TPS1663: TPS16630 short Circuit

Hello Anoop,

Welcome to E2E.

Can you help with waveforms ?

Please get VIN, VOUT, FLT and IIN if possible.

What's the inrush current and load during start-up?

Thanks 

Amrit 

 Hi Amrit

Thanks for the reply.

We don't have waveforms because this is an 8-channel system, making it difficult to determine which channel is causing the issue, especially since the problem does not always occur.

The sequence is as follows:

1. The 48V e-fuse is enabled for all 8 drain channels.
2. After that, the gate voltage is set.
3. Only then is RF power enabled.

Additionally, the drain pin is connected to two 470µF capacitors.

Inrush current  400mA 

Thanks,

Anoop

Hello Anoop,

Is there negative voltage induced on the device?

Can you send me your GaN RF schematic which is connected to TPS2663 output?

If you want, we can have this discussion online and further debug step.

Thanks 

Amrit 

Hi Amrit,

Is there negative voltage induced on the device? ->I haven't tested it

The GaN connected to the eFuse is the GTRB384608FC

We shorted the eFuse output with a 4A resistive load during testing, and it successfully provided protection.

Hi Amrit,

Is there negative voltage induced on the device? ->I haven't tested it,but I will check

The GaN connected to the eFuse is the GTRB384608FC

We shorted the eFuse output with a 4A resistive load during testing, and it successfully provided protection.

Hello Anoop,

Thanks for sharing the block diagram.

Can you help me understand the test case in detail. Do you start-up issue? How do you come to conclusion that eFuse is damaged?

During short circuit test, GaN FET is OFF or ON? or is it in transition?

Do you use negative voltage to turn off the GaN FET?

Thanks

Amrit 

Hello Amrit,

Do you start-up issue, 

How do you come to the conclusion that eFuse is damaged?:- >EFuse input and output showing low resistance, Discreet part all are fine

During the short circuit test, GaN FET is OFF or ON? or is it in transition? ->We test with Resistive load. GaN is not used.

Do you use negative voltage to turn off the GaN FET?-> GaN pinch of voltage is  -ve 6V

Thanks,

Anoop

Hello Anoop,

It would be easy to investigate with wave forms.

Please check if you can capture waveforms as mentioned previously. 

About the down stream load, you mentioned there are DC-DC converters.

Are you using power good pin to enable?

What’s the total output cap including down stream caps?

Thanks 

Amrit 

Hellow Amrit,

Please check the captures below

Experimenting with the MAIN PA eFuse: -> Monitored the input voltage along with the input current of the eFuse (Cdvdt= 0.022uF) on DSO.

1) Efuse - ON Gate-> OFF.  (Drain capacitor 660uF)

-> eFuse Input current
 -> eFuse Input voltage
 -> eFuse Output voltage

2) TX ON  (E-fuse ON, GaN ON)
Here the IDQ current is changed for Carrier ( varied +/- 800mA) a) IDQ current changed to -2.80 

3) PA - OFF(Gate off, Efuse Off)

-> eFuse Input voltage
 -> eFuse Output voltage -->>

Short circuit experiment Wtih Resistive load

4)

Monitoring the eFuse I/P and FLT pin of eFuse:

* To check the fluctuations at the eFuse input and the eFuse FLT pin when short circuits at the output side with load 2A.(resistive load)

5)

Monitoring the eFuse I/P and FLT pin of eFuse:

* To check the fluctuations at the eFuse input and the eFuse FLT pin when short circuits at the output side with load 4A.(resistive load)

Thanks,

Anoop

Hello Anoop,

I will analyse these waveforms and get to you by tomorrow EoD.

Thanks 

Amrit 

Hi Amrit,

Any update?

Thanks,

Anoop

Hello Anoop,
Sorry for the delay here.

What's the current level during short circuit? let me know if you have measured.

From FLT pin, it looks like some other fault happened before short circuit as device is not latch off.

Can you include input current and output voltage in same waveform?

On first waveform on inrush current. Do you have load resistance connected during start-up?

It looks like going into thermal regulation.

Thanks 

Amrit 

Hi Amrit,

Can you include input current and output voltage in the same waveform?-

C2 Output Voltage,C1 Input current

On the first waveform on inrush current. Do you have load resistance connected during start-up? , No, Only 660uF capacitive load.

From the FLT pin, it looks like some other fault happened before the short circuit as the device is not latched off.- we don't have

Thanks,

Anoop

Hello Anoop,

Can we have online meeting to discuss?

Let's connect on email to discuss this.

Can you share your mail id?

Hello Amrit,

sorry for delay i sent friend request