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TPS552892: When selecting internal VCC power supply, the chip will have leakage from VIN to VCC

Maple TAN
Prodigy 20 points
Part Number: TPS552892

Hi team，

      During our testing process, we found that if 552892 is changed to internal VCC power supply (EXTVCC pin connected to VCC pin), there will be leakage in the VCC. After investigation, the leakage of the VCC comes from the VIN, belonging to the internal leakage of the 552892 chip, with a maximum leakage amplitude of about 500mV.
      We tested multiple 552892 chips on the EVM board and two project boards, all of which had this issue.
      Figure 1 shows testing our own PCB board, disconnecting both PG and EN; Power up the VIN and test the VIN(yellow) and VCC(blue).
      Figure 2 shows the EVM board tested, with EN disconnected; Power up the VIN and test the VIN(green) and VCC(blue).

      Does this internal VCC leakage have an impact on the normal operation of the chip? Is there a risk?

      Thanks.

  • 0
    TI__Mastermind 34201 points

    Hi,

    1. When EN=high, the device will regulate the VCC voltage to 1.2V first no matter EXTVCC is connected to VCC,  floating or 0V. The reason is in the case of EXTVCC is connected to VCC (select internal LDO), if VCC is not regulated to 1.2V (above EXTVCC input logic high threshold), the device cannot select internal LDO.

    2. There is no risk of the 1.2V on VCC. When selecting external supply for VCC, a 5V needs to connected to VCC pin.

  • 0 in reply to Zack Liu
    Prodigy 20 points

    Thank you for your answer. And the email from FAE also answered the reason for the leakage of approximately 500mV in VCC. At present, all issues have been resolved. Thank you.