DS64BR401: About "Idle" of DS64BR401

Hi Shuichi-san,

The TXIDLEA/B pins are used to control channel output behavior.

• 0: Channel output is always active, regardless of the amplitude seen at the channel input.
• 1: Channel output is always muted, regardless of the amplitude seen at the channel input.
• Float: Channel output is dependent on channel input amplitude and idle detect threshold set by the SD_TH pin. If the channel input amplitude is higher than the idle detect threshold, then channel output is active. If channel input amplitude is lower than the idle detect threshold, then channel output is muted.

The SD_TH pin is used to adjust the idle detect threshold. Table 7 and Figure 6 in the datasheet explain how to configure this pin. Note that values given in the datasheet are typical, and there is an assert/de-assert hysteresis of the idle detect threshold.

The RATE pin is used to control the pulse width of de-emphasis of the output.

• 0: Optimizes de-emphasis pulse width for data transmission in the range 2.5 to 3.2 Gbps.
• 1: Optimizes de-emphasis pulse width for data transmission in the range 5.0 to 6.4 Gbps.
• Float: Data rate is detected at the channel input and de-emphasis pulse width is adjusted accordingly.

Additionally, TXIDLEA/B, SD_TH, and RATE pin settings can be overridden with register settings if you are using SMBus mode.

Best,

Lucas

Hi Lucas,

Thank you for replying. I understad your explanations.

I have one more question.
Is the definition of an IDLE a setting for pin strap?
In that case, an IDLE state doesn't exist when using SMBUS, right?

Regards,
Shuichi Sugi