Q: TPS799xx use as a voltage limiter by 698145

Can I use the TPS79942 as voltage limiter.

input voltage from  4.5V down to 3.2V

output voltager 4.2V down to 3.2V-Vdropout  (at 200mA)

WIll the device run stable, if Vout<Vin.  ?

I can live with a worse PSRR and that the dropout is current depended.  What will be the rdson?


A: Re: TPS799xx use as a voltage limiter by 10449

The LDO will work well in this application.  That is exactly what it is designed to do.  The output will be stable in dropout (when Vin is less than the programmed Vout voltage)The question about dropout voltage and FET resistance is common so I generated an application note to give a detailed explanation of how to calculate the FET's Rdson and how to calculate the actual dropout voltage at any operating condition for an LDO.  The title is "Undestanding LDO Dropout"  http://focus.ti.com/general/docs/litabsmultiplefilelist.tsp?literatureNumber=slva207