SN74LVCH16T245: SN74LVCH16T245DGGR – Unexpected low resistance between VCCA and VCCB

Hi TI team,

I’m using the SN74LVCH16T245DGGR in a level-shifting application with the following configuration:

• VCCA = 1.8V

• VCCB = 3.3V

However, I’ve observed an unusual issue:

• When I apply 3.3V to VCCB, the VCCA rail rises immediately to 3.3V, even when I’m supplying 1.8V or leaving it unconnected.

• I measured the resistance between VCCA and VCCB (before soldering the ICs), and it’s consistently less than 2 ohms.

• This behavior occurs on 6 different ICs, all using ICs from the same batch.

• The top marking on the IC is: “65A1DCK” (package: TSSOP-48).

From the datasheet, VCCA and VCCB are supposed to be independent, so I would not expect this kind of interaction.

Could you please help clarify:

1. Whether this resistance is expected or normal for this part?

2. If this behavior might be due to internal protection features, or possibly ESD structures?

3. Whether the “65A1DCK” marking corresponds to an official TI lot?

I’d appreciate your insights before proceeding further with hardware debugging.

Thank you in advance!

Best regards,
[Andi Mei]