TPS54821: load short mode operation

Toshihiro Watanabe

Part Number: TPS54821

Hello,

Our schematic is TPS54821 + 2A (typ) inductor configuration. In this configuration, we need to apply load short mode failure test.

In this situation, I think large current flow through switch and inductor which will be saturated.

Is TPS54821 and inductor damaged or degrated if the short mode test applied? If yes, what is thinkable?

Best regards,

Toshihiro Watanabe

over 6 years ago

0 Gavin Wang (Zejing) over 6 years ago

TI__Expert 3480 points

Hi Toshihiro,

You can use the inductor ensuring the inductor not saturated if you plan doing short test. The IC has hiccup protection when you do load short test.

Gavin

0 Toshihiro Watanabe over 6 years ago in reply to Gavin Wang (Zejing)

TI__Genius 10235 points

Hello Gavin-san,
I hope do so but our system has a limitation which can't use higher current one due to product form.
This is the background of this question. Is there any issue by applying short test?
Best regards,
Toshihiro Watanabe

0 Gavin Wang (Zejing) over 6 years ago in reply to Toshihiro Watanabe

TI__Expert 3480 points

Hi Toshihiro,
During power up,faults or transient load conditions, the inductor current can increase above the calculated peak inductor current
level calculated above. For this reason, the most conservative approach is to specify an inductor with a saturation current
rating equal to or greater than the switch current limit rather than the peak inductor current.

Gavin

0 Toshihiro Watanabe over 6 years ago in reply to Gavin Wang (Zejing)

TI__Genius 10235 points

Hello Gavin-san,
I guess well considered compensation setting is used, high-side and low-side MOSFET turn off so short event is no issue. Is my understanding correct?
Best regards,
Toshihiro Watanabe

0 Gavin Wang (Zejing) over 6 years ago in reply to Toshihiro Watanabe

TI__Expert 3480 points

Hi Toshihiro,
For the inductor saturation situations, only peak inductor current is triggered. High-side turn off by peak current limit.

Gavin

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TPS54821: load short mode operation