DS80PCI810 Datasheet, PDF (42/60 Pages) Texas Instruments – Low-Power 8 Gbps 8-Channel Linear Repeater

DS80PCI810
SNLS493A – OCTOBER 2014 – REVISED JANUARY 2015
www.ti.com
The SMBus Slave Mode code example in Table 12 may be used to program the DS80PCI810 with the
recommended device settings.
REGISTER
0x06
0x0F
0x10
0x11
0x16
0x17
0x18
0x1D
0x1E
0x1F
0x24
0x25
0x26
0x2C
0x2D
0x2E
0x33
0x34
0x35
0x3A
0x3B
0x3C
0x41
0x42
0x43
WRITE VALUE
0x18
0x03
0xAE
0x00
0x03
0xAE
0x00
0x03
0xAE
0x00
0x03
0xAE
0x00
0x03
0xAE
0x00
0x03
0xAE
0x00
0x03
0xAE
0x00
0x03
0xAE
0x00
Table 12. SMBus Example Sequence
COMMENTS
Set SMBus Slave Mode Register Enable.
Set CHB_0 EQ to 0x03.
Set CHB_0 VOD to 110'b.
Set CHB_0 VOD_DB to 000'b.
Set CHB_1 EQ to 0x03.
Set CHB_1 VOD to 110'b.
Set CHB_1 VOD_DB to 000'b.
Set CHB_2 EQ to 0x03.
Set CHB_2 VOD to 110'b.
Set CHB_2 VOD_DB to 000'b.
Set CHB_3 EQ to 0x03.
Set CHB_3 VOD to 110'b.
Set CHB_3 VOD_DB to 000'b.
Set CHA_0 EQ to 0x03.
Set CHA_0 VOD to 110'b.
Set CHA_0 VOD_DB to 000'b.
Set CHA_1 EQ to 0x03.
Set CHA_1 VOD to 110'b.
Set CHA_1 VOD_DB to 000'b.
Set CHA_2 EQ to 0x03.
Set CHA_2 VOD to 110'b.
Set CHA_2 VOD_DB to 000'b.
Set CHA_3 EQ to 0x03.
Set CHA_3 VOD to 110'b.
Set CHA_3 VOD_DB to 000'b.
8.1.3 Rx Detect Functionality in PCIe Applications
In PCIe systems, specifications require the Tx to implement Rx detection in order to determine whether an Rx
endpoint is present. Since the DS80PCI810 is designed for placement between an ASIC Tx and endpoint Rx, the
DS80PCI810 implements automatic polling for valid Rx detection when the RXDET pin is left floating or tied low
via 20 kΩ to GND. If 50 Ω impedances are seen on both positive and negative outputs of a DS80PCI810
channel, the Rx detect state machine asserts Rx detection, and a 50 Ω termination to VDD is provided at the
respective channel's positive and negative input. For open PCIe systems where users may swap multiple cards
in and out of a given PCIe slot, it is recommended to keep the RXDET pin floating. For closed systems where an
endpoint Rx is present in a PCIe slot at all times, the RXDET pin may be left floating or tied high via 1 kΩ to VDD
(2.5 V mode) or VIN (3.3 V mode).
For more details about DS80PCI810 Rx detection, refer to Table 2.
8.2 Typical Applications
8.2.1 Generic High Speed Repeater
The DS80PCI810 extends PCB and cable reach in multiple applications by using active linear equalization. The
high linearity of this device aids specifically in protocols requiring link training and can be used in line cards,
backplanes, and motherboards, thereby improving margin and overall eye performance. The capability of the
repeater can be explored across a range of data rates and ASIC-to-link-partner signaling, as shown in the
following two test setup connections.
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