GX3146 Datasheet, PDF (21/46 Pages) Semtech Corporation – Crosspoint Switch with Trace Equalization and Output De-emphasis

Table 4-1: Serial Data Input (Continued)
EQ_TERMINATION[287:0],
EXT_PG0_EQ_TERMINATION and
EXT_PG1_EQ_TERMINATION bits 3:3
0
1
EQ_POWERDOWN[287:0],
EXT_PG0_EQ_POWERDOWN and
EXT_PG1_EQ_POWERDOWN bits 4:4
0
1
Input Termination Common Mode Point Switch to
VCC_IN_1, VCC_IN_2
Open (see Figure 3-1)
Closed (see Figure 3-1)
Equalizer Power
On
Off
4.2 Serial Data Output
Each of the GX3146 SDI outputs have two on-chip 50Ω single-ended terminations, and
can be programmed to output differential amplitudes of 200mVppd, 400mVppd or
800mVppd when the corresponding VCC_OUT1 or VCC_OUT2 is connected to either
1.2V or 1.8V, or 200mVppd, 400mVppd, 800mVppd, or 1200mVppd when the
corresponding VCC_OUT1 or VCC_OUT2 is connected to 2.5V. The selection of the
output swing is made using the corresponding OUTPUT_SWING_SET[287:0],
MON0_OUTPUT_SWING_SET or MON1_OUTPUT_SWING_SET bits, shown in
Table 4-3.
If the HIGH_OP_V bit is set when either the VCC_OUT1 or VCC_OUT2 supplies are 1.2V
or 1.8V, the 800mVppd swing setting is no longer valid for that output bank. Swing
settings for an output bank connected to a 2.5V supply are unaffected.
Table 4-2: HIGH_OP_V Swing Selection
VCC_OUTx
Supply Voltage (V)
HIGH_OP_V = 0
Valid Output Swing
Selection (mVppd)
HIGH_OP_V = 1
Valid Output Swing
Selection (mVppd)
Note
1.2
200, 400, 800
200, 400
1
1.8
200, 400, 800
200, 400
—
2.5
200, 400, 800
200, 400, 800, 1200
2
Notes:
1. For an 800mVppd output swing when the corresponding VCC_OUT1 or VCC_OUT2 is connected to
1.2V, the output must be DC-coupled to a receiving device terminated to 1.2V.
2. When VCC_OUT1 or VCC_OUT2 is set to 2.5V, the HIGH_OP_V bit must be set to enable 1200mVppd
swing selection.
Each of the 146 SDI output channels provide independently programmable
de-emphasis, to compensate from 0 to 47 inches (119 cm) of FR4 trace at 3Gb/s. The
selection of the amount of output de-emphasis is made using the corresponding
OUTPUT_DEEMPHASIS[287:0], MON0_OUTPUT_DEEMPHASIS or
MON1_OUTPUT_DEEMPHASIS bits, shown in Table 4-3.
GX3146 146 x 146 3.5Gb/s Crosspoint
Final Data Sheet Rev. 2
GENDOC-056075 March 2013
www.semtech.com
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