TDP158 datasheet(28/55 Pages) TI1

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VOD(SS)

VOD(PP)

Reg0Ch[1:0] = 00

VSADJ = 6

NŸ

Reg0Ch[1:0] = 01

VSADJ = 6

NŸ

VOD(SS)

VOD(PP)

Reg0Ch[1:0] = 00

VSADJ = 6

NŸ

Reg0Ch[1:0] = 10

VSADJ = 6

NŸ

TDP158

SLLSEX2 – DECEMBER 2016

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8.3.11 Pre-emphasis

The TDP158 provides Pre-emphasis on the data lanes allowing the output signal pre-conditioning to offset

interconnect losses between the TDP158 outputs and a TMDS receiver. Pre-emphasis is not implemented on the

clock lane unless the TDP158 is in DP Mode and at which time it becomes a data lane. The default value for

Pre-emphasis is 0 dB. There are two methods to implement pre-emphasis, pin strapping or through I2C

programming. When using pin strapping the SDA_CTL/PRE pin controls global pre-emphasis values of 0 dB or

3.5 dB. Through I2C, reg0Ch[1:0] pre-emphasis values are 0 dB, 3.5 dB and 6 dB. The 6 dB value has different

meanings when device is normal operational mode, reg09h[5] = 0, or when the TDP158 has been put into DP-

Mode, reg09h[5] = 1. In normal operation supporting HDMI when selecting 6 dB pre-emphasis the output will be

more on the order of 3 dB pre-emphasis with a 3 dB de-emphasis, see Figure 25. For DP-Mode selecting 6 dB

pre-emphasis the output will be more on the order of 3 dB pre-emphasis with a 3 dB de-emphasis, see

Figure 26. Table 7 shows VOD(SS) typical values based upon VSADJ setting configured by 6 kΩ VSADJ resistor

for both HDMI mode and DP mode. VOD(PP) value will not go above 1 V.

Figure 25. 3.5 dB Pre-emphasis in Normal Operation

Figure 26. 6 dB Pre-emphasis in DP-Mode

TDP158 Datasheet(PDF) 28 Page - Texas Instruments