This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS92662-Q1: Question for internal LDO

Part Number: TPS92662-Q1
Other Parts Discussed in Thread: TPS92661-Q1

Hi team,

In below figure, TPS92661-Q1 recommends that VIO(3.3V) should be tied to VDD(5V) when using 5V IO.  

-. Can you explain how VIO works when VIO is connected to VDD?

-. Does the VDD and VIO have Or-ing connection? If so, is VIO okay about reverse current of VDD?

Thanks,

Sam Lee

  • Hello Sam,

    The VIO pin sources current at 3.3V, if it is pulled above it cannot source current and VIO becomes the applied voltage, in this case 5V. It is intended to be used this way so VIO is okay with 5V applied for the TPS92661 as well as the TPS92662.

    "7.3.1.10 On-Board 3.3-V Supply (VCC Pin)
    The VCC pin is the output node of the on-board 3.3-V LDO. The VCC pin also acts as the positive voltage
    reference for the TPS92661 digital I/Os. If the TPS92661 is used with a microcontroller with 3.3-V I/Os, then
    place an output capacitor with a value of at least 0.1-μF at the pin for the internal LDO. Due to the internal linear
    regulator, the system does not require to provide a 3.3-V supply to the TPS92661.
    If the TPS92661 is used with 5-V microcontrollers, then the VCC pin MUST be tied to the 5-V VIN pin. This
    connection overrides the internal LDO and allows the digital I/Os to signal at 5 V rather than 3.3 V."

    BR,
  • Hello Irwin,

    Thank you for your answer. I want to double confirm one more about how VIO is protected for the reverse current from VDD. Does VIO have a blocking diode on the path?

    Thanks,
    Sam Lee
  • Hello Sam,

    It is an LDO, if you pull up on the output it reverse biases the linear MOSFET that would normally produce 3.3V.

    BR,
  • Hi Irwin,

    Thank you for your anwer. Let me ask one more question of the connection.

    When using VIN=5V, the datasheet recommends that VIN pin should be connected to VDD pin.
    In this situation, if TPS92662 is used with 5V I/O, does VIN pin have to connect the VIO pin together as well as VDD pin?

    Thanks,
    Sam Lee
  • Hello Sam,

    Yes it does however the 5V needs to be 5V not a range that can be higher.  It is the same function as connecting VIO to VDD, to avoid the LDO overhead voltage.

    Best Regards,