TPD2E2U06-Q1: Suitable ESD protection device selection for TPS25854-Q1 D+ and D-

Hi Ochi-san,

Typically, we recommend selecting a diode with a clamping voltage around the absolute maximum, and as you have shown, these devices have a higher clamping voltage compared to the abs max of the TPS25854-Q1 device. It is possible that TPD4E02B04-Q1 would be suitable since there is ~1V variation in DC abs max vs AC abs max, but testing in the customer's system would need to be done to verify this, as this may also depend on other components in the system.

It would also be possible to place a resistor downstream from the diode to create a voltage drop to lower the effective voltage that the downstream IC will see. I am not sure if this will be practical to implement, but selecting the appropriate resistor value might allow for either of these devices to properly protect the TPS25854-Q1 device.

Is there any impedance budget to allow for a resistor to be placed? 

Best Regards,

Josh Prushing

Hi Josh, 

Thank you for comment. 

Josh Prushing said:

It would also be possible to place a resistor downstream from the diode to create a voltage drop to lower the effective voltage that the downstream IC will see. I am not sure if this will be practical to implement, but selecting the appropriate resistor value might allow for either of these devices to properly protect the TPS25854-Q1 device.

Is there any impedance budget to allow for a resistor to be placed? 

We are checking impedance budget for TPS25854-Q1 in below E2E. 

 TPS25854-Q1: Is there any impedance budget for DP and DM pin for external ESD protection device? 

Regards,
Ochi

Hi Josh, 

TPS25854-Q1 BU answers below; 

>By "impedance budget", are you referring to the differential impedance variation for USB data lines? The TPS25854-Q1's DP/DM pins are not for USB 2.0 data transmission. It is only for BC1.2 legacy charging, which are not differential and digital signals that require impedance matching.  

>If you are simply helping a customer find the right external ESD protection device for the TPS25854-Q1's DP/DM pins that is suitable for 6V abs max, is the INT-PD team saying that there isn't any other device to recommend?

Josh Prushing said:

It would also be possible to place a resistor downstream from the diode to create a voltage drop to lower the effective voltage that the downstream IC will see. I am not sure if this will be practical to implement, but selecting the appropriate resistor value might allow for either of these devices to properly protect the TPS25854-Q1 device.

(1) Could you check what is recomended proection device for DP and DM?

(2) If you recommend TPD4E02B04-Q1, do you have 1CH and 2CH version of TPD4E02B04-Q1?

Regards,
Ochi

Hi Ochi-san,

Looking at TI's ESD protection portfolio, the clamping values shown in the datasheet are often higher than the 6V abs max that we are trying to protect against. It is worth stating that some of these values are taken at large test conditions (for instance, ESD321 has a 6.3V clamp at IPP of 6A, but at lower currents, this device would possibly clamp below 6V). I am looking to recommend a device that can protect TPS25854 regardless of the expected transient event, but if you have an expected transient that you are wanting to protect against, I can confirm if we have a device that can clamp below 6V for that condition.

Yoshiki Ochi said:

>By "impedance budget", are you referring to the differential impedance variation for USB data lines? The TPS25854-Q1's DP/DM pins are not for USB 2.0 data transmission. It is only for BC1.2 legacy charging, which are not differential and digital signals that require impedance matching.  

I was referring to the total impedance allowed to not impact signal integrity. If there is impedance available to add to the line without impacting the signal, we can add a resistor to step down the clamping voltage to an acceptable value. For now, I will assume this is not an option unless we can confirm otherwise.

Yoshiki Ochi said:

>If you are simply helping a customer find the right external ESD protection device for the TPS25854-Q1's DP/DM pins that is suitable for 6V abs max, is the INT-PD team saying that there isn't any other device to recommend?

As mentioned above, I cannot recommend a device without considering a specific test condition. If you are able to share a specific transient (according to IEC 61000-4-2/5), this can help me provide a device with more confidence.

Please let me know if you have any additional questions.

Best Regards,

Josh Prushing