LM5069: False trip due to load transients

Hi Gaurav,

If you use adequate output capacitance to support transient load, the Vin should stay stable and avoid false UVLO trips.

Can you share load requirements.

BR, Rakesh

Hi Rakesh,

The 50V Vin feeds a regulator with an output of 30V output at 6A load requirement. We have a capacitance of around 50uF polytantalum at regulator output.

Regards

Gaurav

Hi Gaurav,

Can you share block diagram of your system.

BR, Rakesh

Book1.pdfPFA Rakesh,

Regards

Gaurav

Hi,

What solution is being used for UVLO, OVP, REVERSE POLARITY PROTECTION now ? Can you share test waveform of  input voltage, output voltage and input current of the first block at the instant of false trip.

BR, Rakesh

Hi Gaurav,

Any updates ?

BR, Rakesh

Hi Rakesh,

We use the LT part LTC4367 as of now. But since it doesnt have any fault timer feature, there are frequent trips. Its difficult for me to share the waveforms right now.

Meanwhile, is it possible to use LM5069 for this application so that we can de-glitch and reject a nuisance fault using the timer feature? What we need is that the fault be considered only if it exists for a minimum defined period instead of any glitch or transient.

Regards

Gaurav

In continuation to last message, please note the nuisance trips happen due to the undervoltage threshold violations caused by transients on load current draw.

Regards

Gaurav

Hi Gaurav,

Have you tried placing capacitor at UV pin of the device to provide delay for the Vin transients ? Can you share full schematic and few test waveforms when ever possible.

BR, Rakesh

Rakesh, we will check. Meanwhile pls respond to my query if the fault timer feature can be used to set a de-glitch time for UV fault detection in LM5069 or any other TI device.

Regards

Gaurav

Hi Gaurav,

Fault timer feature blanks the over current event but not UV fault. We don't have devices with programmable de-glitch time, usually we handle with external RC at the UV pin.

BR, Rakesh