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onsemi FAN21SV04EMPX
- Part No.:
- FAN21SV04EMPX
- Manufacturer:
- onsemi
- Package:
- 25-WQFN Exposed Pad
- Datasheet:
-
FAN21SV04EMPX.pdf
- Description:
- IC REG BUCK ADJ 4A 25MLP
- Quantity:
- Payment:
- Shipping:
Inventory:2,495
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Product details
Overview
FAN21SV04EMPX from ON Semiconductor is a fully integrated synchronous buck regulator delivering 4 A output current with 0.8 V to 80% VIN adjustable output voltage, operating from 3.0 V to 24 V input, housed in a 5 × 6 mm, 25-pin MLP package, and used for point-of-load regulation in telecom and computing systems.
For engineers reviewing the FAN21SV04EMPX datasheet, pinout, applications, or equivalent options, key selection considerations include its -40°C to +85°C operating range, programmable 200–600 kHz switching frequency, integrated bootstrap diode, external compensation capability, and power-good signaling for system sequencing and fault monitoring.
Technical Context
The FAN21SV04EMPX implements summing-mode PWM control with cycle-by-cycle current limiting, using an internal ramp generator whose amplitude is set by RRAMP and modulated by VIN for feedforward stability. It integrates high- and low-side MOSFETs with optimized interconnects and an onboard 5 V regulator enabling single-supply operation above 6.5 V.
Its dual-mode clock interface supports master (CLK output, 180° phase shift) or slave (CLK input, synchronizable to external system clock) configurations. Soft-start is digitally controlled, releasing protection circuits only after SS reaches 1.0 V, while pre-bias startup prevents output discharge during initial power-up.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 4 A continuous - supports high-current point-of-load rails without external MOSFETs. |
| Input Voltage Range | 3.0 V to 24 V - enables single-input operation across wide industrial and telecom supply rails. |
| Output Voltage Range | 0.8 V to 80% VIN - allows precise low-voltage core supplies (e.g., 1.2 V, 1.8 V, 3.3 V) with adaptive headroom. |
| Switching Frequency | 200–600 kHz programmable - balances efficiency, size, and EMI; supports all-ceramic output filtering. |
| Reference Accuracy | ±1% over temperature - ensures tight output regulation critical for CPU/GPU core supplies. |
| Peak Efficiency | >94% - minimizes thermal load and improves power density in space-constrained modules. |
| Operating Temperature | -40°C to +85°C - qualified for extended industrial and telecom base station environments. |
| Package | 5 × 6 mm, 25-pin MLP with 3 thermal pads - provides low θJC (4–7°C/W) and high power dissipation (2.8 W at TA=25°C). |
Pinout & Package
Package: Molded Leadless Package (MLP), 5 mm × 6 mm, 25-pin with three exposed thermal pads (P1, P2, P3) on bottom surface for enhanced heat transfer.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (P1, P6–P12) | Switching Node | Junction of internal high- and low-side MOSFETs; connects to inductor and boot capacitor - critical for layout low-inductance loop. |
| VIN (P2, P3–P5) | Main Input Power | Primary power input for conversion stage; accepts 3.0–24 V; multiple pins reduce IR drop and improve current sharing. |
| PGND (P3, P21–P23) | Power Ground | Return path for low-side MOSFET source and output capacitor; separate from AGND to minimize noise coupling. |
| BOOT (Pin 1) | High-Side Gate Drive Supply | Connects via capacitor to SW; internal synchronous bootstrap diode recharges it to 5 V_Reg - eliminates external diode. |
| PGOOD (Pin 13) | Power-Good Signal | Open-drain output asserting LOW when FB deviates >±10% from reference; delays HIGH assertion until soft-start completes. |
| EN (Pin 14) | Enable Control | Logic-high enable with internal 800 kΩ pull-up; toggling resets latched faults; sinks 1 µA during auto-restart. |
| 5V_Reg (Pin 15) | Internal Regulator Output | 5.0 V ±3% regulated supply powering internal logic, drivers, and external bias - capable of sourcing 5 mA. |
| FB (Pin 19) | Feedback Input | Monitors output via resistor divider; referenced to 0.8 V internal bandgap - sets output voltage with ±1% accuracy. |
| COMP (Pin 20) | Compensation Node | Error amplifier output; connects external RC network to FB for loop stability tuning - enables flexible dynamic response. |
| CLK (Pin 24) | Master/Slave Clock Interface | Bidirectional: outputs synchronized clock (180° phase) in master mode; accepts external clock in slave mode. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Synchronous MOSFETs | Eliminates external high- and low-side switches, reducing BOM count and PCB area while optimizing gate drive timing. |
| Programmable Over-Current Protection | RILIM resistor sets current-limit threshold below default 6.5 A - enables precise fault margining for different inductor/PCB layouts. |
| Start-Up on Pre-Biased Outputs | Prevents reverse current flow into powered loads during hot-insertion or multi-rail sequencing - avoids bus contention. |
| External Compensation | Allows full control over loop bandwidth, phase margin, and transient response - essential for varying load conditions and output caps. |
| Thermal Shutdown with Hysteresis | Shuts down at 155°C junction temperature and restarts at 125°C - prevents thermal runaway while enabling safe recovery. |
| Single-Supply Operation (>6.5 V) | Onboard 5 V regulator powers internal circuitry directly from VIN - removes need for auxiliary bias supply in most applications. |
Applications
| Server VR12 Core Supply | Telecom Line Card POL |
|---|---|
|
Use Scenario: Provides 1.2 V @ 4 A to FPGA or ASIC cores on high-density server motherboards with strict thermal and space constraints. IC Role / Device Role / Timing Role: Primary point-of-load buck regulator managing dynamic load transients and sequencing with PGOOD handshake. Use Value: Integrated MOSFETs and 5 × 6 mm MLP package reduce solution footprint by >40% vs. discrete controllers; 94% peak efficiency lowers cooling requirements. |
Use Scenario: Powers DSPs and SerDes on telecom line cards requiring stable 3.3 V output across -40°C to +85°C ambient. IC Role / Device Role / Timing Role: Synchronized POL regulator slaved to system clock to minimize beat-frequency EMI in dense backplane environments. Use Value: Master/slave CLK interface enables deterministic switching alignment; ±1% reference ensures compliance with tight DSP supply tolerances. |
| Graphics Card Memory Rail | Gaming Console SoC Core Supply |
|
Use Scenario: Delivers 1.8 V @ 4 A to GDDR6 memory subsystems with fast load-step response and minimal voltage droop. IC Role / Device Role / Timing Role: High-bandwidth synchronous buck converter with external compensation tuned for ceramic-cap-dominated output filters. Use Value: Programmable 200–600 kHz frequency allows optimization for low EMI (300 kHz) or small inductors (600 kHz); pre-bias startup supports hot-plug memory modules. |
Use Scenario: Supplies 1.05 V core voltage to application processors in consumer gaming consoles with aggressive thermal limits. IC Role / Device Role / Timing Role: Compact, thermally robust POL regulator leveraging MLP package's low θJC for direct heatsink mounting. Use Value: 2.8 W power dissipation rating at 25°C ambient and integrated thermal shutdown ensure reliable operation under sustained 4 A loads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2451DT-LF-Z | 3 A rated, 4.5–26 V input, fixed 500 kHz, no PGOOD or sync capability, SOIC-8 package. | Lacks master/slave synchronization, power-good signaling, and programmable frequency - suitable only for simpler, non-critical rails. | Select when cost and board space are primary concerns and system-level timing coordination is unnecessary. |
| TPS544B25RTER | 4 A, 4.5–18 V input, 400–2000 kHz, PMBus interface, 4 × 4 mm QFN, integrated MOSFETs, but requires external VDD bias. | Supports digital telemetry and dynamic voltage scaling via PMBus - adds complexity but enables real-time monitoring. | Choose when telemetry, remote configuration, or adaptive voltage scaling are required; not drop-in compatible due to bias and protocol differences. |
Compared with MP2451DT-LF-Z and TPS544B25RTER, the FAN21SV04EMPX uniquely combines wide 3–24 V input, -40°C to +85°C rating, master/slave clock sync, and integrated bootstrap diode in a thermally optimized MLP - making it optimal for high-reliability, space-constrained POL designs where analog flexibility and robust fault management are essential.
Availability
FAN21SV04EMPX is available at Aetrix Electronics and suitable for telecom infrastructure, server power delivery, and embedded computing applications requiring stable component supply, long-term lifecycle support, and guaranteed industrial temperature performance.
Supply support for FAN21SV04EMPX 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
ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.
The FAN21SV04EMPX belongs to the TinyBuck™ family of integrated synchronous buck regulators, designed specifically for compact, high-efficiency point-of-load conversion in space- and thermal-constrained systems such as servers, graphics cards, and telecom equipment.
FAQ
What is the operating temperature range of the FAN21SV04EMPX?
The FAN21SV04EMPX is rated for -40°C to +85°C ambient operating temperature, as confirmed in the Ordering Information table and Recommended Operating Conditions section of the datasheet. This extended industrial range distinguishes it from the standard FAN21SV04MPX (-10°C to +85°C) and makes it suitable for base station, outdoor telecom, and ruggedized computing applications where thermal margins are critical. The FAN21SV04EMPX maintains full electrical specifications across this range.
Does the FAN21SV04EMPX require an external bootstrap diode?
No, the FAN21SV04EMPX integrates a synchronous bootstrap diode on-chip, as explicitly stated in the Features list and Pin Definitions (Pin 1 BOOT description). This eliminates the need for an external discrete diode, simplifying layout and improving reliability. The internal diode recharges the BOOT capacitor to the 5 V_Reg rail when the SW node is low, supporting high-side gate drive without added components.
How is the switching frequency programmed on the FAN21SV04EMPX?
The FAN21SV04EMPX switching frequency is set via an external resistor (RT) connected from Pin 18 (RT) to AGND in master mode, yielding 200–600 kHz per the Electrical Characteristics table. In slave mode, RT is tied to 5 V_Reg through a resistor to configure CLK as input. Frequency vs. RT curves (Figure 6) and test data (e.g., RT = 24 kΩ → 600 kHz) confirm this programmability. The FAN21SV04EMPX does not support voltage-controlled or digital frequency setting.
Can the FAN21SV04EMPX start up when the output is already biased?
Yes, the FAN21SV04EMPX supports startup on pre-biased outputs, as documented in the "Startup on Pre-Bias" section and Figure 26. It inhibits low-side MOSFET conduction until the soft-start ramp reaches ~95% of VREF (~0.76 V), preventing reverse current flow and output discharge. This feature is essential for hot-swap, multi-rail, and modular power systems where downstream circuitry may be powered before the FAN21SV04EMPX enables.
What protections are built into the FAN21SV04EMPX?
The FAN21SV04EMPX includes over-current protection (cycle-by-cycle and latched), over-voltage protection (115% VOUT, two-cycle detection), under-voltage protection (73% VOUT, 16-cycle detection), thermal shutdown (155°C with 30°C hysteresis), and input UVLO (6.3 V rising). All protections are detailed in the "Protections" section and Electrical Characteristics table. The FAN21SV04EMPX also features fault latch behavior with configurable EN-based auto-restart or latched-off modes per Table 1.
FAN21SV04EMPX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- TinyBuck®
- Package/Case:
- 25-WQFN 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):
- 3V
- Voltage - Input (Max):
- 24V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 19.2V
- Current - Output:
- 4A
- Frequency - Switching:
- 200kHz ~ 600kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 25-MLP (6x5)
FAN21SV04EMPX FAQ
1.How can I place an order for FAN21SV04EMPX through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN21SV04EMPX 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 FAN21SV04EMPX reliable?
The price and inventory of FAN21SV04EMPX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN21SV04EMPX is usually 5 days.
3.What payment methods are accepted for FAN21SV04EMPX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN21SV04EMPX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN21SV04EMPX?
FAN21SV04EMPX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN21SV04EMPX 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 FAN21SV04EMPX?
For technical support, including FAN21SV04EMPX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN21SV04EMPX requirements.
6.How does Aetrix verify that FAN21SV04EMPX is sourced from the original manufacturer or authorized distributors?
All FAN21SV04EMPX 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 FAN21SV04EMPX meets industry standards.
7.What is the process for return or replacement of FAN21SV04EMPX?
All FAN21SV04EMPX units undergo pre-shipment inspection (PSI). If there is an issue with FAN21SV04EMPX, 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 FAN21SV04EMPX part is unused and in its original packaging.
Return procedure for FAN21SV04EMPX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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