Hi Team,
My customer wants to use the TPS7A85 for low voltage regulation and we have the following questions :
1. Does it matter which voltage 3-6.5V we supply ? (e.g. any preference to 3.3/5V)
2. We wanted to ask whether the Vbias should be a clean voltage or is it possible to supply a non clean voltage from a switched DC/DC ?
How would this impact the performance of the LDO / PSRR ?
Regards,
Nir.
Hi Nir,
In order to have a regulated output voltage, Vin must be equal or greater than Vout + Vdo. As the headroom (Vin - Vout) increases, some specifications such as PSRR can increase; however, the power dissipation will also increase. The specific value of Vin will vary by application specific factors such as Vout, Iout, and what rails are available. What is your application's Vout and Iout?
Vbias has very high PSRR; therefore, it is possible to be supplied directly from a switcher. Keep in mind that for TPS7A85 Vbias is only required for low Vin.
Please consider the pin to pin TPS7A85A if your application will use the BIAS rail. TPS7A85A is more user friendly in that it does not have any sequencing requirements between Vin, Vbias, and Ven.
Very Respectfully,
Ryan
