TPS784: ADC performance and LDO noise parameters

Mahabir Prasad

Part Number: TPS784

Dear Members,

It is open question to understand behavour of LDO with input from battery or mains adapter to same load charactestics with resepect o noise from LDO. I consider below important for High precesion ADCs.

1) RMS Noise, 2) Spot Noise and 3) PSRR

Does by using battery as input source, these parameters will be better, same or degrade further. In datasheets, it is never specified the nature of source while measuring them.

Regards

Dr. Mahabir Prasad

over 4 years ago

0 Stephen Ziel over 4 years ago

TI__Mastermind 37065 points

Hello Dr. Prasad,

The PSRR test uses an injection source, and sometimes a low noise amplifier, to sweep the injection on Vin and measure the attenuation on Vout using a VNA.

The noise measurements are typically completed using a 9V battery and shielded enclosure to minimize noise from entering the measurements. If a 9V battery is not used then we precondition the input power supply using a high PSRR linear regulator, so the input supply to the LDO under test is absolutely clean from conducted noise sources.

The following application notes may be helpful as well:

https://www.ti.com/lit/wp/slyy076/slyy076.pdf

https://www.ti.com/lit/an/slaa414a/slaa414a.pdf

https://www.ti.com/lit/an/slyt547/slyt547.pdf

Thanks,

- Stephen