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TPS65296: VDDQ Output

user6342548
Prodigy 160 points
Part Number: TPS65296

Hi Team，

For lpddr4x power supply, the vddq output of the chip is 0.603V. Please confirm how to output VDDQ to 0.62V?

  • 0
    TI__Expert 5470 points

    Hi,

    With internal 0.6V reference voltage, the only method to adjust VDDQ to 0.62V is to add voltage divider for VDDQ voltage feedback.

    But for TPS65296, we haven't met case for application like this. We need to check with design team whether there's any concern. Could you share some information about the application? Why is the 0.62V needed?

    Thanks,

    Andrew

  • 0 in reply to Andrew Xiong
    Prodigy 160 points

    Hi Andrew，

    For lpddr4x, we hope the voltage of VDDQ can be increased to ensure the stability of DRAM. At present, the VDDQ(0.603V) measured on the board is somewhat low.

  • 0 in reply to user6342548
    Prodigy 160 points

    Hi Andrew，

    And help explain what this current means?

  • 0 in reply to user6342548
    TI__Expert 5470 points

    Hi,

    You can refer to the block diagram of datasheet. There are discharge MOS inside IC to prevent the external force voltage. With external bias voltage, it will affect the timing and sequence of the three power rails. So we want to make sure that the bias voltage of each channel can be discharged before startup.

    Using a internal mos for the discharge, all the power will consume on the Rdson of the mos. So the discharge current are both affected with the external bias voltage level and the junction temperature which has effects on the Rdson. The diagram here shows the relation between discharge current and junction temperature (with higher junction temperature, Rdson will go higher and discharge current will become smaller).

    For the 0.62V output request of the VDDQ, I think you can try to use feedback resistor divider from VDDQ to VDDQSNS to get the 0.62V output. There's no obvious concern theoretically.

    Regards,

    Andrew