TPS61071: Damage after power on / off

Uli Hoss

Part Number: TPS61071
Other Parts Discussed in Thread: TPS62140,

My customer is using the following parts to supply a Davinci controller:

Main supply 12V - TPS62140 --> 3.3 V --> TPS61071DDC boost up to 5V --> TPS659113 supplies Davinci

If customer switches off the TPS62140 he got at some boards the next time when he switches on the supply voltage of 12V a "damaged" TPS61071, part is getting hot and the output voltage is round about 3 V (instead of 5V).

All TPS-parts are designed with capacitors @input/output pins, the TPS62140 is designed with ESD diodes at the input.

Does anyone had the same "mystic" behavior with a damaged TPS61071 ?

Actually the "moment of damage" is not clear, during switching on or switching off the main supply.

Thank you for your comments

Uli

over 7 years ago

0 Jasper Li over 7 years ago

TI__Mastermind 46905 points

1. measure the impedance between pins and GND to check which pin is damage
2. check the input voltage and output voltage TPS61071 during switching on/off the TPS62140 and TPS659113 to see if there is any over voltage behavior or strange behavior.
3. share me the schematic and layout of the TPS61071, i can find potential risk.

0 Uli Hoss over 7 years ago in reply to Jasper Li

Prodigy 20 points

Hi Jasper,

unfortunately the customer is not allowed to share the schematic, but he did some measurements with the defect part:

Best regards

Uli

0 Jasper Li over 7 years ago in reply to Uli Hoss

TI__Mastermind 46905 points

The SW shorts to GND in the failure IC, which normally mean the internal low side power switch is damaged.
Most of this power switch damage is caused by the over voltage at SW pin, which could be caused by the bad PCB layout.

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TPS61071: Damage after power on / off