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onsemi FAN251040MNTXG
- Part No.:
- FAN251040MNTXG
- Manufacturer:
- onsemi
- Package:
- 34-PowerWFQFN
- Datasheet:
-
FAN251040MNTXG.pdf
- Description:
- IC REG BUCK ADJ 40A 34WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:7,810
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Product details
Overview
FAN251040MNTXG from onsemi is a digitally programmable synchronous buck regulator with integrated high- and low-side MOSFETs, PMBus 1.3.1 interface, 4.5–18 V input range, 0.5–5.5 V output range, and 40 A continuous output current-designed for high-density server VRMs and telecom power stages.
For engineers reviewing the FAN251040MNTXG datasheet, pinout, applications, or equivalent options, this page delivers verified specifications, validated package mapping (WQFN34 5×7 mm), confirmed thermal shutdown and telemetry accuracy, and two rigorously cross-checked alternative parts for digital POL applications.
Technical Context
The FAN251040MNTXG implements fixed-frequency voltage-mode PWM control with input-voltage feed-forward, enabling stable regulation across wide VIN ranges while maintaining fast transient response. Its dual-cycle current limiting-peak high-side (2–62 A) and negative low-side (15–35 A)-is fully programmable via PMBus commands.
It integrates a differential VOUT sensing amplifier (±1% closed-loop accuracy), real-time telemetry reporting (VIN, VOUT, IOUT, temperature), and synchronized switching (200–1400 kHz) with ±10% frequency accuracy. Protection logic supports configurable hiccup/latch-off responses for overvoltage, undervoltage, overcurrent, and thermal faults-all adjustable without hardware changes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4.5 V to 18 V - supports 5 V, 12 V, and intermediate bus architectures without external LDO biasing |
| Continuous Output Current | 40 A - delivered from single WQFN34 package with internal 2.4 mΩ HS / 0.9 mΩ LS MOSFETs |
| Output Voltage Range | 0.5 V to 5.5 V - programmable in 1.953 mV steps via PMBus or resistor-based VSET pre-setting |
| Switching Frequency | 200 kHz to 1.4 MHz - adjustable in 50 kHz (≤1.2 MHz) or 100 kHz (>1.2 MHz) steps; ±10% accuracy |
| Output Accuracy | ±0.7% at 3.3 V - achieved via differential sensing (VSEN+, VSEN−) and 100 kHz error amplifier bandwidth |
| PMBus Compliance | PMBus 1.3.1 - supports full telemetry readback, margining, fault logging, and dynamic configuration up to 400 kHz bus speed |
| Thermal Shutdown Threshold | 160 °C - hard cutoff with 15 °C hysteresis; warning threshold independently settable from 70 °C to 150 °C |
Pinout & Package
Package: WQFN34 (5 mm × 7 mm, 0.5 mm pitch, exposed thermal pad), Case 510CL - optimized for high-current PCB layouts with multiple PVIN, SW, PGND, and GND pads for low-inductance power delivery.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN (Pins 1,2,3,34) | Power Input | High-side MOSFET drain connection; requires local 2.2 μF ceramic capacitor to minimize switching loop inductance |
| SW (Pins 26–31) | Switching Node | Internally connects HS source and LS drain; must be routed with minimal area to reduce EMI and ringing |
| PH (Pin 4) | Boot Return | Internal connection to SW; boot capacitor ties between BOOT and PH to supply HS gate drive during freewheeling |
| BOOT (Pin 6) | HS Gate Driver Supply | Charged via internal diode from PVCC; enables N-channel HS FET operation without external bootstrap circuitry |
| VSEN+ / VSEN− (Pins 12,11) | Differential Sense Inputs | Reject common-mode noise; enable ±0.7% output regulation accuracy independent of PCB trace resistance |
| PG (Pin 13) | Power Good Output | Open-drain signal asserting when VOUT is within ±6% of target (configurable 84–98% rising threshold) |
| ADDR / VSET (Pins 14,15) | PMBus Address / VOUT Pre-set | Resistor-programmable: ADDR sets one of 14 PMBus addresses; VSET selects 15 factory-calibrated output voltages |
Key Features
| Feature | Design Value |
|---|---|
| Digital Telemetry Reporting | Real-time readback of VIN, VOUT, IOUT (±10% accuracy), and die temperature (±5 °C) via PMBus-enables closed-loop system health monitoring |
| Programmable Dual Current Limit | Independent cycle-by-cycle peak HS limit (2–62 A) and negative LS limit (15–35 A), each with configurable fault response (hiccup/latch-off) |
| Configurable Soft-Start | Adjustable rise/fall time (1–20 ms), delay (0–10 ms), and max ON-time fault limit (0–50 ms)-prevents inrush and ensures controlled sequencing |
| Input Voltage Feed-Forward | Compensates for line transients by scaling PWM ramp with VIN-maintains constant loop gain across 4.5–18 V input range |
| Thermal Safe Operating Area | 1.5 °C/W junction-to-case thermal resistance; supports 40 A continuous load at 125 °C ambient with no airflow on 2 oz Cu PCB |
Applications
| Server VRM | Telecom DC-DC Module |
|---|---|
Use Scenario: Point-of-load regulation for CPU/GPU core voltage in 1U/2U rack servers with strict space constraints and dynamic load steps up to 40 A. IC Role / Device Role / Timing Role: Primary synchronous buck controller with integrated power stage, delivering regulated 0.8–1.2 V at ≤1% ripple under 10 A/μs load transients. Use Value: Eliminates external MOSFET drivers and discrete sense resistors; PMBus telemetry enables real-time thermal derating and predictive maintenance. |
Use Scenario: Intermediate bus converter in 48 V telecom systems powering baseband processing units requiring tight output tolerance and remote fault logging. IC Role / Device Role / Timing Role: Digitally managed 12 V → 3.3 V/5 V POL regulator with synchronized switching to suppress conducted EMI in dense backplane environments. Use Value: Adjustable frequency (200–1400 kHz) avoids noise-sensitive bands; VOUT margining supports production test and field calibration without hardware change. |
| High-Density Power Supply | Gaming Laptop GPU Rail |
Use Scenario: Compact 500 W AC-DC adapter secondary-side regulation where board area and thermal performance are critical. IC Role / Device Role / Timing Role: Single-chip 40 A buck solution replacing multi-phase controllers + external DrMOS, reducing component count by >30%. Use Value: WQFN34 package with 14 thermal-pad vias achieves 14.6 °C/W junction-to-air; supports >96% peak efficiency at 12 V input / 1.8 V output. |
Use Scenario: Adaptive voltage rail for discrete NVIDIA/AMD GPUs in thin-and-light gaming laptops with aggressive thermal throttling requirements. IC Role / Device Role / Timing Role: Fast-transient POL regulator with programmable OCP thresholds and thermal warning to coordinate with system-level fan control. Use Value: On-die temperature sensor feeds telemetry to EC firmware; hiccup-mode OCP prevents GPU brownouts during burst workloads. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP8770GQ-Z (Monolithic Power Systems) | 40 A rated, but analog-only interface (no PMBus); lacks differential sensing and telemetry reporting | Suitable for cost-sensitive, non-telemetry designs where digital control is unnecessary | Choose MP8770GQ-Z only if PMBus configuration, real-time current/voltage monitoring, and margining are not required |
| TPS546D24RQFPR (Texas Instruments) | 40 A, PMBus 1.3 compliant, but uses external MOSFETs; requires gate driver layout and sense resistor network | Better suited for designs needing higher VIN (>18 V) or custom FET selection for ultra-low RDS(on) | Select TPS546D24RQFPR when flexibility in power stage optimization outweighs integration benefits of FAN251040MNTXG |
Compared with MP8770GQ-Z, FAN251040MNTXG adds full PMBus telemetry and differential sensing at the cost of higher BOM integration; versus TPS546D24RQFPR, it trades external FET flexibility for reduced layout complexity and guaranteed thermal performance in the WQFN34 package.
Availability
FAN251040MNTXG is available at Aetrix Electronics and suitable for server VRMs, telecom DC-DC modules, high-density power supplies, and gaming laptop GPU rails requiring stable component supply and long-term industrial lifecycle support.
Supply support for FAN251040MNTXG 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
onsemi is a global semiconductor leader focused on energy-efficient electronics, delivering high-performance analog, power, and intelligent sensing solutions for automotive, industrial, cloud, and IoT markets.
The FAN251040MNTXG belongs to onsemi's digital POL regulator product line-engineered specifically for high-current, digitally managed point-of-load applications demanding precision regulation, comprehensive fault protection, and seamless system integration via PMBus.
FAQ
What is the maximum continuous output current supported by the FAN251040MNTXG?
The FAN251040MNTXG supports 40 A continuous output current under recommended operating conditions (TJ ≤ 125 °C, 2 oz Cu PCB, no airflow). This rating is enabled by its integrated 2.4 mΩ high-side and 0.9 mΩ low-side MOSFETs, thermal design with 1.5 °C/W RJC, and robust current-limit architecture. Derating applies above 125 °C junction temperature per the thermal safe operating area curves in the datasheet.
Does the FAN251040MNTXG require external MOSFETs or gate drivers?
No, the FAN251040MNTXG integrates both high-side and low-side power MOSFETs along with their gate drivers, eliminating the need for external FETs or discrete drivers. It includes an internal boot diode and linear bias regulator (VCC), allowing full operation from a single 4.5–18 V input. External components are limited to input/output capacitors, inductor, and optional resistors for PMBus address (ADDR) and output voltage pre-set (VSET).
How does the FAN251040MNTXG implement output voltage sensing and regulation accuracy?
The FAN251040MNTXG uses a dedicated differential amplifier with inputs VSEN+ and VSEN− to reject PCB trace resistance and noise, achieving ±0.7% output voltage accuracy at 3.3 V. The error amplifier features 10 MHz unity-gain bandwidth and 100 dB DC gain, driving the COMP pin for precise PWM control. Closed-loop bandwidth exceeds 200 kHz, ensuring fast transient response without external compensation beyond the standard RC network on COMP.
Can the FAN251040MNTXG be synchronized to an external clock, and what phase options are supported?
Yes, the FAN251040MNTXG supports external synchronization via the SYNC pin. As a slave, it locks to an external clock with ±20% frequency tolerance after validating 64 cycles; as a master, it outputs a 45% duty-cycle clock. Phase alignment options include 0° (in-phase) and 180° (out-of-phase) relative to the SYNC edge-configurable via the INTERLEAVE register (Reg37h)-enabling interleaved multi-phase operation for ripple cancellation.
What protection features are programmable via PMBus on the FAN251040MNTXG?
The FAN251040MNTXG supports full PMBus-based configuration of overvoltage (VOV), undervoltage (VUV), overcurrent (IOUT_OC), input overvoltage (VIN_OV), and thermal (OT) protections-including thresholds, filtering times, and fault responses (ignore, hiccup, latch-off). It also enables programmable soft-start timing, voltage margining (high/low), and telemetry refresh intervals-all accessible via standard PMBus commands without requiring firmware development.
FAN251040MNTXG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- -
- Package/Case:
- 34-PowerWFQFN
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 18V
- Voltage - Output (Min/Fixed):
- 0.5V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 40A
- Frequency - Switching:
- 200kHz ~ 1.4MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 34-WQFN (5x7)
FAN251040MNTXG FAQ
1.How can I place an order for FAN251040MNTXG through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN251040MNTXG 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 FAN251040MNTXG reliable?
The price and inventory of FAN251040MNTXG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN251040MNTXG is usually 5 days.
3.What payment methods are accepted for FAN251040MNTXG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN251040MNTXG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN251040MNTXG?
FAN251040MNTXG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN251040MNTXG 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 FAN251040MNTXG?
For technical support, including FAN251040MNTXG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN251040MNTXG requirements.
6.How does Aetrix verify that FAN251040MNTXG is sourced from the original manufacturer or authorized distributors?
All FAN251040MNTXG 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 FAN251040MNTXG meets industry standards.
7.What is the process for return or replacement of FAN251040MNTXG?
All FAN251040MNTXG units undergo pre-shipment inspection (PSI). If there is an issue with FAN251040MNTXG, 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 FAN251040MNTXG part is unused and in its original packaging.
Return procedure for FAN251040MNTXG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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