• State TI Thinks Resolved
  • Locked Locked
  • Replies 3 replies
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 522 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS61256C: BP bypass pin works contrary to what stated in the TPS61256 datasheet

Nevio Daneluz
Prodigy 40 points
Part Number: TPS61256C
Other Parts Discussed in Thread: TPS61256

ic: TPS61256C


We are using this step-up dc-dc converter in the USB outputs of a device, with 3.3-4.2 V input and 5 V output. We have noticed that the BP bypass pin works contrary to what stated in the TPS61256 datasheet, i.e .:
- EN low, BP high: 0V output
- EN low, BP low: output in bypass
- EN high, any BP: power supply on, 5V output.

Looking online, I saw later that there is also a datasheet referring to the "C" model, the TPS61256C, which is actually what we are using, and in that the ball BP is renamed GND!
Now I ask you, since I need the bypass function, and also need to disconnect voltage at the outputs, can I drive BP pin high and low to turn it off and put it in bypass? I ask you this because from what I have tested it works. Or are there any contraindications / defects that I don't know that could give me problems in the future?


Thank you

  • 0
    TI__Genius 9046 points

    Hi Nevio sir,

    There is no BP pin for TPS61256C. Please strictly follow what has been described in datasheet. 

    If you need to use standby function. Please use TPS61256 instead. 

    Also note EN low, BP high TPS61256 is going to be standby mode which  allows input to limitedly bypass to output side with 150mA current limit.

    -Wenhao

  • 0 in reply to Wenhao Wu
    Prodigy 40 points

    Hi Wenhao,

    the bypass pin in that component is there, and there is no question about that. It works. It is clearly a control pin and not a real ground pin. Like its brother TPS61256.
    You can tell me that I discovered it by chance, ok this is true, and it is also true that the datasheet says that that pin does not exist and that ball must be grounded. Ok. But the facts say that bypass pin is there, and it works as a bypass!
    So my question is: can you give me some more info on that pin? Can I use its as a bypass? Or should I expect it to work sometimes and sometimes it doesn't, i.e. you guarantee me it will work?
    I ask you because I am in a situation where I have TPS61256C mounted on 2000 pcb instead of TPS61256 and I have to understand if I can guarantee it will work in that way or not.

    If you tell me that that pin should not be used as a bypass but it still works, I keep the 2000 devices as they are, while if you tell me that one in ten can give problems, then I am forced to withdraw all 2000 devices and rework them.

    Thank you again

    Best regards

    Nevio

  • 0 in reply to Nevio Daneluz
    TI__Genius 9046 points

    Hi Nevio,

    Sorry, we cannot guarantee the performance or spec which is not within datasheet.

    -Wenhao