GS6150 Datasheet, PDF (26/64 Pages) Gennum Corporation – Automatic or Manual Rate Selection

The default de-emphasis settings for each rate are given in the register descriptions for
DRIVER_CONTROL_REG_1 and DRIVER_CONTROL_REG_2 in Table 5-1. De-emphasis is
disabled on both outputs in Bypass mode, when the output is muted, or when the
device is not locked.
4.5.5 Output Common Mode Voltage
The output common mode voltage level (V_CMOUT) is a function of the output voltage
swing, the output driver supply voltage (V_{CC_DDO}) and how the transmission line is
terminated. If the outputs are terminated through 50Ω resistors to a voltage V_TERM
equal to V_{CC_DDO}, as shown in Figure 4-5 below, the output common mode voltage is
given by the following expression:
VCMOUT
=
VCC_DDO
–
Δ_-----V_{---D----D-----O--}
4
If the differential outputs are terminated across a 100Ω resistor, as shown in Figure 4-4
below, the output common mode voltage is given by the following expression:
VCMOUT
=
VCC_DDO
–
Δ_-----V_{---D----D-----O--}
2
Equation 4-2
Equation 4-3
GS6150 _{VCC_DDO}
GS6150 _{VCC_DDO}
50Ω
50Ω
DDO
50Ω
DDO
50Ω
100Ω
V V _{TERM TERM}
50Ω
50Ω
50Ω 50Ω
DDO
50Ω
DDO
50Ω
Figure 4-4: 100Ω Parallel Output Termination
Figure 4-5: 50Ω Termination to V_TERM
4.6 Output Mute, Disable, and Data Selection
The GS6150 outputs can each be individually muted using the DDO0_MUTE and
DDO1_MUTE bits in the DRIVER_CONTROL_REG_0 register at address 19_h.
Each output can also be independently disabled through either register or GPIO control.
When disabled each pin of the output is pulled to V_{CC_DDO}. Register
DRIVER_CONTROL_REG_0 contains both register based disable bits (DDO0_DISABLE,
DDO1_DISABLE) and bits for selection between register and GPIO control
(DDO0_DISABLE_SELECT, DDO1_DISABLE_SELECT). For GPIO control refer to
Section 4.10.
GS6150
Final Data Sheet
PDS-060127
Rev.2
March 2015
www.semtech.com
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