Lowpowersemi Load Switches

Use a load switch when you need simple on/off control of a power rail without voltage conversion. Load switches are simpler, lower cost, and generate no noise. Use a DC-DC converter when you need to step up or step down voltage, or when high efficiency is required for voltage conversion.

Load switch for simple on/off control; DC-DC for voltage conversion or high efficiency.

On-resistance (Rds(on)) is the resistance of the switch when turned on. Lower on-resistance means less voltage drop and power loss (P = I² × R). For example, at 1A current, 60mΩ causes 60mV drop and 60mW loss. Choose lower on-resistance for higher current applications.

Lower on-resistance better for high currents; calculate voltage drop and power loss for your application.

Inrush current is the surge of current when charging capacitive loads during turn-on. It can be calculated as I = C × dV/dt. Control it using slew rate limiting (LP5241), which slows the voltage rise and reduces peak current. This prevents voltage droop on shared power rails.

Use slew rate control for capacitive loads; LP5241 programmable slew rate ideal for this purpose.

Power dissipation in a load switch is calculated as P = I² × Rds(on), where I is the load current and Rds(on) is the on-resistance. For example, with 1A current and 60mΩ on-resistance, dissipation is 60mW. Ensure this is within the thermal capabilities of your package and PCB.

Calculate P = I² × R; verify thermal design can handle dissipation at max current.

Paralleling load switches is generally not recommended due to potential current imbalance. Instead, select a load switch with higher current rating or use a DC-DC converter for high-current applications. If paralleling is necessary, ensure careful PCB layout for current sharing.

Avoid paralleling; select higher current rated switch or use DC-DC converter instead.