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.

TPS2HB16-Q1: Problem with switch disabling at programmed current limit

Part Number: TPS2HB16-Q1

I am using the TPS2HB16AQPWPRQ1 WITH THE HSS-MOTHERBOARDEV. Although I configure the board to disable the switch at a particular current (for example 7 amps or 3 amps) it does not disable until it goes into thermal shut down I have tried everything to get it to work but have been unsuccessful.

The HSS-MOTHERBOARDEV configuration is as follows: Vbb = 12.0 volts, LATCH Enabled, Channel 1 enabled, Channel 2 disabled, CH1 Current selected for SNS, Output DIAG Enabled, R_ILIM is connected between TP17 and Vbb.

To test the current limit feature the following R_ILIM resistors were selected (separate tests): R_ILIM = 14.7 kohms for a current limit of approx 7 amps R_ILIM = 20.0 kohms for a current limit of approx 5.1 amps.

The load used: Hauman Inc. EL-150, Electronic Load Load connected to VOUT1 and GND

Test procedure: The Electronic Load current was increased past the anticipated current limit, first for the 7 amp current limit setup then for the 5.1 amp current limit setup. In both tests the TPS2HB16AQPWPRQ1 device did not disable the the switch. Even when the load current was increased to 12 amps the device did not disable.

  • Hi Edward,

    Welcome to E2E and thanks for reaching out!

    Would you be able to connect the resistor to VBB  from the Ilim pin directly on the daughterboard instead of using the TP17 on the motherboard? Does this occur if you switch it from channel 1 to channel 2?

  • Anthony, thank you for your reply.

    Since it would be difficult to connect VBB directly to the Ilim pin on the daughter board I verified continuity between TP17 and pin 5 on the IC itself (and also verified continuity between TP18 and pin 12 on the IC).

    Yes, it also occurs if I switch from channel 1 to channel 2. (I actually started with channel 2 then switched to channel 1 in an effort to troubleshoot the problem).

    Thanks again,

    Edward Brandel

  • Hi Edward,

    Got a few questions for you to hopefully help narrow down the issue:

    • Can I ask how you are connecting VBB to the resistor? Would you be able to try pulling the resistor up to 5V? 
    • Would you be able to share a waveform of the current at the output and what is seen 
    • Also you mentioned that it goes into thermal shutdown, how long does this take?
  • I discovered the problem.

    With power removed I disconnected the 14.7K R_ILIM resistor and measured the resistance between TP17 AND Vbb. I expected high impedance and instead measured 10K. I then discovered that there are 10K resistors on the bottom side of the daughter board, (R1_S and R2_S for this particular board).

    Somehow I overlooked the description of these current-limiting resistors in the Motherboard data sheet.

    Thank you everyone for your time and effort in helping me solve my problem.

    Edward Brandel