TPS55288: MOSFET SOA

Hi Jeff,

Thanks for reaching out.

We don't have the SOA curve like discrete MOSFET. May I know what concern does the customer have now?

BRs,

Bryce

Hi Bryce,

We just adjust OCP_DELAY to 3ms. We found peak current may up to 30A. just wants double check if may cause TPS55288 damaged.

Do you have any idea for this?

Thanks!

Jeff

(Above waveform is output short to GND test)

Hi Jeff,

Thanks for the background, may I know if the current is the inductor current?

What is the input voltage and the output current when do the Vout short to GND test?

And how does the customer do the short test? Use a air-switch or e-load? 

Does the customer test on TI EVM? Because I saw the current uses about 500us to rise to 30A. Can the customer also probe SW1 and SW2 waveforms when doing the test?

BRs,

Bryce

Hi Bryce,

1. may I know if the current is the inductor current? 

=> output current

2. What is the input voltage and the output current when do the Vout short to GND test?

=> input voltage= 20V, output current = as previous waveform.

3.And how does the customer do the short test? Use a air-switch or e-load? 

=> e-load

4. Does the customer test on TI EVM? Because I saw the current uses about 500us to rise to 30A. Can the customer also probe SW1 and SW2 waveforms when doing the test?

=> On customer own board. For SW1/SW2 as below.

Thanks!

Jeff

Hi Jeff,

I will do the test with TI EVM on lab together, it is strange that when PD voltage is zero but SW2 still remains 4V, is there is a long wire between Vout and PD? Can you share the schematic and layout for the customer's board?

BRs,

Bryce

Hi Jeff,

Below is the test result of Vout short to GND on TI EVM, you can see that the max output current is clamped to about 16A which is the average inductor current value.

BRs,

Bryce

Hi Bryce,

Update SW1/SW2 waveform. Previous waveform load wire is long, some may cause voltage abnormal. thanks!

Hi Jeff,

Can you also share the schematic and layout screenshot?

And can you help probe the inductor current when the output current rises to 30A? 

Can you also zoom in the waveform including SW1, SW2, iL, Vout when PD=0 but SW2 is switching? That is strange that PD=0 but SW2 still equals to 20V. Which test point does thecustomer probe at? Can you take a photo and show the test point?

BRs,

Bryce

Hi Bryce,

Here is set up figure and inductor waveform, due to we just have 1 current probe, so only provide iL. thanks!

Thanks!

Hi Jeff,

The inductor current is well limited at about 16A as the schematic ILIM set, what about changing another e-load and do the test again?

And I think the customer doesn't need that high. May I know what is the customer and the output power here?

Also, does the customer disable the output current limit function of TPS55288? Because the output current is high.

BRs,

Bryce

Hi Bryce,

Got it, and one more question.

The "OCP Delay" section has three time settings: 3ms, 6ms, and 12ms. I would like to inquire whether, during these time intervals of 3ms, 6ms, and 12ms, there is a specified threshold for the current peak that must be exceeded to trigger Overcurrent Protection (OCP). Alternatively, does OCP remain inactive within these timeframes, regardless of the magnitude of the current peak?

Thanks!

Jeff