• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 15 subscribers
  • Views 540 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

SN6505B-Q1: Thermal issue for SN6505B-Q1

Songzhen Guo
Intellectual 2770 points
Part Number: SN6505B-Q1
Other Parts Discussed in Thread: SN6501-Q1

Hi Expert，

When customer using SN6505B-Q1 for traction inverter.But they meet a thermal issue. Here is the schematic:

At fist, customer follow the reference design of SN6501-Q1; The output current is 10 mA. Customer need this device need work well under 105C environment.

Due to the efficiency difference, we change SN6501-Q1 to SN6505B-Q1;

(Note: TPS76350-Q1 can't work well at 105C, we also change to TPS7B6950-Q1);

When we put the board in to 105C environment for 30 minutes, it can work well. But when the test time extend to 120 minutes, the diode temperature ramp up to 130C. Then SN6050B-Q1 enter to over current protection. When we change the diode to 1N4148 (MBR0402L was used in this board before). It can work well.

Could you analyze it for us? Could you recommend several diode to us?

This is a urgent case for customer. I appreciate it if you can help.

Best Regards

Songzhen Guo

  • 0
    TI__Genius 17100 points

    Hi Songzhen,

    Thank you for posting this on E2E! At temperatures above +85dC, many Schottky diodes have increased Reverse Leakage current (I_R) characteristics, and that higher leakage current causes the push-pull power supply to collapse.

    Although we recommend MBR0520L for typical, high efficiency cases, for high-temperature operation we do recommend RB168MM-40 diodes. A comparison of typical Schottky and low-I_R Schottky diodes can be found on this E2E FAQ for a similar concern from a different customer:



    Please let me know if replacing the diodes to a low reverse-leakage current (I_R) diode, like RB168MM-40, resolves the over-current protection operation and allows both TPS76350-Q1 and TPS7B6950-Q1 LDOs to work in this system.


    Thank you,
    Manuel Chavez

  • 0 in reply to Manuel Chavez
    TI__Intellectual 2770 points

    Hi Manuel,

    Thank you so much for you suggestion. I forward this to customer.

    For the diode recommendation, RB168MM-40 is not a automotive device. Could you recommend a automotive device? Thanks.

    Best Regards

    Songzhen Guo

  • 0 in reply to Songzhen Guo
    TI__Genius 17100 points

    Hi Songzhen,

    You're welcome! Please keep us updated on the result. RB168MM-40TF is the automotive part number for this diode.


    Thank you for your time,
    Manuel Chavez