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TIOL221: Boost output current of LDO

Ryuuichi machida
Guru 12640 points
Part Number: TIOL221
Other Parts Discussed in Thread: TPS7B69-Q1

Tool/software:

Hi,

I would like to confirm you have solution about my problem.

* Customer would like to configure whole system power by using LDO of TIOL221.
Customer's application is sensor, so they would like to reduce component as pssoible as they can.

They need approx 50mA for their system. According to ADI device MAX14829, they recommend to implement external transistor.
Is it possible to apply same way to TIOL221 ?

Best Regards, 
 

  • 0
    Guru 316690 points

    This is not possible. (The MAX14829 has separate REG/V5 pins to allow this.)

    What are the input and output voltages?

  • 0 in reply to Clemens Ladisch
    Guru 12640 points

    Hello,

    I did not hear exact input voltage, however output voltage is 5V or 3.3V.
    (Depending on system, but 3.3V tends to be used.)

    Best Regards,

  • 0 in reply to Ryuuichi machida
    Guru 12640 points

    Hi,

    I think I can realize similar circuit to connect base of Transistor to "VOUT" of TIOL221.
    What is difference "REG" function of MAX14829 and "VOUT" function of "TIOL221" ?

    BR,

  • 0 in reply to Ryuuichi machida
    Guru 316690 points

    The only way to get 50 mA is with an external power supply, e.g., TPS7B69-Q1.

    The VOUT pin is regulated to the selected output voltage, so the voltage at the emitter of the transistor would be lower.

  • 0 in reply to Clemens Ladisch
    Guru 12640 points

    Hello,

    Thank you for your reply.
    >The VOUT pin is regulated to the selected output voltage, so the voltage at the emitter of the transistor would be lower.
    I understood that MAX14829 may have output reguration function for emitter. However TI's one do not have such function(can not compensation for output voltage.)

    I also have idea that I can use OPAMP with voltage follower circuit.
    When we use LDO, input voltage may up to approx 30V, so dropout voltage is too high.
    Of course, we can use this, however I'm concern about thermal issue. Customer only need 50mA. So I think that OPAMP solution is comfortable than LDO.
    What do you think about this ?

    Best Regards,

  • 0 in reply to Ryuuichi machida
    TI__Guru 74252 points

    Clemens,

    Thanks for the help as always.

    Machida-san,

    Our IO-Link expert will be back in office on Monday, 05/19/2025, and will be able to take a look at this as well.

    Regards,

    Eric Hackett 

  • 0 in reply to Eric Hackett
    Guru 12640 points

    Hello all,

    Thank you for your support.
    >I also have idea that I can use OPAMP with voltage follower circuit.
    >When we use LDO, input voltage may up to approx 30V, so dropout voltage is too high.
    I was considering to use OPAMP. However, there is no device which have good thermal characteristic with small packge and satisfy acceptable supply voltage and output voltage current.
    So, I'm considering to make solution by using LDO(kinds of SOT223(bigger size than kind of SOT23) + TIOL221 as Clemens-san said.
    If you have any idea, could you let me know.

    Best Regards,

  • 0 in reply to Ryuuichi machida
    TI__Mastermind 33030 points

    Hello Ryuuichi,

    The use of an external regulator (either LDO or DCDC Buck) is the recommended solution when the application calls for more than 20mA of current on the low voltage supply (3.3V or 5V) preventing the use of the internal LDO through the TIOL221 VOUT pin.

    Regards,

    Jonathan