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TLV767EVM-014: Output performance test

Kay Chen53
Expert 2225 points
Part Number: TLV767EVM-014

Hi there:

We're testing the EVM with several condition for our customer.

Vin: 15V, Vout: 12V/1A --- OK, eff%= 79%

Vin: 15V, Vout 5V --- no output, Is that due to power supply input current limit?

Vin: 15V, Vout 3.3V --- no output, Is that due to power supply input current limit?

Vin: 15V, Vout 1.2V --- no output, Is that due to power supply input current limit?

Vin: 5V, Vout 3.3V/1A ---OK, eff%= 67%

Vinr: 5V, Vout 1.2V --- no output,  Is that due to power supply input current limit?

  • 0
    TI__Mastermind 44790 points

    Hi Kay,

    How are you measuring the output voltage? Is this with a multi-meter or with an oscilloscope? The reason I am asking is a multi-meter will tend to average the output so it may appear as though there is no output when the device is in thermal shutdown. Thermal shutdown is likely when looking at dropping 15V down to 5V as the power dissipated is (VIN-VOUT)*ILOAD. So even when 100mA of load current and 5V at the output this is 1W of power dissipation. I

    A simple way to look at LDO efficiency is 100*VOUT/VIN.

    With respect to the input current limit, the device at startup has two protection features:

    #1. Inrush control into the load or soft start. It tries to slowly ramp the current into VOUT to minimize th droop on VIN.

    #2. Fold-back current limit limits the current into the load to only ~250mA until the voltage at the output starts to rise. As the output voltage rises, more current is allowed into the load.

    Because of these two protection schemes, if you are tested with an electronic load, it may appear as the device is not powering up. If you switch to a resistive load, you will likely see different behavior,

    Can you confirm your test setup?

  • 0 in reply to JCHK
    TI__Mastermind 23361 points

    Hi Kay,

    This is no update on this thread for more than 10 days. I am closing it now assuming the issue has been resolved. If this is not the case, please simply post your new reply.

    Regard,
    Jason