11.1 Layout Guidelines

To improve the switching characteristics and efficiency of a design, the following layout rules should be followed.

• Locate the driver as close as possible to the MOSFETs.
• Locate the V_DD-V_SS and V_HB-V_HS (bootstrap) capacitors as close as possible to the device (see Figure 24).
• Pay close attention to the GND trace. Use the thermal pad of the DDA and DRM package as GND by connecting it to the VSS pin (GND). The GND trace from the driver goes directly to the source of the MOSFET but should not be in the high current path of the MOSFET(S) drain or source current.
• Use similar rules for the HS node as for GND for the high-side driver.
• For systems using multiple UCC27210 and UCC27211 devices we recommend that dedicated decoupling capacitors be located at V_DD-V_SS for each device.
• Care should be taken to avoid VDD traces being close to LO, HS, and HO signals.
• Use wide traces for LO and HO closely following the associated GND or HS traces. 60 to 100-mils width is preferable where possible.
• Use as least two or more vias if the driver outputs or SW node must be routed from one layer to another. For GND the number of vias must be a consideration of the thermal pad requirements as well as parasitic inductance.
• Avoid LI and HI (driver input) going close to the HS node or any other high dV/dT traces that can induce significant noise into the relatively high impedance leads.

Keep in mind that a poor layout can cause a significant drop in efficiency or system malfunction versus a good PCB layout and can even lead to decreased reliability of the whole system.

11.2 Layout Example

Figure 24. UCC27210/11 Component Placement

11.3 Thermal Considerations

The useful range of a driver is greatly affected by the drive-power requirements of the load and the thermal characteristics of the package. In order for a gate driver to be useful over a particular temperature range the package must allow for the efficient removal of the heat produced while keeping the junction temperature within rated limits. The thermal metrics for the driver package is listed in Device Functional Modes. For detailed information regarding the table, please refer to the Application Note from Texas Instruments entitled IC Package Thermal Metrics (SPRA953). The UCC27210 and UCC27211 devices are offered in SOIC (8), PowerPad (8), WSON (10) or VSON (8). The Thermal Information section lists the thermal performance metrics related to SOT-23 package.