GS6150 Datasheet, PDF (24/64 Pages) Gennum Corporation – Automatic or Manual Rate Selection

4.5 Serial Data Output
The GS6150 has two current-mode differential output drivers, each capable of driving
up to 1V_pp differential into an external 100Ω differential load.
The output drivers operate with any binary coded signal with supported data rates up
to 5.94Gb/s. This is applicable to both the serial data (DDO, DDO) and serial data (DDO1,
DDO1) outputs of the device.
4.5.1 Output Impedance
Each of the GS6150’s output buffers include two on-chip, 50Ω termination resistors.
4.5.2 Output Signal Interface Levels
The serial digital outputs operate within specification with an output CML power supply
of 1.2V to 2.5V.
4.5.3 Adjustable Output Swing
Through the GSPI, the output swing can be set in the range from approximately
230mV_ppd to 930mV_ppd in 45mV_ppd increments, when the outputs are terminated with
50Ω loads. For the exact values, please see Table 4-3 below.
The output swing for each data rate is controlled using the bits in the
DRIVER_CONTROL_REG_3, DRIVER_CONTROL_REG_4, DRIVER_CONTROL_REG_5, and
DRIVER_CONTROL_REG_6 registers at addresses 1C_h through 1F_h.
The device automatically adjusts the swing setting depending on the state of the device
(i.e. detected rate, bypass mode, or mute). There are separate register controls for mute,
bypass and each data rate.
Table 4-3: Serial Digital Output Swing Settings
Register Setting
(See Note 1)
Min
Typ
Max
0000_b
175
230
290
0001_b
205
275
345
0010_b
245
325
405
0011_b (default)
280
370
460
0100_b
310
410
510
0101_b
345
460
575
0110_b
380
510
640
0111_b
420
560
700
Units
mV
mV
mV
mV
mV
mV
mV
mV
GS6150
Final Data Sheet
PDS-060127
Rev.2
March 2015
www.semtech.com
24 of 64
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