This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TUSB501-Q1: short to battery

Part Number: TUSB501-Q1

Tool/software:

Hi BU team 

My customer has below concern on the solution in below link on tusb501-Q1 short-to-battery protection. Would you help share your comments?

(+) TUSB501-Q1: short to battery - Interface forum - Interface - TI E2E support forums

1.  Under which condition  a 1 or 2 ohm resistor between the ESD diode and the device are needed to protect the 501 from incoming current, ESD or shott-to-battery?

2. what is the suggested package size for this small resistor?

  Shane Hauser said

You would also need a 1 or 2 ohm resistor between the ESD diode and the device to protect the 501 from incoming current. Note that this resistance may slightly affect your signal integrity. 

 

In Rx side, why is AC coupling capacitors 330nF instead of 100nF? 

If no available higher 16V rated voltage for 0402 cap package, is the cap with 220nF /16V/0402 ok ? Here the maximum battery is 16V. 

Thanks 

  • Hi Ted,

    Under which condition  a 1 or 2 ohm resistor between the ESD diode and the device are needed to protect the 501 from incoming current, ESD or shott-to-battery?

    The 1 to 2 ohm resistor to add additional impedance on the signal path in an ESD event. This resistor will reduce the current passed through to the TUSB501-Q1. This resistor will not help much in the event of a short to battery. 

    2. what is the suggested package size for this small resistor?

    The suggested package size 0201.

    In Rx side, why is AC coupling capacitors 330nF instead of 100nF? 

    On the signal path the series capacitance of the USB lines must be between 75nF and 265nF. This capacitance value must be a combination of the TX and RX capacitors. If you are planning to use a 100nF capacitor on the TX side and 100nF on the RX side the combined capacitance will be 50nF which is below the spec requirements. The 330 nF will allow you to use 100nF on the TX side and be over 75nF as the minimum series capacitance. 

    If no available higher 16V rated voltage for 0402 cap package, is the cap with 220nF /16V/0402 ok ? Here the maximum battery is 16V.

    Yes its best to use a capacitor with a rating 16V or higher. 

  • HI Vishesh

    Got it. It is very clear.

    Thanks very much. 

  • Hi Vishesh

    What's the potential risks if  customers don't place the 1 or 2 ohm resistor between the ESD diode and the device in an ESD event?

    For there is not the 0201 package in their BOM system, is it ok that this resistor is replaced with the 0403 package?

    Thanks 

  • Hi Ted,

    The series resistor will limit any current that escapes onto the device. I recommend keeping the  1-2 ohm resistor, and replacing it with a 0 ohm if there is high ESD confidence. Having an 0403 package on the high speed lines will result in more reflections due to the large size of the part with respect to the trace width. For best performance keep the 0201 package.