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ADS1299: Analog Supply Voltage for battery-powered application

user4702816
Prodigy 10 points
Part Number: ADS1299
Other Parts Discussed in Thread: TPS60403

Dear TIs,

I am planning to use three ADS1299 for an application, where a single Lithium Ion Battery (3,7V nominal) shall be used as the power source for the whole design. Several voltage rails needs to be generated out of this source (1V2, 1V8, 2V5, 3V3) on top of the AVDD needed for the ADS1299. From the datasheet I learned that the ADS1299 offers two options for the AVDD: 5V/0V or +2V5/-2V5.

Initially, I planned to implement to boost the voltage level to 5V using a switching regulator. Afterwards I realized that on the ADS1299-EVK, which already has a 5V rail from USB-power, uses the TPS60403 charge pump inverter to generate -5V which is then used as the input of a LDO to provide the needed -2V5 (in addition of a LDO for +5V -> +2V5). 

This said, I was wondering if one configuration has advantages over the other and why the above described solution has been chosen for the EVK. 

Thank you and best regards
- Marc

  • 0
    TI__Mastermind 49431 points
    Hello,

    Welcome to the forum and thanks for your interest in the ADS1299!

    Both supply configurations are acceptable and there are no performance advantages for one configuration over the other. The solution was chosen for the EVK to demonstrate the supply voltage flexibility.

    When working on your actual circuit, one thing that I would verify is that your supply voltage is regulated and running at the expected value. For example: a 5V USB will sometimes have a small amount of error, it could actually be 4.9V or 5.1V etc. This can cause issues if your FSR is set to an epected AVDD to AVSS value of 5V-0V, but is actually 4.9V-0V. However, in the case of the EVK the LDO's should properly regulate the voltage and it shouldn't be a problem for testing purposes.