TPS5430: Short Circuit Protection

Hi Nimit

TPS5430 has in-built short circuit protection. It has both cycle by cycle and hiccup mode to avoid damage during short circuit events. 

Typical current limit for this device is around 5A

For more details you can refer - 6.3.9 Overcurrent Limiting  

Thank you

Regards

Onkar Bhakare

I have LM2596 circuit tooo. Whenever lm2596's output is short to GND it auto shuts down, where as in TPS5430 it is not the case. I tried shorting TPS5430 output to ground that resulted in damaged output inductor. Any idea of the cause as same thing in working for LM2596. If you need my schematic then do let me know i can post it.

Thanks.

For one more update i have left ENA floating and when output is shorted the voltage is vin goes till 5 to 8 Volts.

Yes Nimit, Kindly share your schematic. Additionally, could you please try progressively overloading the device upto current limit? 

Thank you

Regards

Onkar Bhakare

Greetings,

Below is the schematic. Input voltage is 14VDc or 13.98 VDc. Value of inductor is 47uH and current capacity is 1.2 A. Voltage divider resistors value is R3 = 10K and R4=3.24K and output capacitor is 100Uf 25V or 150Uf 25V. On output side i have used zener diode of 5.1V. Input capacitor is 22uF and 50V and catch diode is ss34.

Let me know if any problem with the schematic. I am also uploading pcb and let me tell you i am no expert in pcb design so there are faults in it. Let me know the corrections.

Hi Nimit

I revived your schematic and layout; it looks fine to me. Except, inductor value is quite large you can reduce it to 18 or 22 uH.

Now coming backt to issue: This device implements hiccup mode to prevent current runaway. This protection mode triggers when 2 consecutive current limit cycles occur with minimum on time. To debug the issue, let's see if hiccup mode is triggering properly. Could please share SW, IL, Vout waveforms by shorting the output? Output can be shorted for very small duration to protect the inductor.

Thank you

Regards

Onkar Bhakare

Greetings Onkar,

Well i do have scope but i am not an expert in using this device. I hope you have an idea what i want. I want TPS5430 to auto shutdown in case of output shorted to ground.

Hi Nimit

It would be bit difficult to debug without waveforms. Could please how are shorting the output? Is it through very low impedance cable?

Regards

Onkar Bhakare

Greetings Onkar,

I am directly connecting 5VDc and Gnd terminals together for moment as high current flow heats up the inductor. Yes low impedance cable.

One thing i have noticed that as the output is shorted the value of Vin does not drop drastically it goes till 10 VDc if i keep it shorted for like 2 secs. or more.

Hi Nimit

Could you please share part no. of inductor. There is possibility of inductor saturation and thus breakdown of inductor. 

Thank you 

Regards

Onkar Bhakare

It's CD54 series inductor with marking 470. Yes chinese manufacturer but works well in other circuits. This inductor breaks down after 5 seconds.

Hi Nimit

Do you have its datasheet or information on saturation current. If Isat is lower than minimum peak current limit it would create issue

Probing the inductor current would help in better understanding of the issue. Could you please share IL waveform? You can run it for few ms to avoid breakdown.

Thank you 

Regards

Onkar Bhakare

ok i can get that image but i need some time.. Got stuck in other work.

Okay Nimit

Let me know once you have those waveforms available.

Thank you

Regards

Onkar Bhakare

Greetings Onkar,

I have another circuit with TPS5430 and it is working perfectly fine. May be in this current design there might be some issue in schematic so its not working as expected. You can close this topic now.