Hello,
I would like to know the PSRR parameter of the component TPS7A20, after the Dataheet, this parameter depends on the output current and the frequencies. I use this component to power my Hydrophone (I work in the 10Hz to 20kHz frequency band), what does the frequency parameter mean in this component ? Thank you for your helps
Regards.
Yann DO
Hi Nick,
Indeed it depends on the load current but also the frequency. Is this frequency parameter the operating frequency or the parasitic frequency ? At the input of this LDO component is a voltage coming from a lithium battery which, to my knowledge, there is no parasitic frequency. What does this frequency mean ?
After the DS, with I out = 20 mA, we have the different values of PSRR depending on the frequency.
Hi Yann,
To measure PSRR, an AC ripple is placed on top of a DC supply at the input of the LDO, and the AC ripple at the output is then measured. The ripple is swept across frequency to measure how well the LDO attenuates AC ripple from the input to the output. PSRR is then defined as 20*log(Vripple(IN) / Vripple(OUT)), such that the PSRR is a positive number.
Does that help you understand the PSRR spec? It is usually more informative to look at the PSRR vs. frequency plot instead of the Electrical Characteristics table, e.g. Figure 6-63.
Regards,
Nick
