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TPS767D3: Can TPS767 ouput 1.2V?

Marsh Cai
Expert 3285 points
Part Number: TPS767D3
Other Parts Discussed in Thread: TPS767, TMS320F28374S

Hi Experts,

Due to the severe supply shortage of TPS73HD301, we recommended TPS767d301 to customers. However the LDO is used to power the core of C2000 28374s, so output 1.2V is required. But, I checked the datasheet that the lowest output of TPS767D301 is 1.5V. Customer feedback that TPS767D301 can output 1.2V successfully with 5V input, which is beyond the limit of the datasheet.

So now, customer's questions are:

1, Why TPS767D301 cannot output 1.2V? The datasheet shows that 767D and 73HD share the similar vref voltage 1.18V. Why the lowest outputs voltages are different?  

2, Why TPS767D301 can output 1.2V in actual test. What are the potential risks of this configuration? 

BRs

Thanks

  • 0
    TI__Expert 3285 points

    Hi Teams,

    The required output for the LDO are: CH1, 1.2V@750mA. CH2, 3.3@750mA.

    Looking forward to your great reply.

    Marsh

  • 0 in reply to Marsh Cai
    TI__Genius 12535 points

    Hi Marsh, 

    These two devices are completely different, they do not share same die, therefore, the internal circuitry is completely different, even if they have the same reference voltage. 

    I'm currently looking into this, however, both are really old devices, and it is really difficult to obtain any data. 

    Furthermore, we cannot guarantee any specs outside what is listed on the DS, even if the device seems to work at the given conditions. 

    I will respond back as soon as I can obtain more information. Please be aware that this will take some time. 

    Best, 

    Edgar Acosta

  • 0 in reply to Edgar Acosta1
    TI__Expert 3285 points

    Hi Edgar,

    Do you know the history of this? I found a very similar thread about TPS767D301 in E2E, you can check it via this address.

    https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/945008/tps767d3-any-questions-about-using-tps767d301-and-wson6-package-ldo-for-the-power-source-of-tms320f28388d

    And right now, we all know this is not recommended, but this is maybe the only option for my customer, so you great help is very important and very appreciated. 

    Currently what customer want to know is the potential risks of this configuration when be use in 1.2V output.

    You can contact me by email, if it works better for you.

    Thanks a lot. 

    Marsh.

  • 0 in reply to Marsh Cai
    TI__Genius 12535 points

    Hi Marsh, 

    From the E2E post, it seems that there was a test change therefore Vout min changed. Overall, I agree, if Vref is 1.18V, then 1.2V should be doable. 

    I'm still looking into why this change was implemented to properly address the potential risk (if any). 

    Feel free to reach out by email if that is more suitable. 

    Best, 

    Edgar Acosta

  • 0 in reply to Edgar Acosta1
    TI__Expert 3285 points

    Hi Edgar,

    Thanks for your help. some more questions may need your help.

    1, I noticed that the Vref range of TPS73HD301PWPR is 1.147~1.217 within whole temp range -40~125°C. But in 25°C, there’s only typical value 1.182V. Do we have the data of the part-to-part difference of the vref in 25°C?

    2,Do we have the vref range data for TPS767D301, which is not shown in theD/S?

    3, What’s sequence of the ch1 and ch2 once TPS767 powering up? Can it meet the requirements of powering the TMS320F28374S(see the pic below).

    Thanks & BRs

    Marsh

  • 0 in reply to Marsh Cai
    TI__Genius 12535 points

    Hi Marsh, 

    I have responded over email. 

    In regards the startup time, I do not know and there is no test data for this. This will have to be tested under the bench to obtain the data. As explained over email, it would require a startup time of ~3.6ms in order to meet the minimum 330V/s or 12us to meet the 10^5 maximum requirement. 

    There is an app note: 

    Using the TPS767D325 LDO Regulator (ti.com)

    That shows the sequencing time from Ch1 and Ch2. This could provide some insight. 

    Best, 

    Edgar Acosta