TPS7H1121-SP: PSRR Plot Conditions

Hi Brian,

The data in the PSRR plot shown in Figure 6-21 of the TPS7H1121-SP datasheet was collected with VIN = 5V, VOUT = 3.3V, for a headroom value of 1.7V.

Test condition information for the plots found in the datasheet is also listed at the top of the page, under the "6.7 Typical Characteristics" heading.

PSRR was reported for the TPS7H1121-SP at the listed VIN / VOUT condition across load, so unfortunately there is not a "PSRR vs. Headroom" plot available. 

Thanks,

Andy

Would it be possible to get a plot of PSRR of this regulator operated relatively close to dropout (e.g. 300mV headroom)? It's at best incomplete to show PSRR at 1.7V headroom for something marketed as a low-dropout regulator

Hi Brian,

Yes, I can take a PSRR plot, please provide your operating conditions so I can match them for the measurement.

Per the datasheet specifications, 300mV headroom may put the device into dropout depending on your current level.

Thanks,

Andy

Thanks! So a representative case would be powering a sensitive load with Vin=5.25V, Vout=5V, Iout=250mA. This isn't much headroom but is still well within the max dropout voltage in the datasheet for this case (70mV typ, 100mV max). It would be helpful to see how much the PSRR degrades in this type of tighter headroom scenario.