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TPS7B4253-Q1: Design Advice

Egemen Aksoy
Intellectual 975 points
Part Number: TPS7B4253-Q1


Greetings,

For the TPS7B4253 Input voltage will be between 6.3 - 7.7V, and the corresponding output voltage between 4.5 - 5.5V.

With this output I would like to provide supply to an sensor IC that requires 5V nominal supply. The output of this sensor IC is ratiometric.

I will scale down to input voltage by R1 = 4k, R2=10k resistors.

Then I will raise the output voltage of the sensor IC again by using OP-AMP. For this purpose I want to use this voltage tracker LDO. Is it okay?

The output of the whole circuit should be ratiometric even up to 7.7V.

For scaling down I did not choose an OP-AMP because of the capacitors in supply of sensor IC.

Is this configuration okay or do you have any other solutions or recommendations?

  • 0
    TI__Mastermind 18466 points

    Hey Egemen, 

    Thank you for being patient in this response. 

    From the first part of your question, it seems like you are just using your VIN voltage through a voltage divider to provide the appropriate adjust value. There is no issue with that.  

    Egemen Aksoy said:
    The output of the whole circuit should be ratiometric even up to 7.7V.

    When you say that, do you mean you want the output voltage to track the voltage as it goes up to 7.7? Or do you mean that even when the input is 7.7, you want the output to be 5.5V? Because if you want the output to stay at 5.5V regardless of the input, you will have to find an alternate way of connecting the circuit. Potentially an LDO supporting the ADJ pin. 

    Egemen Aksoy said:
    For scaling down I did not choose an OP-AMP because of the capacitors in supply of sensor IC.

    Could you clarify what this means?

    Best,

    Juliette

  • 0 in reply to Juliette
    Intellectual 975 points

    The sensor IC has ratiometric output with 5V supply. I would like to have the output of the sensor IC to track VIN(up to 7.7V). For this purpose I will add an OP-AMP to the output of the sensor IC with 1.4 gain. In other words I would like to operate the sensor IC ratiometricly like it is working with 5V supply.

    For scalling down, OP-AMPs may not be suitable since there are many capacitors(bypass/decoupling) at supply pins of the sensor IC. Most OP-AMPs are not capable of driving capacitive loads. Thats why I prefer to use voltage tracker LDO.

    Do you think this solutiıon is okay or do you have any other recomendations?

  • 0 in reply to Juliette
    Intellectual 975 points

    Hi

    Is there any progress for this question?

  • 0 in reply to Egemen Aksoy
    TI__Mastermind 18466 points

    Hi Egemen, 

    I was out of office and it seems like other people in charge of E2E were also out. 

    Your applications seems like this LDO will be ok. 

    Best,

    Juliette