TPS22965: Load switch reboot and inrush current issue

Hi Team 

We are waiting for your inputs.

we are holding our testing. Your inputs will be invaluable for our testing.

Regards,

sathya Priya N

Hi Team,

As per your suggestion we tried the following test cases:

We changed Cin 22uF and CT 0.22uF it is still rebooting/crashing.

we changed Cin= 22uf and CT=1000pF, it is stable but same time it is crashed/rebooted less frequently. (eg: in 20 times,3 times crashed)

we need to confirm one thing, in the above circuit whether we need to change only CT ? or we also need to change Cin value?

And, we want to know for Vin= 3.57V, how to calculate the CT value (if depends on rise time how we need to arrive for that? in datasheet we seen, it is given for 3.3V only.

We are using the TPS22965N Load switch for 5G Power supply control (VBAT: 3.56V@4A Peak current)

Two 5G modules we are using, in one 5G module we are facing this issue, whereas other 5G module is  working fine in the above circuit.

Waiting for the response!

Thanks in advance.

Regards,

Sathya Priya N.

Dear Patrick Shalton

We tried CIN = 22uF and COUT = 10uF ,CT=0.01uF our observation 20 time 3 time device is fail. Currently improve but still some time failing.  

Kindly guide for Load switch CIN,COUT,CT value for support inrush current (5G Modem 3.56V@4A Peak current). we  not observed any voltage dip in supply line. 

Waiting for your inputs.

Thanks & Regaeds,

Vishal Mistry

Hi Sathya, Vishal,

Thanks for the updates. One thing I'd like to clarify is - when are you seeing your board reboot? When you are turning the device from OFF to ON? Or during normal operation? I don't quite understand, as I can't see a common scenario for the output be low after the soft start.

My thought was that when the device starts up, perhaps the input voltage droops due to the startup slew rate or it overheats if the downstream components try to pull 4A during soft start, but it seems like at least the first part isn't the case. Are you using a constant current e-load, and is it on during the device's startup time?

If the input voltage was drooping due to the startup slew rate, then adding more input capacitance would mitigate this issue. But since that's not the case, we should isolate the issue to know how to proceed. Can you attach a waveform of when you see this reboot happening so we can see what is causing it?

Are you PWMing the ON pin of the TPS22965? And is there any difference between the two implementations of TPS22965 you referred to, especially in the load?

At VIN = 3.57V, the rise time can be interpolated based on the data at 3.3V and 5V.

Thanks,

Patrick

Dear Patrick,

In our setup, we utilize a 3.5V@8A regulated supply for the SoM board, and a 3.5V@2.5A supply for both the Telit FN990 module and another component. The Telit module requires a peak current of 4A at 3.5V, which we manage with the TPS22965NDSGR load switch for software control.

when are you seeing your board reboot? When you are turning the device from OFF to ON? Or during normal operation?

- Specifically, we observe kernel crashes during soft start, occurring approximately 2 times over 40 consecutive observations, while validating device ON/OFF conditions continues with CIN = 22uF, COUT = 10uF, and CT = 0.01uF.

Are you using a constant current e-load, and is it on during the device's startup time?

- Our load is connected to a 5G modem (FN990).

We'll capture waveforms for further analysis and share them with you soon.

Let me know if you have any query

Thanks & Regards,

Vishal Mistry