10 Power Supply Recommendations

The maximum IC junction temperature should be restricted to 150°C under normal operating conditions. This restriction limits the power dissipation of the TPS55340-EP. The TPS55340-EP features a thermally-enhanced WQFN package. This package includes a PowerPAD that improves the thermal capabilities of the package. The thermal resistance of the WQFN package in any application greatly depends on the PCB layout and the PowerPAD connection. The PowerPAD must be soldered to the analog ground on the PCB. Use thermal vias underneath the PowerPAD to achieve good thermal performance.

V_IN = 24 V

Figure 10-1 Power Dissipation of TPS55340-EP

T_A = Room temperature		V_IN = 24 V
V_OUT to V_{SW_in} = 5 V/0 A		I_{SW_OUT1/2} = 1.2 A
EVM board: 4-layer PCB, 1.6-mm thickness, 2-oz. copper thickness, 65-mm × 65-mm size, 25 vias at thermal pad

Figure 10-3 Thermal Signature of TPS55340EVM

V_IN = 12 V

Figure 10-2 Power Dissipation of TPS55340-EP

T_A = Room temperature		V_IN = 24 V
V_OUT = 5 V/4 A		I_{SW_OUT1/2} = 0 A
EVM board: 4-layer PCB, 1.6-mm thickness, 2-oz. copper thickness, 65-mm × 65-mm size, 25 vias at thermal pad

Figure 10-4 Thermal Signature of TPS55340EVM