SC1548CSK.TR

Overview

The SC1548CSK.TR is a linear FET controller from Semtech’s SmartLDO family, designed to drive an external N-channel MOSFET for regulated power supply generation. It operates from a 12V input and accepts a 2.5V to 3.6V power supply (VPWR). The device provides fixed output options of 1.515V or 1.818V, with an adjustable version supporting voltages from 1.263V up to 5V. It features ±2.5% output accuracy over line, load, and temperature ranges, along with active high enable control and overcurrent protection that latches off if the output drops below 50% of nominal.

Feature Summary

• Provides tight output voltage regulation with ±2.5% accuracy across line, load, and temperature variations.
• Includes active high enable control with internal pullup resistor for simple system integration.
• Features overcurrent protection that monitors output voltage and latches off if it falls below 50% of nominal.
• Supports fixed 1.515V and 1.818V outputs or user-defined adjustable voltages via external resistors.

Applications

• Motherboards
• Graphics cards
• Microcontrollers
• Simple power supplies

Procurement Notes

Verify component authenticity through authorized distributors or direct manufacturer channels. Confirm package type matches SOT-23-5 specifications. Check datasheet revisions for any updates to electrical characteristics or pin configurations. Ensure handling precautions are followed due to ESD sensitivity. Validate ordering suffixes against official Semtech documentation to confirm exact voltage options and packaging details.

Selection Notes

Select the appropriate voltage option based on target application requirements: 1.515V for GTL+/AGP, 1.818V for I/O planes, or the adjustable version for custom voltages between 1.263V and 5V. Ensure the external N-channel MOSFET selected has a low enough RDS(ON) to support the required current while allowing proper overcurrent detection. Verify input voltage compatibility with the 12V IN and VPWR pins. Consider thermal management needs based on power dissipation calculations.

Part Context

The SC1548 belongs to Semtech's SmartLDO family of power management ICs. It is part of a broader portfolio including other linear regulators and controllers designed for computer and peripheral applications. This specific model is optimized for driving external MOSFETs to create efficient, regulated power rails in space-constrained environments using the compact SOT-23-5 package.

Replacement Considerations

Direct replacements may include other SC1548 variants with different fixed output voltages (e.g., SC1548CSK-1.8TRT for 1.818V). For adjustable versions, ensure the replacement supports the same voltage range and pinout. Cross-reference with similar linear FET controllers from other manufacturers only if pin compatibility and electrical parameters match exactly.

FAQ

How does the overcurrent protection work?

The SC1548 monitors the output voltage. If the output drops below approximately 50% of its nominal value, indicating an overcurrent or short circuit condition, the device pulls the drive pin low and latches off. The latch can be reset by toggling the enable pin or cycling the power.

Can the fixed output voltage versions be adjusted?

Yes, the fixed output versions (1.515V and 1.818V) can be adjusted upwards by applying an external resistor divider to the sense pin. The adjustment must ensure sufficient current flows through the divider to maintain regulation accuracy.

What is the purpose of the VPWR pin?

The VPWR pin supplies power to the internal control circuitry. It typically connects to a 2.5V, 3.3V, or 5V rail, separate from the main 12V input used for driving the external MOSFET.