TPS2663: Capacitive Load into thermal regulation

Khoi Nguyen

Part Number: TPS2663

Tool/software:

Hi, in my application, Im trying to connect a TPS2663x to a motor controller board which has 10mF of capacitor on board with 200W max. Using the calculator, I noticed that the device will go into thermal regulation at startup due to inrush current. Refer to the application note: https://www.ti.com/lit/an/slvaeb9a/slvaeb9a.pdf, I would say it is expected but I wonder if it would put a stress on the internal FET of the eFuse? Plus, how long would it take to get out of thermal regulation then? Is there any other step I should take to limit the inrush current?

I have attached my calculator sheet for reference.

PTU_TPS2663x _TPS1663x_Design_Calculator_revB .xlsx

10 months ago

0 Amrit Jit 10 months ago

TI__Mastermind 30681 points

Hello Khoi,

You can reduce the inrush current by using appropriate dVdT cap.

Have you tried that in design calculator?

Thermal regulation loop depends on power dissipation in internal MOSFET. It depends on the inrush current profile.

You can try it on TPS2663-33EVM board.

Thanks

Amrit

0 Khoi Nguyen 10 months ago in reply to Amrit Jit

Prodigy 30 points

Hi Amrit,

Thanks for the quick reply. I understand that selecting a larger dv/dt capacitor would limit the permissible inrush current, which in turn increases the charging time to the output capacitor. However, I’m unsure whether the device can exit thermal regulation under these conditions.

I noticed a case where the device failed to start up with approximately 1.5mF of output capacitance: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1283767/tps2663-thermal-protection-will-be-triggered-during-startup

Unfortunately, I don’t have an EVM available to verify this.

0 Amrit Jit 10 months ago in reply to Khoi Nguyen

TI__Mastermind 30681 points

Hello Khoi,

Sorry for the delay in response.

You can refer the below app note which explains start-up with large capacitance. TPS2663 is also included.

https://www.ti.com/lit/pdf/slvaeb9

Thanks

Amrit

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TPS2663: Capacitive Load into thermal regulation