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TPS7B4253-Q1: why do we need voltage tracking LDO?

justifice zhou
Intellectual 400 points
Part Number: TPS7B4253-Q1

I'm reading SLVA789 article.

In "Typical Application for Voltage-Tacking LDO" part.

"it is necessary to keep the voltage-tracking tolerance between the off-board sensors power supply and the MCU/ADC power supply to the lowest level"

But if we remove the voltage-tracking LDO, and we use one DC/DC or LDO to power both ADC and off-board sensor, the voltage should be identical, the voltage difference should be even smaller?

  • +1
    TI__Mastermind 37965 points

    Hello,

    You are correct. However, if the tracker is removed, the ADC reference voltage is exposed to the off-board connections, which are prone to faults such as short-to-battery or short-to-ground. So, the tracker LDO serves as a buffer that keeps the reference voltage within a tight tolerance for the sensor supplies while also isolating the off-board connections to help protect the ADC. 

    Regards,

    Nick