TL431: PIN2 internal connection issue

Jason Fan

Part Number: TL431

Hi Bu:

i would like to know the internal connection of Pin2 in the SOT23-5 package like below picture, as the description of d/s, it is connected to the substrate .

Is the substrate internal connection electrically ? Can I think the PIN2 is floating internally ?

As customer's system requirement , there is the high voltage on the CATHODE , they don't expect the big voltage gap between the CATHODE and PIN2.

over 5 years ago

0 Marcoo Z over 5 years ago

TI__Mastermind 19610 points

Hi Jason,

The pin is connected to the substrate and non anode voltages can cause leakage. The options are to leave it floating or connect to anode.

Is this a creepage concern?

We do have alternate packages such as the SOT23-3 that have more spacing for creepage. is this a option?

0 Jason Fan over 5 years ago in reply to Marcoo Z

TI__Intellectual 1705 points

Hi Marcoo；

Yes, this is a creepage concern. Customer expect the CATHODE far away from other pin .

The SOT23-5 is the best package since the CATHODE is in the one side and rest are in other side. So can i think the substrate disconnected to any internal block of the device?

0 Marcoo Z over 5 years ago in reply to Jason Fan

TI__Mastermind 19610 points

Yes, the substrate will just be the bottom of the die based on how the lead package is made. it is not connected to any pad connecting directly to any circuitry.

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TL431: PIN2 internal connection issue