TPS54160 UVLO filtering

Maurizio6434

Other Parts Discussed in Thread: TPS54160, TPS54260, TPS54140, TPS54240, TPS54160A

TPS54160 has a programmable UVLO.

I need to filter the EN pin because of a very dirty Vin, the best should be to put a small capacitor at the EN pin, but this practice is forbidden at pag. 15 of the d.s.

Actually I am testing the circuit with R1=470K R2=100K and a 10nF in parallel to R1. Vin max is 50V, I wander if this is a safe condition or I need to make same modification.

over 14 years ago

0 JohnTucker over 14 years ago

TI__Guru**** 191445 points

I would suggest that it would be better to filter the input voltage to ground rather than couple the ac into EN. You will have the benefit of less noise on the VIN as well as cleaner EN. Alternately you could program the start voltage and enough hysteresis into the EN (Vstart -Vstop) so that EN is not affected by noise on VIN. The voltage divider resistors should be ok. R1 is sufficiently high impedance to limit the EN pin current

0 Maurizio6434 over 14 years ago in reply to JohnTucker

Intellectual 295 points

Infacts calculations shows a 31uA into the EN pin at Vin = 50V, the EN pin voltage is 6,1V.

Question is: why the capacitor is forbidden? can it make any demage/malfunction to the chip?

0 Franco Zampicinini over 14 years ago in reply to Maurizio6434

Prodigy 110 points

And why this recommendation is not present on the TPS54260, TPS54140 and TPS54240 datasheets? Is the EN internal circuit different? From the datasheets they seems identical, but only for the TPS54160 there is the note about the capacitor on the pin and the detailed description of the internal zener.

Thanks.

0 JohnTucker over 14 years ago in reply to Franco Zampicinini

TI__Guru**** 191445 points

That is updated information. The other datasheets in that family will eventually be updated, but I do not have any schedule information regarding that.

0 trishankar thanikonda over 9 years ago in reply to JohnTucker

Prodigy 10 points

Hi,

I am facing the issue with Vstart and Vstop, I have calculated the resistor values as per the formula given in the data sheet, when i have used those values on my board the theoretical value is not matching with the practical results on the board.

I am looking for the Threshold voltage levels Vstart = 21.0V and Vstop = 14.6V, please suggest us resistor values to match these values.

Please help me in this regards.

0 JohnTucker over 9 years ago in reply to trishankar thanikonda

TI__Guru**** 191445 points

TPS54160 has very loose tolerance on the EN parameter. I suggest you try tPS54160A.

0 JohnTucker over 9 years ago in reply to JohnTucker

TI__Guru**** 191445 points

I can only suggest you use the datasheet equations. You can use the worst case values for EN threshold, and Ih and Ip in the datasheet to determine the range of actual start and stop voltages. I can tell you that the circuit works best with Vstart and Vstop separated by 1 or 2 V. Your range is rather large.

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TPS54160 UVLO filtering