TPS2640: spec check

Hello,

Welcome to E2E.

Please confirm whether you have removed the short on output after the short-circuit. 

Is the eFuse working after power recycle or toggle through SHDN?

Can you capture waveform during short circuit probing VIN,VOUT, IIN and FLT for better debug?

Thanks 

Amrit 

Hi Amrit 

1. After modifying Pin25, PowerPad connected to Net: RTN, the output still did not recover after short circuit.

2. Regarding this issue, the FLT waveform after the power is turned on does not look right.

Hello Garte,

Why FLT is going high? which source is it pulled up to?

Schematic I can't see it.

Can you include Input current waveform? If it's hard short eFuse will latch off. During soft short which means you removed the short right after, eFuse will regulate current to IOL and based on MODE pin it will operate. Check out datasheet 9.3.5.2 Short Circuit Protection for more detail.

Input current waveform is required to know that.

Thanks 

Amrit 

Hi Amrit 

Add input current measurement waveform (CH4: Ain)

Hello Gareth,

How VOUT is coming up after short? Is it going into auto-retry now or you are doing power cycle?

Thanks 

Amrit 

Hi Amrit

The system will automatically retry, but sometimes it will stop, and the FLT Pin waveform is also abnormal

eFuse issue.pdf

Hello Gareth,

auto retry will stop when device hits TSD (Thermal shut down). After hitting TSD device will latch off.

FLT is open drain. During FLT it will assert to GND. From waveform FLT is abnormal before FLT. Is the source noisy where FLT is pulled up?

Thanks

Amrit 

Hi Amrit

FLT's Pull Hi power micro system + V3.3S has no noise

Add a 10k resistor to ground at the output FLT can return to normal

Hello Gareth,

What's the pull up resistance you have used with 3.3V supply?

When the pull-up resistor is adjusted from 10k to 25k or floating, the FLT will be LOW and jump abnormally.

ch1=vin  ch2=vout ch3=FLT 

But as long as the output end is loaded with 10k, it will return to normal

Is there any EVM with no load at the output? What is the waveform of FLT? Is it necessary to add a load at the output?

Hello Gareth,

FLT is not asserted even after device turns on.

I believe the pull up source has some issue. Can you check with strong pull up/

May be higher voltage and 5K pull up resistance.

Thanks

Amrit 

Hi Amrit

If there is no load on the output, do I need to add a resistor?

It's not necessary.

If you add load, Is FLT going up?

Amrit

Yes, Increase the load, and the FLT signal will be normal.

Is there chances of VOUT going higher than VIN?

FLT can be asserted when reverse current is detected.

Can you check VOUT and VIN values?

Hi Amrit

FLT's Pull Hi power supply, I soldered in the eFuse and the output 24V waveform did not improve. I have tried 5K/10K/20K resistors.

Could you help check the below schematic and any need to adjust 

Modify PowerPAD and Gnd separately

Thank you

tps2640 schematic.pdfGPIO.pdf

Hello Gareth,

We can discuss the results online over call and debugs.

I have sent request and will share my mail.

Thanks 

Amrit