ZHCSJX4B June 2012 – June 2019 LMR10530
PRODUCTION DATA.
When planning layout there are a few things to consider to achieve a clean, regulated output. The most important consideration is the close coupling of the GND connections of the input capacitor Cin and the catch diode D1. These ground ends should be close to one another and be connected to the GND plane with at least two through-holes. Place these components as close to the IC as possible. The next consideration is the location of the GND connection of the output capacitor Co, which should be near the GND connections of C1 and D1. There must be a continuous ground plane on the bottom layer of a two-layer board except under the switching node island. Tie the signal ground SGND (pin 3) and power ground PGND (pin 6) together and connected to ground plane through vias.
The FB pin is a high impedance node—take care to make the FB trace short to avoid noise pickup that causes inaccurate regulation. The feedback resistors must be placed as close as possible to the IC, with the GND of Rfbb placed as close as possible to the SGND of the IC. Route the VOUT trace to Rfb1 away from the inductor and any other traces that are switching.
High AC currents flow through the VIN, SW, and VOUT traces, so they must be as short and wide as possible. Radiated noise can be decreased by choosing a shielded inductor.
Place the remaining components as close as possible to the IC. See Application Note AN-2280 for further considerations and the LMR10530 demo board as an example of a four-layer layout.