DS100KR800 Datasheet, PDF (11/33 Pages) Texas Instruments – Ultra Low Power, 8-Channel Repeater for Data-rates up to 10.3 Gbps

Functional Descriptions
The DS100KR800 is a low power media compensation 8
channel repeater optimized for 10G–KR. The DS100KR800
compensates for lossy FR-4 printed circuit board backplanes
and balanced cables. The DS100KR800 operates in 3
modes: Pin Control Mode (ENSMB = 0), SMBus Slave Mode
(ENSMB = 1) and SMBus Master Mode (ENSMB = float) to
load register informations from external EEPROM; please re-
fer to SMBUS Master Mode for additional information.
Pin Control Mode:
When in pin mode (ENSMB = 0) , the repeater is configurable
with external pins. Equalization and de-emphasis can be se-
lected via pin for each side independently. When de-empha-
sis is asserted VOD is automatically adjusted per the De-
Emphasis table below. The receiver electrical idle detect
threshold is also adjustable via the SD_TH pin.
SMBUS Mode:
When in SMBus mode (ENSMB = 1), the VOD (output ampli-
tude), equalization, de-emphasis, and termination disable
features are all programmable on a individual lane basis, in-
stead of grouped by A or B as in the pin mode case. Upon
assertion of ENSMB the MODE, EQx and DEMx functions
revert to register control immediately. The EQx and DEMx
pins are converted to AD0-AD3 SMBus address inputs. The
other external control pins remain active unless their respec-
tive registers are written to and the appropriate override bit is
set, in which case they are ignored until ENSMB is driven low
(pin mode). On power-up and when ENSMB is driven low all
registers are reset to their default state. If RESET is asserted
while ENSMB is high, the registers retain their current state.
Equalization settings accessible via the pin controls were
chosen to meet the needs of most applications. If additional
fine tuning or adjustment is needed, additional equalization
settings can be accessed via the SMBus registers. Each input
has a total of 256 possible equalization settings. The tables
show the 16 setting when the device is in pin mode. When
using SMBus mode, the equalization, VOD and de-Emphasis
levels are set by registers.
The input control pins have been enhanced to have 4 different
levels and provide a wider range of control settings when EN-
SMB=0.
Table 1: 4–Level Control Pin
Settings
Pin Setting Description
Voltage at Pin
0
Tie 1kΩ to GND
0.03 x VDD
R
Tie 20kΩ to GND
1/3 x VDD
Float
Float (leave pin open) 2/3 x VDD
1
Tie 1kΩ to VDD
0.98 x VDD
Note: The above required resistor value is for a single
device. When there are multiple devices connected to the
pull-up / pull-down resistor, the value must scale with the
number of devices. If 4 devices are connected to a single
pull-up or pull-down, the 1kΩ resistor value should be
250Ω. For the 20kΩ to GND, this should also scale to 5kΩ.
3.3V or 2.5V Supply Mode Operation
The DS100KR800 has an optional internal voltage regulator
to provide the 2.5V supply to the device. In 3.3V mode, the
VIN pin = 3.3V is used to supply power to the device and the
VDD pins should be left open. The internal regulator will pro-
vide the 2.5V to the VDD pins of the device and a 0.1 uF cap
is needed at each of 5 VDD pins for power supply de-coupling
(total capacitance should be ≤0.5 uF). The VDD_SEL pin
must be tied to GND to enable the internal regulator. In 2.5V
mode, the VIN pin should be left open and 2.5V supply must
be applied to the VDD pins. The VDD_SEL pin must be left
open (no connect) to disable the internal regulator.
FIGURE 4. 3.3V or 2.5V Supply Connection Diagram
30148006
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