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TPS1H000-Q1: The output current is always limited to unexpected current

Hale Tan
Expert 3770 points
Part Number: TPS1H000-Q1


Hi team,

Please help to answer the following questions about the TPS4H000-Q1 chip:
1. What is the output capacity of each channel independently?
2. We set 4 channels to output a current of about 500mA at the same time, and the total output current of the chip will be clamped at about 1.3A;
3. The two channels are set to output 700mA at the same time, the chip is clamped to 500mA output, and the output will enter the thermal protection mode after a period of time;

The output current is always limited to unexpected current. Could you help solve this issue?
  • 0
    TI__Genius 16145 points

    Hi Hale, 

    To clarify, it sounds like the output load is pulling a smaller current than expected and the device is triggering thermal shutdown? 

    Do you happen to be using an e-load in this test? If so, are you using an e-load in CC or CR mode? 

    The reason we would expect different test results between a true resistive load and an electronic load, is that an e-load in constant current mode will modulate its impedance, and as such the voltage seen at the output of the TPS1H000-Q1 device, to pull a constant current.
    This means a constant current will flow through the device even during turn-on which will result in non-ideal behavior and/or thermal shutdown as significant power is dissipated across the FET. Since the rise time is not immediate, it’s likely that, while the device turned on/increased VOUT, the electronic load pulled its impedance low to draw current from the device. This likely drew more current than intended during startup (while the FET is not at its minimum resistance) which greatly increased temperature. This test if using an eload would not reflect real world usage.

    If you are using a true resistor load for this test, another culprit could be your current limit setting triggering the current limit. Please share a schematic including the CL resistor used so we can determine if this is the case. 

    To answer your first question, we recommend a max output current of 750mA per channel. 

    Best Regards, 

    Elizabeth