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ADS1298ECGFE-PDK: Bipolar Operation TP6 -2.5V

Hong Tay
Expert 2465 points
Part Number: ADS1298ECGFE-PDK

Hi Sir/Madam,

Is there necessary to invert the voltage from +5V to -5V and step down to -2.5V? Is there any way to convert 5V to -2.5V directly? My customer is asking for board space saving.

Thanks.

  • 0
    TI__Guru 66186 points

    Hello Hong,

    Thanks for your question.

    I'm not an expert on power supply designs. From the ADC's perspective, what matters is the final output voltage seen by the AVSS supply pins. You may see a decrease in ADC noise performance if the supply comes directly from a switching DC-DC converter vs. from an LDO. The power supply design on the EVM was probably chosen to suppress the switching noise from the DC-DC converter and improve power-supply rejection: +5 V -> -5 V (from DC-DC) -> -2.5V (from LDO). This is common practice for important supply rails.

    Have you seen our Webench Power Designer page? This may give you some more ideas about possible solutions that would save on board space.

    Best Regards,