LP5241
Load switch with programmable slew rate control to limit inrush current during turn-on
Product Overview
Description
The LP5241 is an advanced load switch featuring programmable slew rate control to limit inrush current during turn-on. This feature is essential for powering capacitive loads and preventing voltage droop on the power rail when switching large loads.
The device operates from 1.8V to 5.5V and supports continuous currents up to 1.5A. The on-resistance is 80mΩ typical. An external capacitor connected to the CT pin sets the turn-on slew rate, allowing customization of the turn-on time from microseconds to milliseconds.
The LP5241 includes fault protection features such as over-current protection and thermal shutdown. The active-high enable pin with internal pull-down ensures the switch is off by default. Available in a compact SOT-23-6 package, it is ideal for powering sensitive circuits and large capacitive loads.
Product Series
LP
Primary Application
Capacitive load switching
Key Features
- Programmable slew rate control
- Limits inrush current
- 1.5A continuous current
- 80mΩ on-resistance
- Over-current protection
- Adjustable turn-on time
- Active-high enable
- Thermal shutdown protection
Specifications
| Input Voltage Range | 1.8V - 5.5V |
|---|---|
| Current Rating | 1.5A continuous |
| On-Resistance | 80mΩ typical |
| Quiescent Current | 1μA (disabled) |
| Turn-On Time | Programmable (100μs to 10ms) |
| Turn-Off Time | 10μs typical |
| Slew Rate Control | External capacitor |
| Over-Current Protection | 1.8A typical |
| Operating Temperature | -40°C to +85°C |
| Package | SOT-23-6 |
Applications
Capacitive load switching
Electronic system design
Power sequencing
Electronic system design
Sensitive circuit protection
Electronic system design
Large load switching
Electronic system design
Inrush current limiting
Electronic system design
FAE Expert Insights
"The LP5241 is my go-to load switch when I need to control inrush current. The programmable slew rate is a game-changer - you can set the turn-on time from fast (100μs) to slow (10ms) depending on your load. This is essential when powering circuits with large input capacitors or when you need to prevent voltage droop on a shared power rail. I recently used it in a design powering a WiFi module with 100μF of input capacitance. Without slew rate control, the inrush current caused the system voltage to droop and reset the processor. With LP5241 and a 10nF CT capacitor, the turn-on was smooth and problem-free. The over-current protection is also useful - it limits current to about 1.8A during faults. One implementation tip: the CT capacitor should be a good quality ceramic (X7R) for stable timing. The SOT-23-6 package is still compact but provides the extra pin for CT. Overall, an excellent load switch for applications requiring controlled turn-on."
Load switch with programmable slew rate control for inrush current limiting
— Chen Ming, BeiLuo
Frequently Asked Questions
What is slew rate control and why is it important?
Slew rate control limits how fast the output voltage rises during turn-on. This limits the inrush current when charging capacitive loads, preventing voltage droop on the power rail and avoiding system resets. LP5241 allows programmable slew rate via an external capacitor.
Use slew rate control for capacitive loads >10μF or when sharing power rails; prevents voltage droop.
How do I set the turn-on time of LP5241?
Connect an external capacitor from the CT pin to ground to set the turn-on time. Larger capacitors result in slower turn-on. Typical values range from 100pF (fast turn-on, ~100μs) to 100nF (slow turn-on, ~10ms). The formula is approximately T_ON = CT × 100μs/nF.
Use 100pF-1nF for fast turn-on; 10nF-100nF for slow turn-on with large capacitive loads.
What is the on-resistance of LP5241?
The LP5241 has an on-resistance of 80mΩ typical. While slightly higher than LP5240, this is still excellent for most applications. At 1A current, the voltage drop is 80mV. The slightly higher resistance is due to the additional slew rate control circuitry.
80mΩ on-resistance suitable for most applications; trade-off for slew rate control feature.
Does LP5241 have over-current protection?
Yes, LP5241 includes over-current protection that limits current to approximately 1.8A typical. If the load current exceeds this threshold, the switch limits the current to protect both the switch and the power source. This feature is useful for fault protection.
Over-current protection provides fault tolerance; useful for protecting against short circuits.
When should I use LP5241 vs LP5240?
Use LP5241 when you need to control inrush current for capacitive loads or when powering large loads on shared power rails. Use LP5240 for simple on/off switching where inrush current is not a concern. LP5240 has lower on-resistance (60mΩ vs 80mΩ).
LP5241 for inrush control; LP5240 for simple switching with lower on-resistance.
What capacitive loads require slew rate control?
Consider slew rate control when switching loads with input capacitance greater than 10μF. Large capacitive loads can cause significant inrush current (I = C × dV/dt) and voltage droop. Common examples include powering WiFi modules, motor drivers, or subsystems with bulk capacitance.
Use slew rate control for loads >10μF capacitance; prevents inrush current issues.
What is the disabled current of LP5241?
When disabled, LP5241 draws only 1μA typical current. This low disabled current makes it suitable for battery-powered applications where circuits need to be completely powered down to maximize battery life.
1μA disabled current suitable for battery applications; use for power-gating unused circuits.