• State Resolved
  • Locked Locked
  • Replies 9 replies
  • Subscribers 63 subscribers
  • Views 1248 views
  • Users 0 members are here
Support feedback
Options
Options
Related

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.

TPS2660: 12V, 0.67A latch off not operate

hj kim
Prodigy 65 points
Part Number: TPS2660

We configured the eFuse circuit using the TPS26600.
We used 12V as input power and set the limit current to 0.67.
Mode is set to Latch Off mode, UVset is 10V, OVset is 30V, Cout is 10uF.
However, if you load a load of 780mA, the LED connected to the FLT will light up and the current will flow only 680mA. Latch off will not work.
If input power is changed to 24V, Latch off normally works.
I want to know what is wrong with my setup.

  • 0
    Prodigy 65 points

    Hi team,

    Could someone reply on this?

    Best regards,
    HJ Kim

  • 0 in reply to hj kim
    TI__Expert 8630 points

    Hello Mr. Shota Mago,

    To understand the cause for this behavior, Can you please share the configuration for the MODE pin ? Is it connected to RTN pin or 402k resistor or Open?

    Can you also share the device part number ? TPS26600 or TPS26601 or TPS26602

    Can you share the waveform for VIN, VOUT, FLTb and IMON pin with overload condition (I > 680mA)?

  • 0 in reply to Lokesh Ghulyani
    Prodigy 65 points

    Hello, Lokesh

    Thank you for your Reply.

    My MODE pin is connected to RTN pin using 402k resistor.

    And my device is TPS26600. 

     VIN

     VOUT

     FLTb

     IMON

    If Mode pin is open then operate auto-retry.

    However, using a 402k resistor does not work with latch-off.

    I don't understand this situation. 

    Please reply to me. 

    Thank you.

  • 0 in reply to hj kim
    TI__Expert 8630 points
    Hello,

    It looks there is a difference of 1V between VIN and VOUT (11.2 - 10.2V) and FLTb pin is low. It means that the device has already turned off the internal FETs due to UVLO, OVP or Overload. You can try increasing the input voltage to 13V, so that the device does not go into UVLO.

    it would really help if you could share the schematic for TPS26600 for your design.
    You can either share the schematic on this thread or send it through email (Email : lokeshgh@ti.com).
  • 0 in reply to Lokesh Ghulyani
    Prodigy 65 points

    Hello,

    I think so.

    So I adjusted the UVLO, OVP, and dVdT using "TPS26600 - Design Calculator Rev1p0_MSB_BD_V10".

    I changed R1, R2, R3,C4 the increase or the decrease.

    However, that did not solve the problem either way.

    Input voltage is fixed on 11.1V by system.

  • 0 in reply to hj kim
    TI__Expert 8630 points
    Hello,

    All the component seem to be of correct value as per design calculator except the components on IMON pin. IMON pin should be connected to RTN pin with a resistor. Refer to section 9.3.5.4 on page 24 of datasheet. We recommend connecting only 43.2k resistor (R1608) between IMON and RTN pins and remove R6, C3.

    A 100k resistor is recommended between IMON pin and ADC input for monitoring currents.
  • 0 in reply to Lokesh Ghulyani
    Prodigy 65 points

    Hello Lokesh,

    I tried to change the hardware configuration according to your advice.

    However, the LED connected to the fault is turned on as usual, and the current is limited, but the output voltage is still output.

    I don't understand this behavior, no matter what configuration is wrong.

    Thank you.

  • 0 in reply to hj kim
    TI__Expert 8630 points
    Hello Hiroshi,

    We will look into this on EVM and will get back.
  • 0 in reply to Lokesh Ghulyani
    TI__Expert 8630 points

    Hello,

    We tried this on EVM with schematic that you provided. With 402k resistor on mode pin, the device limits to current to 12/RILIM value and shuts-down if TJ [Junction temperature] > T SD [Tshutdown]. The device will not shut down and latch off unless TJ > TSD . The device continues to limit the output current until TJ > TSD.

    The junction temperature is a function of ambient temperature, power dissipated by device and θJA.

    On the EVM setup, the device shuts down and latches off when power dissipation in device increases beyond ~3.5W at room temperature.

    If fast turn-off with latch is required in case of overload/over-current condition, then TPS26601 device can be used with MODE pin = open.