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.

TPS2547: How can we use the Status pin

Part Number: TPS2547

Hi team,

I have a question with TPS2547 Status pin when feeding back to customer's questions.

My customer wants to use the status pin to realize a feature to boot the system the first time if the current drawn from 2547 power rail is larger than 300mA.

I suppose this can be realized by regulating the ILIM_LO setting right?

But also seems that there is still another current threshold as 45mA and 55mA for the load detect also works and change the Status pin level. Could you help to explain to me how the status pin is triggered please?

If the 45mA/55mA is the threshold? Or any situation that the ILIM_LO and the 45/55mA are separately used?

Thanks for your help

Max

  • Hello Max,

    The 45mA threshold you are referring to is for the Power Wake feature built into the device, which can be read in section 8.3.6 of the datasheet. This feature is only enabled when the device is in S4/S5 power state

    All other configurations, the STATUS pin is set based on the PPM feature which determines when STATUS goes low based on threshold set by ILIM_LO + 60 mA. So for your customers application, keep the device in CDP charging mode or DCP_Auto with the ILIM_LO + 60 mA current threshold and your customers system should be fine.

  • Hi Adam,

    Thanks very much for your explanation. And need to double confirm with you. If the ILIM_LO is open, is that mean the lower limit is down to 0+60mA?

    And customer also mentioned to me that in S0 status when leacing the port free (not connected), they can see status pin pulled-low sometimes. And after changing the capacitor close to the port which is around 150uF from Bulk to MLCC, this phenomenon disappear. I'm still checking on details and request some more tests and captures from customer to explain the test, phenomenon and results. And come to you in advance to check if there are potential risks on triggering STATUS pin if Bulk capacitor is used (in Type-A port not connected case).

    Thanks 

    Max

  • Hi Adam, 

    Besides questions in above message. I get some more questions need your help to confirm.

    1. The 45mA trigger point is related to the power wake function. And there is also another USB wake feature. Are they related or totally different? Could you help to explain how the USB wake (mouse/keyboard wake) is realized please? 
    2. We keep ILIM_LO pin as floating, so ILIM_LO=0, means that ILIM_LO+60 mA about 60mA when no BC1.2 primary detection?
    3. When doing BC1.2 primary detection, what suppose to be the trigger point of STATUS pin ? Is it defaulted at 45mA power wake value or ILIM_LO? Or maybe depend on the real time CTL and ILIM pin levels?

    Thanks

    Max

  • Hi Adam and team,

    Double confirmed with customer that in CDP configuration and system S0 status, they monitored that the configure pins and Vbus not changed, but the status pin will pull-low sometimes in the case that nothing is connected to the USB-A port and and ILIM_LO is floating, this has been the issue need to be cleared very soon. 

    Below is the schematics, could you help to confirm if there are any posibillities that can trigger the STATUS pin? Please let me know if you need more test to clarify. 

    Thank you.

    Max

  • Hello Max,

    Your customer needs to populate a resistor on ILIM_LO. As outlined within the datasheet, this pin is optional if the following two criteria are met.

    1. ILIM_SEL is always set high

    2. Load Detection - Port Power Management is not used

    Since your customer does not meet either of these requirements, they will need to populate the resistor on ILIM_LO. This should fix the issue.