TLV62565: OCP for inrush current

Hirotaka Inoue

Part Number: TLV62565

Hi support member,

My customer concerned TLV62565 OCP for inrush current.

The inrush current is very close to 1.8A.

My understanding is that above condition is no problem, because Hi-side FET will become to turn off if that is over the current limit.

The allowed maximum current limit expected 2.8A as following thread.

https://e2e.ti.com/support/power_management/non-isolated_dcdc/int-non-isolated_dcdc/f/198/t/423418?tisearch=e2e-sitesearch&keymatch=TLV62565

Is above my understanding correct?

Regards, Hirotaka Inoue

over 8 years ago

0 Emmanuel Granatello over 8 years ago

TI__Expert 3465 points

Hi Hirotaka Inoue,

thank you for sharing your concerns. Your understanding is partially correct. Actually in the post you can see that 2.8A is not the allowed maximum current limit expected, but what we have observed so far. The datasheet does not specify a max value for the current limit.

By the way, as soon as the inductor on your customer application does saturate, the behavior of the device is safe and in normal operation.

Best regards,
Emmanuel

0 Hirotaka Inoue over 8 years ago in reply to Emmanuel Granatello

TI__Intellectual 2980 points

Hi Emmanuel-san,

Thanks for your answer.

If inductor current reach High-side FET peak current limit, will device go to shutdown?

Best regards, H.Inoue

0 Emmanuel Granatello over 8 years ago in reply to Hirotaka Inoue

TI__Expert 3465 points

Hello Hirotaka-san,

Thank you for the interesting question!

When the device is in High side current limit, the high side turns of, but the device continues it's working operation. As a direct consequence the the duty cycle is reduced, so the output Voltage is not anymore regulated by the feedback loop, but drops down to a value more proportional to Vin, inductance value, switching frequency and current limit.

Best regards,

Emmanuel

0 Hirotaka Inoue over 8 years ago in reply to Emmanuel Granatello

TI__Intellectual 2980 points

Hello Emmanuel-san,

Thanks for your answer.

Is it means that output voltage is regurated again as soon as the device reach Low-side valley current limit?

Best Regards, H.Inoue

0 Emmanuel Granatello over 8 years ago in reply to Hirotaka Inoue

TI__Expert 3465 points

Hello Hirotaka-san,

You are welcome.

This time your assumption is not correct. The output voltage is regulated again as soon as the High side current limiting does not take place anymore, that means when the inductor current drops down. At this point indeed the duty cycle is regulated by the control loop, while before it was "limited" by the peak current current limitation.

Best regards,

Emmanuel

0 Hirotaka Inoue over 8 years ago in reply to Emmanuel Granatello

TI__Intellectual 2980 points

Hello Emmanuel-san,

Thanks for your answer.

Best Regards, H.Inoue

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TLV62565: OCP for inrush current