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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear Regulator Controllers

Semtech Corporation SC1548CSK.TR

Name: SC1548CSK.TR
Brand: Semtech Corporation
SKU: SC1548CSK.TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SC1548CSK.TR

Manufacturer:: Semtech Corporation

Category:: Voltage Regulators - Linear Regulator Controllers

Package:: SC-74A, SOT-753

Datasheet:: SC1548CSK.TR.pdf

Description:: IC REGULATOR CONTROLLER SOT23

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Product details

Overview

SC1548CSK.TR from Semtech is a linear FET controller IC designed to drive external N-channel MOSFETs for tightly regulated low-voltage power supplies. It delivers 1.818V output for I/O planes or 1.515V for GTL+/AGP from 3.3V/2.5V inputs, features ±2.5% output accuracy over line/load/temperature, enable control, and overcurrent protection with 50% V_OUT trip threshold and ~4ms shutdown delay. Used in motherboard and graphics card power rails.

For engineers reviewing the SC1548CSK.TR datasheet, pinout, applications, or equivalent options, key selection criteria include fixed/adjustable output voltage options (1.515V, 1.818V, or 1.263–5V), SOT-23-5 package constraints, sense-pin-based OCP timing, drive pin voltage capability (≥9V), and thermal derating in high-power linear regulator configurations.

Technical Context

The SC1548CSK.TR implements a bandgap-referenced error amplifier controlling an external N-channel MOSFET via its DRV pin. Regulation is achieved by comparing feedback from either internal resistor dividers (fixed versions) or external ADJ/SNS network to a 1.263V reference. Output voltage is set by resistor ratio, not DAC or digital interface.

OCP operates by monitoring output voltage collapse: when V_OUT drops below ~50% of nominal for >4ms, the controller latches DRV low. Enable logic is active-high with internal pull-up; disable occurs at V_EN < 1.83V (typ), with 200mV hysteresis. Thermal shutdown is not integrated - dissipation is managed externally via MOSFET selection and PCB layout.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 1.818V (SC1548CSK-1.8) - precise for AGP/I/O plane biasing per JEDEC GTL+ spec.
Output Accuracy	±2.5% over line, load, and temperature - ensures stable logic-level compliance across operating conditions.
OCP Threshold	V_OUT < 50% nominal for >4ms - avoids false trips during capacitor inrush while protecting against sustained shorts.
DRV Pin Voltage	≥9V guaranteed min - enables use of higher-V_GS MOSFETs for lower R_DS(on) and improved efficiency.
Enable Threshold	V_EN(H) = 2.3V (min), V_EN(L) = 1.83V (max) - supports direct interfacing with 3.3V/2.5V logic without level shifters.
Quiescent Current	150µA (typ) - minimizes standby power loss in always-on supply rails.
Package	SOT-23-5 - surface-mount footprint compatible with high-density PCB layouts on motherboards and graphics cards.

Pinout & Package

The SC1548CSK.TR is housed in a 5-pin SOT-23-5L package with exposed pad (not electrically connected). Pin 1 is SNS/ADJ (sense or adjust input), Pin 2 is GND (power ground reference), Pin 3 is DRV (MOSFET gate drive output), Pin 4 is IN (12V supply input), and Pin 5 is EN (active-high enable with internal pull-up).

Pin/Terminal	Circuit Role	Design Meaning
1 (SNS/ADJ)	Sense or Adjust input	For fixed versions: SNS sinks 100µA - connects to output node for regulation; for adjustable version: ADJ sources 0.5µA - connects to resistor divider top node.
2 (GND)	Power ground reference	Must connect directly to low-impedance ground plane to avoid regulation error from IR drop.
3 (DRV)	MOSFET gate driver output	Drives external N-MOSFET gate; capable of ≥9V swing - requires external gate resistor for ringing control.
4 (IN)	12V supply input	Powers internal circuitry; bypassed with 0.1µF ceramic capacitor placed near pin to suppress switching noise.
5 (EN)	Active-high enable input	Internal 100kΩ pull-up to VPWR; pulled low to disable DRV - no external pull-down required unless system demands explicit control.

Key Features

Feature	Design Value
Tight output regulation	±2.5% accuracy over full temp/load/line range - eliminates need for post-regulation trimming in cost-sensitive computing power rails.
Integrated OCP with latch-off	Auto-shutdown on sustained overcurrent; reset via EN toggle or power cycle - prevents MOSFET thermal runaway without external circuitry.
Flexible output configuration	Fixed 1.515V/1.818V or adjustable 1.263–5V via external resistors - supports multiple voltage domains from single BOM part.
Low quiescent current	150µA typical - reduces idle power in systems requiring always-on auxiliary rails.
Robust enable interface	Internal pull-up + 200mV hysteresis - tolerates slow-rising or noisy enable signals in complex motherboard power sequencing.

Applications

Graphics Card Power Rail	Motherboard I/O Plane Supply
Use Scenario: Providing stable 1.818V to GPU I/O buffers and memory interfaces on PCIe graphics cards. IC Role / Device Role / Timing Role: Linear FET controller regulating output via external MOSFET; sets precise voltage using internal 1.818V divider. Use Value: Meets GTL+ bus voltage tolerance (±2.5%) without external feedback components, reducing BOM count and layout area.	Use Scenario: Generating 1.515V for chipset I/O on ATX motherboards with multi-rail power architecture. IC Role / Device Role / Timing Role: Fixed-output linear controller driving discrete N-MOSFET; enables clean power sequencing with enable pin coordination. Use Value: Eliminates need for dedicated LDO ICs - leverages existing 12V rail and low-cost MOSFETs for cost-optimized design.
Adjustable Core Bias Supply	Embedded Microcontroller Auxiliary Rail
Use Scenario: Configurable 2.5V/3.3V supply for FPGA core or analog subsystems where voltage margining is required. IC Role / Device Role / Timing Role: Adjustable linear controller using external R1/R2 divider on ADJ pin; supports 1.263–5V range. Use Value: Single part replaces multiple fixed-LDO SKUs - simplifies inventory and enables field-programmable voltage tuning via resistor change.	Use Scenario: Low-noise 3.0V auxiliary rail for microcontroller peripherals (ADC, USB PHY) in industrial controllers. IC Role / Device Role / Timing Role: Linear regulator controller with enable pin synchronized to MCU wake-up signal. Use Value: Enables zero-quiescent-current sleep mode via EN pin; 150µA IQ minimizes battery drain in always-on monitoring applications.

Graphics Card Power Rail

Motherboard I/O Plane Supply

Use Scenario: Providing stable 1.818V to GPU I/O buffers and memory interfaces on PCIe graphics cards.

IC Role / Device Role / Timing Role: Linear FET controller regulating output via external MOSFET; sets precise voltage using internal 1.818V divider.

Use Value: Meets GTL+ bus voltage tolerance (±2.5%) without external feedback components, reducing BOM count and layout area.

Use Scenario: Generating 1.515V for chipset I/O on ATX motherboards with multi-rail power architecture.

IC Role / Device Role / Timing Role: Fixed-output linear controller driving discrete N-MOSFET; enables clean power sequencing with enable pin coordination.

Use Value: Eliminates need for dedicated LDO ICs - leverages existing 12V rail and low-cost MOSFETs for cost-optimized design.

Adjustable Core Bias Supply

Embedded Microcontroller Auxiliary Rail

Use Scenario: Configurable 2.5V/3.3V supply for FPGA core or analog subsystems where voltage margining is required.

IC Role / Device Role / Timing Role: Adjustable linear controller using external R1/R2 divider on ADJ pin; supports 1.263–5V range.

Use Value: Single part replaces multiple fixed-LDO SKUs - simplifies inventory and enables field-programmable voltage tuning via resistor change.

Use Scenario: Low-noise 3.0V auxiliary rail for microcontroller peripherals (ADC, USB PHY) in industrial controllers.

IC Role / Device Role / Timing Role: Linear regulator controller with enable pin synchronized to MCU wake-up signal.

Use Value: Enables zero-quiescent-current sleep mode via EN pin; 150µA IQ minimizes battery drain in always-on monitoring applications.

Equivalent & Alternatives

The following parts are listed as comparable options for similar linear FET controller applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM317LZ/NOPB	Adjustable 1.25V reference; no integrated enable or OCP; requires external pass transistor.	Lacks latch-off OCP and active-high enable - needs discrete logic for sequencing and protection.	Choose LM317LZ/NOPB only if cost is primary constraint and system-level OCP/enable is already implemented elsewhere.
TPS7A4700RGWR	Ultra-low-noise LDO (4µV_RMS); fixed/adjustable; integrated thermal/overcurrent protection; no external FET drive.	Monolithic LDO - cannot scale to high-current (>1A) linear regulation without excessive die heating.	Choose TPS7A4700RGWR for noise-sensitive analog rails ≤500mA; SC1548CSK.TR remains preferred for >1A I/O rail regulation with external MOSFET thermal management.

Compared with LM317LZ/NOPB, SC1548CSK.TR integrates enable and latch-off OCP, reducing external component count; compared with TPS7A4700RGWR, it supports higher output current via external MOSFET but requires careful thermal design and external protection coordination.

Availability

SC1548CSK.TR is available at Aetrix Electronics and suitable for motherboard power delivery, graphics card I/O regulation, and embedded microcontroller auxiliary rails requiring stable component supply with RoHS-compliant packaging and tape-and-reel logistics.

Supply support for SC1548CSK.TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Semtech Corporation is a U.S.-based semiconductor company specializing in high-performance analog and mixed-signal ICs for power management, RF, and sensing applications.

The SC1548CSK.TR belongs to Semtech's SmartLDO™ family, engineered specifically for simple, low-cost linear regulation in computing infrastructure where precision, enable control, and robust overcurrent response are critical.

FAQ

What output voltage does the SC1548CSK.TR deliver?

The SC1548CSK.TR is the 1.818V fixed-output variant of the SC1548 family. It delivers precisely 1.818V for GTL+/AGP I/O plane applications, with ±2.5% accuracy across line, load, and temperature. This value is set by internal resistor dividers - no external components are needed for basic operation. The SC1548CSK.TR pinout places the SNS pin (Pin 1) directly on the output node for closed-loop regulation.

How does overcurrent protection work in the SC1548CSK.TR?

The SC1548CSK.TR implements overcurrent protection by continuously monitoring output voltage. If V_OUT falls below ~50% of nominal (i.e., <0.909V for SC1548CSK.TR) for longer than ~4ms, the device latches DRV low, disabling the external MOSFET. Recovery requires toggling EN or cycling VIN. This method relies on MOSFET R_DS(on) saturation - no current-sense resistor is needed. The SC1548CSK.TR datasheet specifies this behavior under Electrical Characteristics, Table "Overcurrent Protection".

Can the SC1548CSK.TR be used with a 2.5V input supply?

No - the SC1548CSK.TR requires a 12V supply on its IN pin (Pin 4) to power internal circuitry and generate sufficient gate drive voltage. Its input voltage specification is 12V (absolute max 15V), not 2.5V or 3.3V. However, the *output* can be derived from lower intermediate rails (e.g., 3.3V or 2.5V) using an external buck converter feeding the 12V input stage. The SC1548CSK.TR itself does not accept sub-10V inputs.

What is the function of the SNS pin on the SC1548CSK.TR?

On the SC1548CSK.TR, Pin 1 is the SNS (Sense) pin, which connects directly to the regulated output node. It sinks a nominal 100µA current and feeds the error amplifier's inverting input. The internal 1.263V bandgap reference is compared against the voltage at this node to maintain regulation. For SC1548CSK.TR, no external resistors are needed - the SNS connection completes the feedback loop. Incorrect routing (e.g., long traces, shared ground) introduces regulation error, so direct low-impedance connection is mandatory.

Is the SC1548CSK.TR RoHS compliant and lead-free?

Yes, the SC1548CSK.TR is fully RoHS compliant and lead-free, as confirmed in the official Semtech datasheet (Revision November 10, 2004, page 5, Note 3). It meets WEEE requirements and is supplied in tape-and-reel packaging (3000 units per reel). No lead-containing solder or finishes are used in its SOT-23-5L package. This compliance applies to the SC1548CSK.TR manufacturing lot and is documented in Semtech's material declarations.

SC1548CSK.TR Specifications

Product attributes: Attribute value

Manufacturer:: Semtech Corporation

Series:: SmartLDO™

Package/Case:: SC-74A, SOT-753

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: Positive Adjustable

Number of Outputs:: 1

Current - Supply:: 1mA

Voltage - Input:: 11.28V ~ 12.72V

Operating Temperature:: 0°C ~ 70°C (TA)

Mounting Type:: Surface Mount

Supplier Device Package:: SOT-23-5

SC1548CSK.TR FAQ

1.How can I place an order for SC1548CSK.TR through Aetrix?

Please submit a Request for Quotation (RFQ) for SC1548CSK.TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SC1548CSK.TR reliable?

The price and inventory of SC1548CSK.TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SC1548CSK.TR is usually 5 days.

3.What payment methods are accepted for SC1548CSK.TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SC1548CSK.TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SC1548CSK.TR?

SC1548CSK.TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SC1548CSK.TR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SC1548CSK.TR?

For technical support, including SC1548CSK.TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SC1548CSK.TR requirements.

6.How does Aetrix verify that SC1548CSK.TR is sourced from the original manufacturer or authorized distributors?

All SC1548CSK.TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SC1548CSK.TR meets industry standards.

7.What is the process for return or replacement of SC1548CSK.TR?

All SC1548CSK.TR units undergo pre-shipment inspection (PSI). If there is an issue with SC1548CSK.TR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SC1548CSK.TR part is unused and in its original packaging.

Return procedure for SC1548CSK.TR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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