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TXB0304: TXB0304 Part Marking and Current Consumption

Alex Ogle
Prodigy 30 points

Part Number: TXB0304
Other Parts Discussed in Thread: TXB0604, TXU0304

We are characterising low-power current draw in our system and observing the current draw when a state goes against a 'reccommendation' for the TXB0304.

When one rail is off and the other remains on, the current draw of the buffer may be higher (up to 300uA compared to the expected single-digit uA).

However, we are noticing a distinct difference between parts with different markings.

'737', '73R', and '73V' are all valid markings for the TXB0304RUTR and our units have a mix of '737' and '73R' (no '73V' that we have observed).

The higher-current state is quite probable with parts marked '737' but we notice that is is highly improbable where the part marked '73R' is fitted.

What is the significance of the part marking and why may it be leading to apparently different behaviour?

PXL_20260515_150021272.jpg

  • 0
    TI__Guru 56981 points

    Hi Alex,

    Can you provide more details regarding the test setup and how the 300uA is replicated? The part markings you have mentioned are legitmate part markings for this device, and share the same die:

    Regards,

    Jack

  • 0 in reply to Jack Guan
    Prodigy 30 points

    Hello Jack,

    We have a design where there are TXB0304RUTR between a processor (1.8V) and a short-range radio (3.3V - 2 buffers - 1 buffer for SPI and 1 buffer for UART + control lines), and the processor and a GPS chip (1 buffer for UART + control lines).

    In a low power state, the processor domain turns off and the radio domains remain on. We drive OE of the TXB0304RUTR low before turning off the processor domain but there is still a chance that the buffer will leak current from the 3.3V side through to the processor domain. Sleep current should be 90uA but we measure anything from 300uA ta 1.2mA depending on the number of buffers leaking and how much.

    The extra current draw is exactly the same as in these links...

    TXB0304: The power consumption of TXB0304 - Logic forum - Logic - TI E2E support forums

    TXB0304: High leakage current on TXB0304 when VCCB is off during system sleep mode while VCCA always ON. - Logic forum - Logic - TI E2E support forums

    I know the part markings are legitimate. However, there does appear (at least as far as we have seen) to be a difference between boards built with parts marked '737' and '73R'. If you say they are the same die then we will have to find some other difference that is leading to the stark difference.

    Boards with parts marked '73R' are almost all exhibiting sleep current between 90-150uA. The boards built with parts marked '737' have ~75% chance of higher sleep current (based on 3 buffers per board).

  • 0 in reply to Alex Ogle
    TI__Guru 56981 points

    Hi Alex,

     I will look into this and provide update shortly.

    Regards,

    Jack

  • 0 in reply to Jack Guan
    TI__Guru 56981 points

    Hi Alex,

    This is a documented issue in the past and the similar behavior to which you have observed is also replicated on bench. As a result, the datasheet was revised to suggest powering down both power supplies simultaneously to prevent the high leakage in current during power down:

    There is the updated TXB0604 that can be used here that resolves this issue, and offers P2P option (TXB0604RUT) in replacement of the TXB0304RUT. Could you see if this is suitable for your application as a more robust solution? 

    Regards,

    Jack 

  • 0 in reply to Jack Guan
    Prodigy 30 points

    Hello Jack,

    Thank you for the reply.

    We are aware of the issue with the TXB0304 and have tested and implemented the TXU0304 as a replacement (we can use unidirectional signals).

    However, my question was not about whether the part exhibits the leakage issue but trying to find out why we appear to be seeing a difference between parts marked '737' (with a reasonable probability that they will leak) and those marked '73R' (apparently very unlikely to leak with one supply off).

    You said they use the same die, but there seems to be some difference causing an apparent difference in behaviour.

  • 0 in reply to Alex Ogle
    TI__Guru 56981 points

    Hi Alex,

    Thanks for the update, I hope the TXU0304 is a better fit for your application. I understand your concern and I'll check in with the Design team to see if we can retrace the history of this leakage problem, and how it appears to be more prominent for part marking 737 and not 73R. 

    Regards,

    Jack