PMP10282: Estimation of cable compensation

Part Number: PMP10282

Hi,

We got a question from customer about PMP10282.
Could you help us?

[Question]
They consider to design cable compensation refer to PMP10282 which is INA213-Q1 and TPS54340-Q1. They want to estimate the voltage regulation and the variation.
If you have estimation tool, could you provide us?

Best Regards,
tateo

5 Replies

  • Hi, We need your help. I would appreciate it if you could provide your feedback.

    Best Regards,

    tateo

  • In reply to tateo yamashiro:

    Please see attached EXCEL file with voltage droop calculations.

    Droop Comp TPS54340.xlsx 

  • In reply to John Betten:

    Thank you for your support. Your excel sheet is very helpful.
    By the way, I have a question. I calculated P/S reg on condition that the PMP10282 schematics.
    There is a deviation between calculated value and test report. What is the cause of this deviation?

    Best Regards,
    tateo

  • In reply to tateo yamashiro:

    The test report voltage regulation data shows the measured output voltage at the two locations. The green line is across C8, which is the output of the TPS54340 buck converter and increases with output current. The red line is at the connector J3 - pin 1 on the EVM. This point is on the EVM itself and represents the voltage drop after C8, which includes the voltage drop of current sensing resistor R3 and the voltage drop through U3. It does not represent the voltage at the end of a USB cable. To get the voltage at the end of the cable, where the regulation will be close to constant, you need to know the contact resistance between J3 and the USB cable, the resistance on the USB cable itself, the contact resistance on the user end of the USB cable, and any additional resistive drops (such as PCB traces on the user end). This total resistance is approximately 0.28 ohms, but can vary with cables and must be carefully measured for accurate droop compensation results. Just subtract this additional voltage drop from the red line in the test report to find the voltage at the user end. The output voltage can be adjusted up or down by using the spreadsheet already provided.

  • In reply to John Betten:

    Hi, I compared both green lines which is output of TPS54340. There is several tens millivolt deviation. What is the cause of this deviation?
    Can we estimate the voltage regulation with high accuracy?

    Best Regards,
    tateo