8.1.1 Input and Output Capacitor Requirements

Although an input capacitor is not required for stability on the IN pin, it is good analog design practice to connect a 0.1-μF to 1-μF low equivalent series resistance (ESR) capacitor across the IN pin input supply near the regulator. This capacitor counteracts reactive input sources and improves transient response, noise rejection, and ripple rejection. A higher-value capacitor may be necessary if large, fast rise-time load transients are anticipated, or if the device is located close to the power source. If source impedance is not sufficiently low, a 0.1-μF input capacitor may be necessary to ensure stability.

The BIAS pin does not require an input capacitor because it does not source high currents. However, if source impedance is not sufficiently low, then TI recommends a small 0.1-μF bypass capacitor.

The TPS720 is designed to be stable with standard ceramic capacitors with values of 2.2 μF or larger at the output. X5R- and X7R-type capacitors are best because they have minimal variation in value and ESR over temperature. Maximum ESR should be less than 250 mΩ.