Although an input capacitor is not required for stability, good analog design practice is to connect a 0.1-μF to 1-μF low ESR capacitor across the input supply near the regulator. This capacitor counteracts reactive input sources and improve transient response, noise rejection, and ripple rejection. A higher-value capacitor can be necessary if large, fast rise-time load transients are anticipated or the device is located several inches from the power source. If source impedance is not sufficiently low, a 0.1-μF input capacitor can be necessary to ensure stability.

The TPS799-Q1 is designed to be stable with standard ceramic capacitors of values 2.2 μF or larger. X5R and X7R type capacitors are best as they have minimal variation in value and ESR over temperature. Maximum ESR must be <1 Ω.