Ds320Pr410 Rx Detect State Machine; Ds320Pr410 Dc Gain Control; Table 2-5. Receiver Detect State Machine Settings; Table 2-6. Gain Control - Texas Instruments DS320PR410-RSC-EVM User Manual

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2.5 DS320PR410 RX Detect State Machine

Each DS320PR410 deploys an RX Detect state machine that governs the RX detection cycle as defined in the
PCI Express specification. At power up or after a manually triggered event, the redriver determines whether
or not a valid PCI Express termination is present at the far end of the link. When the DS320PR410 is in Pin
Mode (MODE = L0), the RX_DET pin of DS320PR410 provides additional flexibility to system designers to
appropriately set the device in their desired mode, according to
PD PIN LEVEL
L
L
L
L
L
H
The RX Detect state of each channel of each device can also be set by writing to SMBus / I
Secondary or Primary Modes. Refer to the

2.6 DS320PR410 DC Gain Control

When operating in Pin Mode (MODE = L0), the GAIN pin can be used to set the overall data-path flat gain (DC
and AC) of the DS320PR410 for channels 0-3 as shown in
The DC gain of each channel of each device can also be set by writing to SMBus / I
Primary Modes. Refer to the
SNLU334 – DECEMBER 2023
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Table 2-5. Receiver Detect State Machine Settings

DS320PR410 Channel
RX_DET PIN LEVEL RX Common-mode
L0
Pre Detect: Hi-Z
L1
Post Detect: 50 Ω
Pre Detect: Hi-Z
L2
Post Detect: 50 Ω
L3
Pre Detect: Hi-Z
L4 (Float)
Post Detect: 50 Ω
X
DS320PR410 Programming Guide

Table 2-6. GAIN Control

GAIN/SDA PIN
LEVEL
L0
L1
L2
L3
L4 (Float) 0 dB (+0.6dB actual - recommended for most
DS320PR410 Programming Guide
Copyright © 2023 Texas Instruments Incorporated
Table 2-5.
Impedance
PCI Express RX detection state machine is disabled.
Always 50 Ω
Recommended for non-PCI Express use cases.
Outputs poll until 3 consecutive valid detections.
Outputs poll until 2 consecutive valid detections.
N/A
TX polls approx. every 150 μs until valid termination
is detected. Rx CM impedance held at Hi-Z until
detection. Reset by asserting PD high for 200 μs then
Hi-Z Reset all DS320PR410 channels signal path and set
Table 2-6.
GAIN SETTING
–6 dB (-5.6dB actual)
–4 dB (-3.8dB actual)
-2 dB (-1.2dB actual)
+2 dB (+2.6dB actual)
use cases)
for details.
DS320PR410-RSC-EVM Evaluation Module
DESCRIPTION
Reserved
low.
their Rx impedance state to Hi-Z.
2
C registers in
for details.
2
C registers in Secondary or
Hardware
7