ZHCSHI5D March 2001 – February 2018 TPS791
Layout is a critical part of good power-supply design. There are several signal paths that conduct fast-changing currents or voltages that can interact with stray inductance or parasitic capacitance to generate noise or degrade the power-supply performance. To help eliminate these problems, bypass the IN pin to ground with a low ESR ceramic bypass capacitor with an X5R or X7R dielectric.
Equivalent series inductance (ESL) and equivalent series resistance (ESR) must be minimized to maximize performance and ensure stability. Every capacitor (CIN, COUT, CBYPASS, and C1) must be placed as close as possible to the device and on the same side of the PCB as the regulator itself.
Do not place any capacitors on the opposite side of the PCB from where the regulator is installed. The use of vias and long traces is strongly discouraged because these circuits can impact system performance negatively, and even cause instability.