TPS53318: Issue facing with TPS53318

Hi Anmol,

David will check your question and reply you soon.

Anmol,

There are two items that stand out when I review.  

The C1 is 1nF and should be 1uF from the webench simulation I ran.

Also, The C4 is 100nF and should be 1nF.

Hi David<

Thanks for your response.

I am using the same components that you are suggesting and i am getting output voltage 5.1V

when i take 1A current works fine start increasing current by 0.2A it looks like working ok till 3Amp.

but when i take current 2Amp or even 1.5Amp initially when starting the device, output voltage goes to zero instantly.

Or if i change the current from 1A to 2A/3A then even output goes to 0V

I am not able to figure out what can be the issue.

the current limit threshold  could be triggering.

With an oscilloscope, check the output voltage. If the output ramps and stops for 16ms before restarting the current limit is triggering. 

Increase the current limit trip threshold  or increase the soft start time change mode from 100 to 475kOhm to reduce the inrush current at startup. .  

How can i increase current limit trip threshold?

As i increase the current with 0.1Amp step it goes upto 3Amp but votage comes to 4.8V at 3Amp (Output voltage is not stable)

When i start the device at 1Amp load current looks OK and when i start the device at greater than 1Amp, output voltage drops to zero volt.

The resistor on the TRIP pin sets the overcurrent limit.    Change the R8 (60.4kOhm) to greater value to increase the limit. 

The Trip resistor Equation 18 in datasheet https://www.ti.com/lit/ds/symlink/tps53318.pdf#page=25 

Try a 100kOhm resistor 

Can you post an oscilloscope image of the output voltage and the LL node when the output current is 1A and near 3A. 

Hey David,

One thing i observed here is i am not able to go beyond 3.1Amp in any case.

i think when i start the device at 3Amps directly, maybe peak current goes beyond 3Amps that's why device is not starting at 3Amps or 2Amps directly and output voltage comes to zero.

I tried increasing the resistor value at trip like 100k even 340k but there is no change in devikce behaviour. and evne changing the soft start resistor value.

But there is one more thing is that the device supports upto 8Amps so what can be the possible reason, i am not able to understand?

Hi Anmol,

Due to US holiday, Daniel will reply you after 7/4, appreciate your patience.

There are several faults that can cause the output voltage to shutdown,  OCP, OVP, UVP, OTP, UVLO.

We need pin waveforms to identify the issue. 

Post an oscilloscope plot during incident.   Output Voltage, LL node and VREG node.