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TPS65094: TPS65094 voltage issue

Jeff YANG
Mastermind 7085 points
Part Number: TPS65094

Hi,

Currently, due to Intel Apollo Lake stepping up to F-1, we observed that after the replacement, the frequency can only reach 2.2 GHz or 2.1 GHz, instead of the 2.4 GHz in B-1.

The multiplier seems to be stuck at 21-22 and cannot reach 24. When measuring, we noticed that both sets of VCORE voltage are slightly higher than in B-1. There don't appear to be significant differences in other BUCK components.

We are currently using TPS650942 & TPS650947, and it seems that both are facing this issue.

What could be the possible reason for this? Do we need to modify any settings in the PMIC.

By checking through PMIC_I2C, we found that the F1 CPU writes a voltage value higher than the previous B1 version during the boot BIOS stage.

After entering the boost state to run at the highest frequency, the original B1 CPU writes a stable voltage value directly.

However, the F1 CPU continues to cycle rapidly, switching between two levels with a 0.01V difference.

There have been no specification changes on Intel's side, and we suspect it may be due to IMON differences.

However, TPS650942/650947 do not have an IMON pin that can be configured.

What could be the reason for the PMIC continuously sensing and adjusting the voltage? The peripheral circuits are all the same.

Thanks!

Jeff

  • 0
    TI__Mastermind 20300 points

    Hi Jeff,

    The PMIC does not control the voltage adjustments, it only responds to I2C commands or physical inputs to the control pins. It can shut down in response to a fault but fine tuned changes to the voltage come from the outside. All the write commands being sent to the PMIC are coming from the Host device since the PMIC is a slave IC in this case. The PMIC will remain in its default configuration unless an I2C command is sent by an external source.

    If the registers are being changed repeatedly, it will have something to do with the Apollo Lake protocol. The first step would be to figure out why the new CPU is behaving differently than the old version. If the new F1 stepped CPU is a drop-in replacement, the behavior should remain the same as the old CPU at a basic level.

    Regards,

    James