TPS54338: TPS54338 Damaged (Burned Out)

Ryu Yamashita

Part Number: TPS54338
Other Parts Discussed in Thread: TPS564257, TPS562212, TPS54295

Hi team,

TPS54338 has been damaged (burned out).
We are currently unable to identify the root cause and would appreciate your support.
We will attach the schematic and layout files.

The operating conditions are as follows:

Power input side (AMP0+V)
- Device configuration: AC adapter -> Power MOSFET
- Input voltage: 24 V
- Current limit: The polyswitch limits the current to 1.5 A, but it does not operate against inrush current.
Load side
- Load devices: One each of TPS564257, TPS562212, and TPS54295
- Load voltage: 10 V
- Load current: Steady-state current is 6.9 mA
Output capacitors
- Part numbers for C17 and C19: GRM31CD71H106KE11L
- According to datasheet section 7.2.2.6 "Output Capacitor Selection":
  Substituting the following values into equation (22) results in Cout > 14 uF.
  Considering DC bias, we selected 20 uF.
  - Delta Iout: 3 A
  - Delta Vout_shoot: 0.5 V (5% of Vout)
  - fsw: 1000 kHz
  - SR Delta Iout: 0.8 A/us

Any advice or suggestions regarding potential causes of this failure would be greatly appreciated.

Best Regards,
Ryu.

2 months ago

0 Haseen Reddy Siripi Reddy 2 months ago

TI__Genius 15340 points

Hi Ryu,

We will review and get back on this.

Regards,

Haseen.

0 Vidhi Sharma 2 months ago in reply to Haseen Reddy Siripi Reddy

TI__Intellectual 1720 points

Hi Ryu,

I see in schematic you've mentioned R3, R4, D1, C8 as unpopulated, but in layout I can see those components. Please clarify are they populated or not. Also, if it's unpopulated, how are you enabling the circuit? Is it unpopulated and short, or unpopulated and open?

Regards,

Vidhi

0 Ryu Yamashita 2 months ago in reply to Vidhi Sharma

Genius 4505 points

Hi Vidihi

Everything is currently unmounted, and the EN pin is left open.
Since this device has an internal pull-up, I believe it should start up even in an open state.

Best Regards,
Ryu.

0 Vidhi Sharma 2 months ago in reply to Ryu Yamashita

TI__Intellectual 1720 points

Hi Ryu,

When you say burned out...which pins got damaged?

Also, how many devices are failed?

Please get the data for each pin to ground impedance using handheld multimeter.

Reagrds,

Vidhi

0 Ryu Yamashita 2 months ago in reply to Vidhi Sharma

Genius 4505 points

Hi Vidhi,

I don't know which pin broke.
It broke and burned out while repeatedly turning the power on and off.
This occurred in 3 out of about 30 prototypes I made.
The impedance between the pins and GND is as follows:

pin		success	failed
1	RT/SYNC	0.3	0.2
2	EN	M	58
3	FB	9.5k	6.4k
4	GND	-	-
5/6	VIN	>800k	0.4
7	MODE	180k	1.0
8	SW	45k	0.4
9	PG/SS	M	69

Best Regards,
Ryu.

0 Vidhi Sharma 1 month ago in reply to Ryu Yamashita

TI__Intellectual 1720 points

Hi Ryu,

Kindly share the layout files (.brd or .pcb) to do a layer by layer review.

Regards,

Vidhi

0 Vidhi Sharma 1 month ago in reply to Vidhi Sharma

TI__Intellectual 1720 points

Hi Ryu,

As discussed over the webex call with Yu Sato, please share the following:

The waveforms for Vin near R3 with AC adapter power on and off.
Switching waveform (pin 8) wrt ground.
Also, please share the complete layout files for layer-to-layer review.

Regards,

Vidhi

0 Vidhi Sharma 1 month ago in reply to Vidhi Sharma

TI__Intellectual 1720 points

Hi Ryu,

Any update for this?

Regards,

Vidhi

0 Ryu Yamashita 1 month ago in reply to Vidhi Sharma

Genius 4505 points

Hi Vidhi,

Sorry for not getting back to you sooner.
We have not received any information from the customer yet. I will have a direct discussion with the customer on Friday, and I will share any updates if available.

Best Regards,
Ryu.

Power management

Power management forum

TPS54338: TPS54338 Damaged (Burned Out)