 14.025Gb/s Crosspoint Switch with Trace
Equalization and Output De-Emphasis
Data Sheet
55972 - 0
March 2012
29 of 74
Proprietary & Confidential