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Semtech Corporation SC4521SETRT-A0
- Part No.:
- SC4521SETRT-A0
- Manufacturer:
- Semtech Corporation
- Package:
- 8-SOIC (0.154", 3.90mm Width) Exposed Pad
- Datasheet:
-
SC4521SETRT-A0.pdf
- Description:
- IC REG BUCK ADJ 3A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,588
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Product details
Overview
SC4521SETRT-A0 from Semtech is a 3A synchronous step-down switching regulator with integrated 3A N-channel MOSFET switch, 600kHz fixed-frequency current-mode control, programmable soft-start via external capacitor, and precision enable threshold (1.72V to 2.15V). It operates from 4.4V to 24V input and delivers regulated output in CPE, XDSL modems, and portable DC-DC point-of-load applications.
For engineers reviewing the SC4521SETRT-A0 datasheet, pinout, applications, or equivalent options, key selection criteria include input voltage range (4.4–24V), peak switch current rating (3A), soft-start timing control (via SS pin capacitor), thermal performance (θJA = 36.5°C/W), and SO-8 EDP package compatibility with high-density PCB layouts.
Technical Context
The SC4521SETRT-A0 implements peak-current-mode control with internal slope compensation, enabling fast transient response and inherent cycle-by-cycle overcurrent protection. Its error amplifier compares FB voltage against 0.8V reference and drives COMP pin to regulate duty cycle.
Startup is managed by a closed-loop soft-start circuit: an internal 100kΩ pull-up to 1.6V and NPN pull-down to GND discharge SS pin during disable/fault; SS voltage ramping controls reference ramp rate until it exceeds 0.8V. The 600kHz oscillator requires no external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.4V to 24V - supports wide-range industrial and telecom inputs without pre-regulation |
| Output Current | Up to 3A continuous - limited by internal switch RDS(on) and thermal design |
| Switching Frequency | 600kHz - enables compact LC filter design with small inductors & ceramics |
| Soft-Start Control | External capacitor on SS pin - sets controlled output voltage ramp time (e.g., 1.5ms with 22nF) |
| Enable Threshold | 1.72V to 2.15V - precise UVLO-based enable logic for reliable system power sequencing |
| Feedback Reference | 0.8V ±1% - high-accuracy reference for stable output regulation across temperature |
| Shutdown Current | 250µA - minimizes battery drain in portable equipment standby mode |
Pinout & Package
SC4521SETRT-A0 is housed in an SO-8 EDP (Enhanced Dissipation Package) with exposed thermal pad, RoHS-compliant and WEEE-compliant. The package supports high-power density designs with low θJA (36.5°C/W) when mounted on 4-layer PCB with thermal vias under the pad.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BST | Bootstrap supply | Provides gate drive voltage ≥2.7V for internal N-channel switch; requires 0.22µF ceramic capacitor to SW |
| IN | Main input supply | Accepts 4.4–24V; connects to input capacitor bank and high-di/dt loop |
| SW | Switch node | Drives external inductor; high dv/dt node requiring tight layout and minimal trace length |
| GND | Power & signal ground | Common return for switch, feedback, and compensation; must connect directly to thermal pad |
| EN | Enable control | Active-high logic input; <0.4V disables regulator and reduces IQ to 250µA |
| FB | Feedback input | Senses output voltage via resistor divider; referenced to 0.8V internal bandgap |
| COMP | Compensation node | Connects external RC network (R3/C4/C5) to stabilize current-mode loop |
| SS | Soft-start timing | Controls startup ramp rate via external capacitor; pulled low during fault or disable |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 3A N-channel switch | Eliminates external MOSFET and driver, reducing BOM count and layout complexity |
| Programmable soft-start | Prevents inrush current and output overshoot with user-defined ramp time via SS capacitor |
| Current-mode control with slope compensation | Enables stable operation at any duty cycle and simplifies loop compensation design |
| Thermal shutdown with hiccup mode | Protects against sustained overload by cycling startup after junction temperature exceeds 150°C |
| UVLO on IN and EN pins | Ensures clean startup only when input and enable conditions meet valid thresholds |
Applications
| XDSL Modems | CPE Equipment |
|---|---|
Use Scenario: Powering DSP, PHY, and memory subsystems in DSL access devices operating from 12–24V wall adapters. IC Role / Device Role / Timing Role: Primary point-of-load buck regulator delivering 3.3V/1A or 1.2V/2A with fast load-step response. Use Value: 600kHz switching enables small 4.7µH inductors and ceramic output caps, meeting space-constrained modem PCB requirements. | Use Scenario: Regulating core voltages for embedded processors and FPGAs in cable modems and residential gateways. IC Role / Device Role / Timing Role: High-efficiency DC-DC converter supporting dynamic voltage scaling and low-noise analog rails. Use Value: Programmable soft-start prevents brownout during cold boot and ensures orderly power-up of multi-rail systems. |
| Portable Equipment | Digital Consumer Electronics |
Use Scenario: Battery-powered test instruments and handheld terminals requiring long runtime and reliable shutdown. IC Role / Device Role / Timing Role: Main system regulator converting Li-ion (8.4–12.6V) or 9V adapter input to 5V/3.3V rails. Use Value: 250µA shutdown current extends battery life; thermal shutdown protects against enclosure overheating. | Use Scenario: Power management in set-top boxes and media streamers with variable input sources (12V/19V adapters). IC Role / Device Role / Timing Role: Secondary buck stage providing isolated, low-noise 1.8V for DDR memory or 1.1V for SoC cores. Use Value: SO-8 EDP package with thermal pad ensures stable operation under full load without heatsink. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2307DN-LF-Z | 3A, 600kHz, but lacks programmable soft-start and has higher shutdown current (100µA vs 250µA) | Less suitable for battery-sensitive portable designs due to missing soft-start control | Choose when cost sensitivity outweighs soft-start requirement and thermal pad is not needed |
| TPS5430DDAR | 3A, adjustable frequency (100–500kHz), but larger SO-8 package without thermal pad and higher θJA (50°C/W) | Requires larger board area and additional thermal relief for same 3A load | Prefer when frequency tuning is required and layout space allows for less efficient thermal path |
Compared with MP2307DN-LF-Z and TPS5430DDAR, the SC4521SETRT-A0 provides superior thermal performance (36.5°C/W), integrated soft-start control, and tighter enable threshold tolerance-making it optimal for space-constrained, thermally demanding CPE and portable applications where startup reliability and efficiency are critical.
Availability
SC4521SETRT-A0 is available at Aetrix Electronics and suitable for XDSL modems, CPE equipment, and portable DC-DC point-of-load applications requiring stable component supply, lead-free compliance, and long-term production continuity.
Supply support for SC4521SETRT-A0 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 SC4521SETRT-A0 belongs to Semtech's Power Management product line, designed specifically for high-efficiency, low-pin-count DC-DC conversion in cost-sensitive, thermally constrained broadband and consumer infrastructure equipment.
FAQ
What is the maximum input voltage rating for the SC4521SETRT-A0?
The SC4521SETRT-A0 has an absolute maximum input voltage rating of 28V, but its specified operating input voltage range is 4.4V to 24V. Operation above 24V risks exceeding internal device stress limits and is not guaranteed per datasheet specifications. For reliable long-term performance, maintain VIN ≤ 24V under all conditions including transients.
How does the soft-start function work on the SC4521SETRT-A0?
The SC4521SETRT-A0 implements closed-loop soft-start using an internal 100kΩ pull-up resistor to a 1.6V reference and an NPN transistor pulling SS to GND during disable or fault. An external capacitor on the SS pin determines ramp time (e.g., TSS ≈ 69,000 × CSS). The regulator begins normal operation only after SS voltage exceeds 0.8V, ensuring controlled output voltage rise and limiting inrush current.
What package type and thermal characteristics does the SC4521SETRT-A0 use?
The SC4521SETRT-A0 uses an SO-8 EDP (Enhanced Dissipation Package) with exposed thermal pad. Its thermal resistance is θJA = 36.5°C/W when mounted on a 4-layer FR4 PCB with thermal vias under the pad per JESD51 standards. This enables reliable 3A operation without external heatsinking in typical CPE and modem applications.
Can the SC4521SETRT-A0 be used in automotive applications?
The SC4521SETRT-A0 is not qualified for automotive applications. Its specified operating junction temperature range is –40°C to +125°C, but it lacks AEC-Q100 qualification, extended temperature screening, or automotive-specific reliability testing. For automotive use, consider Semtech's automotive-grade alternatives or consult manufacturer documentation for qualified equivalents.
What is the purpose of the BST pin on the SC4521SETRT-A0?
The BST pin on the SC4521SETRT-A0 supplies the bootstrap voltage for the internal high-side N-channel MOSFET gate driver. It must be connected to a 0.22µF ceramic capacitor between BST and SW to generate ≥2.7V gate drive, ensuring low RDS(on) and minimal conduction loss. Exceeding the BST-to-SW voltage rating (6.1V max) will damage the device.
SC4521SETRT-A0 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Semtech Corporation
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.4V
- Voltage - Input (Max):
- 24V
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- 24V
- Current - Output:
- 3A
- Frequency - Switching:
- 600kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC, EDP
SC4521SETRT-A0 FAQ
1.How can I place an order for SC4521SETRT-A0 through Aetrix?
Please submit a Request for Quotation (RFQ) for SC4521SETRT-A0 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 SC4521SETRT-A0 reliable?
The price and inventory of SC4521SETRT-A0 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SC4521SETRT-A0 is usually 5 days.
3.What payment methods are accepted for SC4521SETRT-A0?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SC4521SETRT-A0 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SC4521SETRT-A0?
SC4521SETRT-A0 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SC4521SETRT-A0 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 SC4521SETRT-A0?
For technical support, including SC4521SETRT-A0 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SC4521SETRT-A0 requirements.
6.How does Aetrix verify that SC4521SETRT-A0 is sourced from the original manufacturer or authorized distributors?
All SC4521SETRT-A0 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 SC4521SETRT-A0 meets industry standards.
7.What is the process for return or replacement of SC4521SETRT-A0?
All SC4521SETRT-A0 units undergo pre-shipment inspection (PSI). If there is an issue with SC4521SETRT-A0, 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 SC4521SETRT-A0 part is unused and in its original packaging.
Return procedure for SC4521SETRT-A0:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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