TPS54335A: Input, Output voltages

Eriks Austrums

Part Number: TPS54335A
Other Parts Discussed in Thread: TPS65982

I have the following circuit http://www.ti.com/lit/df/tidrgw6/tidrgw6.pdf, where External Power is 5 - 20V and HV_Source gives 12V. HV_Source is connected to a input pin on TPS65982. The problem is that i need to configure the TPS65982 pin as output and i need to know , what will happen if External Power will be 0V (unconnected) and HV_Source is 5V. Is there risk of destroying the TPS54335 chip and if so , what should i do to safely test this? Unsolder L4? or just pull down the EN pin? Also what would happen if External Power would be like 5V input and HV_Source would be 5V input? Any help is appreciated.

over 4 years ago

0 Shawn Nie over 4 years ago

TI__Genius 10070 points

Hi,

The input capacitor would be charged through body diode of high side FET, there is no risk to damage the IC, it would be better to set the threshold voltage of ULVO higher than 5V, also you can add a diode to prevent this behavior.

Shawn

0 Eriks Austrums over 4 years ago in reply to Shawn Nie

Intellectual 675 points

The thing is, when i accidentally supplied 5V on External Power and supplied 5V on HV_Source , the IC cracked and let out magic smoke.

Just want to be sure, if i have 0V on External Power, and there is 5V on HV_Source , will the IC ignore it.

0 Shawn Nie over 4 years ago in reply to Eriks Austrums

TI__Genius 10070 points

Hi,

If you force input voltage to 0V, and output voltage to 5V, the high side FET would be damage because of the large current go through the body diode.

If you float VIN, the IC would not be damage.

Shawn

0 Eriks Austrums over 4 years ago in reply to Shawn Nie

Intellectual 675 points

Thanks a lot Shawn, all i needed to hear. The fact that i had the R101 and R103 resistors soldered in is probably the reason why the IC died .

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TPS54335A: Input, Output voltages