Table 7-1. Equalization Control Settings

EQUALIZATION SETTING

TYPICAL EQ BOOST (dB)

EQ INDEX

EQ1_0 (Ch 0-3) / EQ1_1 (Ch

4-7)

EQ0_0 (Ch0-3) / EQ0_1 (Ch

4-7)

@ 4 GHz

@ 8 GHz

0

L0

L0

0.0

-0.1

1

L0

L1

1.5

4.5

2

L0

L2

2.0

5.5

3

L0

L3

2.5

6.5

4

L1

L0

2.7

7.0

5

L1

L1

3.0

8.0

6

L1

L2

4.0

9.0

7

L1

L3

5.0

10.0

8

L2

L0

6.0

11.0

9

L2

L1

7.0

12.0

10

L2

L2

7.5

12.5

11

L2

L3

8.0

13.0

12

L3

L0

8.5

14.0

13

L3

L1

9.5

15.0

14

L3

L2

10.0

16.0

15

L3

L3

11.0

17.0

DS160PR412/421 Programming Guide for details.

7.3.2 Flat Gain

The GAIN pin can be used to set the overall datapath flat gain (broadbabd gain including high frequency) of the

DS160PR412 when the device is in Pin Mode. The default recommendation for most systems will be GAIN = L3

(float).

The flat gain and equalization of the DS160PR412 must be set such that the output signal swing at DC and high

frequency does not exceed the DC and AC linearity ranges of the devices, respectively.

Note the device also provides AC (high frequency) gain in the form of equalization controlled by EQ pins or

7.3.3 Receiver Detect State Machine

The DS160PR412 deploys an RX detect state machine that governs the RX detection cycle as defined in the

PCI express specifications. At device power up or through manually triggered event using PD or SEL pin or

termination is present at the far end of the link. The RX_DET pin of DS160PR412 provides additional flexibility

for system designers to appropriately set the device in desired mode according to Table 7-2. For the PCIe

application the RX_DET pin can be left floating for default settings.

Note power up ramp or PD/SEL event triggers RX detect for all four channels. In applications where

DS160PR412 channels are used for multiple PCIe links, the RX detect function can be performed for individual

Table 7-2. Receiver Detect State Machine Settings

PD

RX_DET

RX Common-mode Impedance

COMMENTS

L

L0

Always 50 Ω

PCI Express RX detection state machine is disabled.

Recommended for non PCIe interface use case where the

DS160PR412 is used as buffer with equalization.

www.ti.com

DS160PR412

SNLS685 – DECEMBER 2020

Copyright © 2020 Texas Instruments Incorporated

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