TPS62150A: SW pin absolute maximum ratings

Hi Koichi,

Abs.max SW of "VIN+0.3V" is DC value. When the power turned from ON to OFF. The super cap in VOUT would charge to input cap, so SW is nearly equal to VIN. This wouldn't exceed Absolute Maximum Ratings.

Thanks,

Colin

Thank you for your reply.

When you say "because the VOUT supercap charges the input cap," are there any constraints on time or capacitance?

Also, when you say charging from VOUT to the input, does that mean it passes through the body diode attached to the FET inside the IC?

Best Regard,

Hi Koichi,

Yes, the charging from VOUT to the input cap will pass through body diode of high side FET. 

After power off, the input cap can keep voltage as well, so it wouldn't be a constraints on time or capacitance.

Thanks,

Colin

Thank you for your reply.

Please tell me more about the droop of the input power supply.
I assume that the comment "After power off, the input cap can keep voltage as well," assumes that the voltage is maintained by the capacitor at the external input of the IC. The condition I am asking about is, if the output voltage has a residual voltage of 1.8V even after the input voltage has drooped to 0V, is there a limit to the time or current value that the current flows through the body diode?
Thank you in advance.

Best regards,

Hi ,

Although VIN is 0V,the VOUT can charge to CIN through body diode. It can equal to a model about power charge to cap through diode.

The current and time can be calculated by VOUT, CIN,  feedforward voltage drop of diode.

Hope you can understand.

Thanks,

Colin

Thank you for your reply.

Looking at the conditions you stated, is it correct to understand that under those conditions "Pin voltage: SW MAX=VIN + 0.3V" in "7.1 Absolute Maximum Ratings" does not apply?

Best regards,

Thank you for your reply.