12.1 Layout Guidelines

The TPS2475x applications require careful attention to layout to ensure proper performance and to minimize susceptibility to transients and noise. In general, all traces must be as short as possible, but the following list deserves first consideration:

• Decoupling capacitors on VCC pin must have minimal trace lengths to the pin and to GND.
• Traces to SET and SENSE must be short and run side-by-side to maximize common-mode rejection. Kelvin connections must be used at the points of contact with R_SENSE. See Figure 51 and Figure 52 for a PCB layout example.
• SET runs must be short on both sides of R_SET.
• High current carrying Power path connections must be as short as possible and sized to carry at least twice the full-load current, more if possible.
• Connections to IMON pin must be minimized after the previously described connections have been placed.
• The reference must should be a copper plane or island. Use via holes if necessary for direct connections of components to their appropriate return ground plane or island.
• Thermal Considerations: When properly mounted the PowerPAD package provides significantly greater cooling ability than an ordinary package. To operate at rated power, PowerPAD-2 must be soldered directly to the PC board DRAIN plane directly under the device. The PowerPAD-2 is at the DRAIN potential and can be connected using multiple vias to the inner and bottom layers of the DRAIN. The bottom side of the circuit board is highly recommended to be used for DRAIN plane to increase heat sinking in higher current applications. Refer to Technical Briefs: PowerPAD^TM Thermally Enhanced Package, SLMA002) and PowerPAD™ Made Easy, SLMA004) for more information on using this PowerPad package.
• The thermal via land pattern specific to the TPS2475x can be downloaded from the device webpage.
• Protection devices such as snubbers, TVS, capacitors, or diodes must be placed physically close to the device they are intended to protect, and routed with short traces to reduce inductance. For example, the protection Schottky diode suggested to address transients due to heavy inductive loads, must be physically close to the OUT pins.