TPS4H000-Q1: Behavior during current limit

Kuramochi-san,

The attached waveforms are what we would expect.

The reason the current is turning off and on is that the device is reaching the thermal swing shutdown threshold TSW that is defined in page 7 of the datasheet as 60°C. The device reaches this point, highlighted in yellow in the image below, and then shuts off. The part will cool down T_hys  and then try again due to the auto fault recovery as shown in the last row in the table below. After 1.52 seconds, the device hits TSD and the current remains off since THER is high.

Best Regards,

Elizabeth

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Kuramochi-san,

When the Tfet – Tlogic hits Tsw, the device turns off. The device doesn’t turn on until Tj drops Thys (10C).

However, because the Tlogic is heating up during this process as well (not as fast as Tfet), to reach the Tsw delta, the device will have to go to a higher absolute temperature during the next retry. The device is retrying so quickly it does not have time to cool back down and eventually it gets to the TSD point where it will remain off. Since there is not a way to measure Tlogic with this device, you will not know how much higher Tfet has to go to hit the Tsw threshold. Therefore, we cannot say exactly what the rise change in temperature you're referring to is. However, I hope this clarified the process.

Best Regards,

Elizabeth

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