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TPS23881: I have a user requirement of configuring power budget on a port as per user's request,Is it possible?

Part Number: TPS23881


Hi,

The issue we are facing it we are allocating power budget per port based on PD'S class.

class 1          4W

class 2          7W

class 3          15.5W

class 4          30W
But due to this,we are running out of total PSE power budget because actual power consumption is less but power allocated is higher (e.g a class 4 PD has been allocated 30W but consuming only 3.9 W).We have 270W power budget and by connecting 9 class 4 PDs,our power budget is exhausted whereas actual power consumption is only 4*9=36W.

So,we wanted to configure power budget not based on class of PD but as per our wish,we want to set power limit on a port,can we do so?can we set this using power policy register so that if PD connected exceeds that power configured,it should power off?


This is an urgent thing so pls take this on priority.

I will simplify the requirement.
Let's say a class 4 PD is connected so as per class,we can allocate 30W.

User wants to allocate only 5W as PD is actually consuming 4W ,what are the steps we can follow to do so?


Also,pls throw some light is it valid thing to do as per the protocol?

Regards 
Ayush Raj

  • Hi Ayush,

    There are multiple ways to do this however, this is a system level requirement. We currently use our FirmPSE black box solution to achieve dynamic power monitoring which monitors the active power being consumed on the port and adjusts the PCUT threshold accordingly.

    The best way to achieve this would be monitor the power being consumed on the port and adjusting the pcut threshold. 

    Reading into registers 30h-3Fh will give you the current and voltage for each channel. From here, you can calculate the power being consumed on the port.

    Once you have the power being consumed, adjust the 4-P and 2-P PCUT thresholds accordingly.

    This should achieve "dynamic" power monitoring and allow your system to use full power budget. 

    Regards,

    Brandon