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Original question:

TPS2359: Set 3.3 V rail output current limit to 250mA

TPS2359: ORing MOS can not be opened

Jeff Xie
Intellectual 1780 points
Part Number: TPS2359

Hi all,

When TPS2359 12V channel is enabled, BLKA output voltage is about 12V, and ORing MOS can not be opened.

See figure below. Channel 2  are BLKA voltage and channel 3 are PASSA voltage.

  • 0
    TI__Guru 57737 points

    Hi Jeff,

    I will look into this and will get back to you end of today.

  • 0 in reply to Praveen GD
    TI__Guru 57737 points

    HI Jeff,

    We expect the voltage at BLKA pin to be 23V and 0V during ON and OFF conditions respectively. Can you please 

    • What is the input voltage when the measurement is taken ?
    • Do you see the same behavior in the 12B channel as well ?
    • Did you try replacing the IC and doing the same test ? Do you see the same result ? 

    Can you let me know why the BIt 6 of Register 0 is set. This will increase the ORing turn off threshold to +3 mV. This means if the load cannot maintain the required positive voltage drop across the combined resistance of the external FETs and the sense resistor, the ORing FET is pulled Low.

    • What is the load current when you have taken the measurement ? 

  • 0 in reply to Praveen GD
    TI__Intellectual 1780 points

    Hi Praveen,

    Please see customer's feedback below.

    1. Input voltage -- 11.5V~12.2V

    2. Is there a problem with channel A and channel B? Is there a correlation between the two?

    At present, there is no correlation.

    3. Please try to replace the chip and repeat the experiment - - will verify after new replacement.

    4. Why is Bit 6 of Register 0 1? Is there any special reason? Setting according to the description of data sheet;

    5. Load Current - Load Current 13A

  • 0 in reply to Jeff Xie
    TI__Guru 57737 points

    Hi Jeff,

    Thanks for sharing the requested details. I don't see any issue with the operating conditions. 

    The two channels work independently and you should see BLKA and BLKB around 23V when powered ON. 

    Before replacing the IC can you replace the ORing FET to rule out possibility of the ORing FET getting damaged.