Power management
Power Switch / Load Switch (PSW)
Integrated MOSFET switches with controlled turn-on, soft-start, and protection.
What is it?
A load switch is a packaged MOSFET with built-in gate driver, controlled slew rate, optional soft-start, and integrated protections (over-current, thermal). Used to gate a power rail on or off in response to a logic signal — far cleaner than driving a discrete MOSFET yourself. Modern parts include features like reverse-current blocking and quick output discharge.
When do you need it?
- Switching individual sub-system rails on/off for power gating (idle modes).
- Sequencing one rail after another (with controlled inrush).
- Hot-swap or insertion protection (controlled rise time prevents giant inrush).
- Over-current and thermal protection without external monitor circuits.
- USB host port enable/disable with current limit.
How to pick the right one
- VIN range
- Must span your gated rail (1.5-5.5 V for low-voltage, up to 24 V for industrial).
- IOUT (continuous current)
- Match to load. 1 A / 3 A / 6 A common. Check Tj rise at full current.
- RDS(on)
- Lower = less voltage drop and self-heating. Modern PSWs are 10-50 mΩ.
- Soft-start time
- Controls inrush. Useful for capacitive loads; pick longer for larger output cap.
- Protection features
- Over-current threshold, thermal trip, reverse-current blocking, auto-discharge — pick the set matching your fault-handling design.
- Channels
- Single-channel for one rail; dual-channel for two independent rails in one package.
What Magnias offers
Magnias active PSW family: PSW5192 (3 A, single, CSP1010), PSW2892-F21 (6 A, single, DFN2020), PSW2898-F23 (6 A, dual-channel, TDFN2x3), PSW529-TF2 (6 A, single, TDFN2x2). Earlier PSW0134 / 0567 / 0529 / 1810 are EOL — please standardise on the current parts.
Common questions
Load switch or discrete MOSFET?
Load switch wins for: simplicity (no separate gate driver), built-in soft-start, integrated protection. Discrete MOSFET wins for: lowest cost at high volume, custom slew control, very high current (>10 A).
What's auto-discharge?
When the switch turns off, an internal resistor pulls the output to ground quickly. Prevents downstream rail from floating with residual charge.
Does the load switch protect against reverse current?
Some do (reverse-current blocking), some don't. If your load can back-feed (e.g., a battery in parallel with USB), pick a part with explicit reverse-blocking.