profile match with wide range of channel media characteristics. The EQ profile control feature is only available in

SMBus/I2C mode. In Pin mode the settings are optimized for FR4 traces.

Table 6-1 provides available equalization boost at 20Gbps (10GHz Nyquist frequency) through EQ control pins

or SMBus/I2C registers. In Pin Control mode EQ1 and EQ0 pins set equalization boost for channels 0-3. In I2C

mode individual channels can be independently programmed for EQ boost.

Table 6-1. Equalization Control Settings

EQUALIZATION SETTING

TYPICAL EQ BOOST (dB)

Pin mode

SMBus/I2C Mode

0

L0

L0

0

0

0

1

5.0

1

L0

L1

1

0

0

1

7.0

2

L0

L2

3

0

0

1

8.0

5

L1

L0

0

0

1

0

10.0

6

L1

L1

1

0

1

0

10.5

7

L1

L2

2

0

1

0

11.5

8

L1

L3

3

0

3

0

12.0

9

L1

L4

4

0

3

0

13.0

10

L2

L0

5

1

7

0

13.5

11

L2

L1

6

1

7

0

14.0

12

L2

L2

8

1

7

0

15.5

13

L2

L3

10

1

7

0

16.0

14

L2

L4

10

2

15

0

16.5

15

L3

L0

11

3

15

0

17.5

16

L3

L1

12

4

15

0

18.5

17

L3

L2

13

5

15

0

19.0

18

L3

L3

14

6

15

0

20.0

19

L3

L4

15

7

15

0

20.5

6.3.2 Flat-Gain

The GAIN pin can be used to set the overall data-path flat gain (DC and AC) of the TDP2004-Q1 when the

device is in Pin mode. The pin GAIN sets the flat-gain for channels 0-3. In I2C mode each channel can be

independently set. Table 6-2 provides flat gain control configuration settings. For most systems the default

setting of GAIN = L4 (float) is recommended that provides flat gain of 0dB.

The flat-gain and equalization of the TDP2004-Q1 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.

Table 6-2. Flat Gain Configuration Settings

Pin mode: GAIN

I2C Mode: flat_gain_2:0

Datapath Flat Gain

L0

0

–5.6dB

L1

1

–3.8dB

L2

3

–1.3dB

L4 (float)

5

0.6dB (default recommendation)

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TDP2004-Q1

SNLS787 – SEPTEMBER 2025

Copyright © 2025 Texas Instruments Incorporated

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