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onsemi FAN2356MPX
- Part No.:
- FAN2356MPX
- Manufacturer:
- onsemi
- Package:
- 34-PowerTFQFN
- Datasheet:
-
FAN2356MPX.pdf
- Description:
- IC REG BUCK ADJ 6A 34PQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,814
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Product details
Overview
FAN2356MPX from ON Semiconductor (formerly Fairchild) is a 6 A synchronous buck regulator IC designed for high-efficiency DC-DC conversion in power management subsystems. It operates from 4.5 V to 24 V input, delivers adjustable output from 0.6 V to 5.5 V with ±1% reference accuracy, supports programmable switching frequency (200 kHz–1.5 MHz), and integrates internal boot diode and thermal shutdown - deployed in notebook CPU core supplies and telecom base station POL converters.
For engineers reviewing the FAN2356MPX datasheet, pinout, applications, or equivalent options, key selection considerations include its constant on-time control architecture, PFM/ultrasonic light-load mode, valley-current limiting via ILIM pin, precision FB voltage trip point (596 mV typ), and 34-lead PQFN (5.5 mm × 5.0 mm) thermal performance (θJA = 35°C/W).
Technical Context
The FAN2356MPX employs Fairchild's constant on-time (COT) modulation with VIN feed-forward, enabling fixed-frequency operation in CCM and variable-frequency PFM in DCM - delivering excellent line/load transient response without loop compensation. Its modulator uses an internal 2.3 pF capacitor and frequency-setting resistor (RFREQ) to generate tON, while minimum off-time (tOFF,MIN = 320 ns) ensures stable current sensing and prevents multiple pulsing.
Protection is implemented at silicon level: dual-level over-voltage detection (108–115% and 118–125% of VREF), under-voltage lockout on VCC (4.4 V rising threshold), thermal shutdown at 155°C with 15°C hysteresis, and valley-current limiting calibrated to ±10% accuracy at 7 A. The PGOOD open-drain output asserts low during UV/OV/OT faults.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4.5 V to 24 V - supports wide-input industrial and computing rails including 12 V and 19 V adapter inputs. |
| Output Current | 6 A continuous - sufficient for CPU/GPU core supplies in mainstream notebooks and embedded controllers. |
| FB Reference Voltage | 596 mV (typ), ±1% over temperature - enables precise 0.6–5.5 V output programming with minimal drift. |
| Switching Frequency | 200 kHz to 1.5 MHz, programmable via FREQ pin resistor - allows EMI optimization and inductor size trade-offs. |
| Efficiency Peak | 96% - achieved at mid-load with optimized external components; enabled by synchronous rectification and PFM mode. |
| Thermal Resistance | θJA = 35°C/W on 4-layer PCB (7 cm × 7 cm, 1 oz copper) - supports high-power density layouts without forced airflow. |
| Shutdown Current | 10 µA - enables ultra-low quiescent power in battery-backed or always-on systems. |
Pinout & Package
Package: 34-lead PQFN, 5.5 mm × 5.0 mm, exposed thermal pad (P1 = AGND, P2 = PVIN, P3 = SW). Thermal pad must be soldered to PCB ground plane for optimal θJA performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN (P2, pins 5–11) | Power stage input supply | High-current path for HS/LS MOSFETs; requires low-impedance bulk capacitance near package. |
| SW (P3, pins 2,12–17,22) | Switching node | Junction of HS and LS MOSFETs; critical for layout - minimize loop area to reduce EMI and voltage ringing. |
| BOOT (pin 3) | High-side gate driver supply | Capacitor from BOOT to SW provides charge for HS turn-on; internal diode recharges it from PVCC during freewheeling. |
| ILIM (pin 24) | Valley current limit setpoint | Resistor between ILIM and SW programs current limit threshold with ±10% accuracy at 7 A. |
| FB (pin 27) | Output voltage feedback | Compares VOUT via resistive divider to 596 mV reference; ripple injection may be needed for ceramic-cap stability. |
| PGOOD (pin 30) | Open-drain fault indicator | Pulls low during UV/OV/OT faults; requires external pull-up for system sequencing or monitoring. |
Key Features
| Feature | Design Value |
|---|---|
| Constant on-time control | Eliminates need for external compensation network; maintains stable regulation across wide VIN/VOUT ranges. |
| PFM with ultrasonic clamp | Reduces switching frequency at light load while clamping minimum fSW >18 kHz to avoid audible noise. |
| Programmable soft-start | Internal 10 µA current source charges external CSS; startup time = 0.6 × CSS (e.g., 15 nF → 1 ms). |
| Dual OV protection levels | First level (108–115% VREF) disables both FETs; second level (118–125% VREF) forces LS on until power cycle. |
| Pre-bias startup support | Enables safe start into precharged output without discharging VOUT; LS disabled until first PWM edge. |
Applications
| Server VR12 Core Supply | Notebook CPU Core Regulator |
|---|---|
Use Scenario: Provides tightly regulated 1.0–1.3 V core voltage to multi-core Xeon processors in 1U rack servers with dynamic load steps up to 100 A/µs. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing phase interleaving via external drivers; regulates VDDQ and VDDIO with fast transient response. Use Value: Constant on-time architecture achieves <100 µs recovery from 50% load step; PFM mode reduces idle power by 40% vs. fixed-frequency alternatives. |
Use Scenario: Powers Intel Core i5/i7 CPU cores in 14–15.6" thin-and-light notebooks with 19 V adapter input and thermally constrained chassis. IC Role / Device Role / Timing Role: Single-phase buck regulator with integrated gate drivers; handles burst-mode loads during video encoding or gaming. Use Value: 96% peak efficiency extends battery runtime; 34-lead PQFN package enables compact layout with θJA = 35°C/W on 4-layer board. |
| Telecom Base Station POL | Industrial FPGA I/O Supply |
Use Scenario: Generates 3.3 V or 5 V auxiliary rail for RF transceiver ASICs in LTE macro base stations operating at -40°C to +85°C ambient. IC Role / Device Role / Timing Role: Point-of-load regulator with robust OVP/UVP/OTP protection; interfaces with PMBus-compatible supervisory MCU. Use Value: Dual OV thresholds prevent false trips during RF burst transients; thermal hysteresis (15°C) avoids oscillation near shutdown threshold. |
Use Scenario: Supplies configurable 1.2–2.5 V I/O banks for Xilinx Kintex-7 or Intel Cyclone V FPGAs in factory automation PLCs with 24 V DC input. IC Role / Device Role / Timing Role: High-reliability buck converter with valley-current limiting and pre-bias startup for hot-swap capability. Use Value: ILIM pin allows field-adjustable current limit (±10% accuracy); SS pin enables ratiometric tracking with other rails during power-up. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2359DJ-LF-Z | 4 A max output, 4.5–26 V input, fixed 500 kHz fSW, no PFM mode, smaller 8-pin SOIC package. | Lacks light-load efficiency optimization; suitable only for constant-load applications where size trumps efficiency. | Choose when board space is critical and load remains >1 A continuously; not recommended for battery-powered or burst-mode use. |
| TPS54620RGYT | 6 A, 4.5–17 V input, adaptive on-time control, 200–1600 kHz programmable fSW, integrated MOSFETs, 16-pin QFN. | Higher integration (HS/LS FETs onboard) but lower max VIN; requires different layout due to integrated power stages. | Prefer when simplifying BOM and reducing external component count is prioritized over max input voltage range. |
Compared with MP2359DJ-LF-Z and TPS54620RGYT, the FAN2356MPX uniquely balances 24 V max input, 6 A capability, PFM-enabled light-load efficiency, and discrete MOSFET flexibility - making it optimal for high-VIN, thermally constrained, and dynamically loaded systems where external FET selection is required.
Availability
FAN2356MPX is available at Aetrix Electronics and suitable for server VR12 core supplies, notebook CPU regulators, and telecom base station POL applications requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for FAN2356MPX 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 (formerly Fairchild Semiconductor) is a global semiconductor supplier specializing in power management, analog, and sensor solutions for automotive, industrial, and computing markets.
The FAN2356MPX belongs to Fairchild's high-current synchronous buck regulator product line, engineered for high-efficiency, high-density DC-DC conversion in computing and communications infrastructure where thermal performance and transient response are critical.
FAQ
What is the maximum input voltage rating for the FAN2356MPX?
The FAN2356MPX has an absolute maximum PVIN rating of 30 V, but its recommended operating input voltage range is 4.5 V to 24 V. Operation above 24 V risks exceeding design margins for internal gate drivers and thermal limits - sustained use beyond 24 V is not supported per datasheet specifications. The FAN2356MPX must be used within this validated range to ensure reliability and warranty coverage.
Does the FAN2356MPX support pre-bias startup, and how is it implemented?
Yes, the FAN2356MPX supports safe pre-bias startup. During initial enable, the low-side MOSFET is held off until the first positive PWM edge, preventing reverse current flow that could discharge the precharged output. The device also enters forced PFM mode during soft-start to maintain positive inductor current. This behavior is inherent to the FAN2356MPX control architecture and requires no external configuration.
How is the switching frequency programmed on the FAN2356MPX?
The FAN2356MPX switching frequency is programmed using an external resistor (RFREQ) connected between the FREQ pin (pin 32) and AGND. Frequency scales inversely with RFREQ value: 56.2 kΩ yields ~500 kHz, while 10 kΩ sets ~1.5 MHz. The relationship is defined by tON = (RFREQ × 2.3 pF × VIN) / VOUT; full details are in the "Setting Switching Frequency" section of the FAN2356MPX datasheet.
What protection features are integrated into the FAN2356MPX?
The FAN2356MPX integrates five hardware-based protections: (1) dual-level over-voltage (108–115% and 118–125% of VREF), (2) under-voltage (86–92% of VREF), (3) valley-current limiting via ILIM pin, (4) thermal shutdown at 155°C with 15°C hysteresis, and (5) VCC UVLO at 4.4 V. All trigger PGOOD assertion and are active during normal operation - no firmware or external circuitry required for basic fault handling.
Can the FAN2356MPX operate with only ceramic output capacitors?
The FAN2356MPX can operate with all-ceramic output capacitors, but stability requires ≥12 mV of ripple on the FB pin. Ceramic-only designs often lack sufficient ESR-induced ripple, so a small RC network (e.g., 10 Ω + 10 nF) must be added between FB and AGND to inject synthetic ripple. This is a documented requirement in the FAN2356MPX datasheet's "Stability" section and applies specifically to the FAN2356MPX control loop design.
FAN2356MPX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- TinyBuck®
- Package/Case:
- 34-PowerTFQFN
- 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):
- 4.5V
- Voltage - Input (Max):
- 24V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 6A
- Frequency - Switching:
- 200kHz ~ 1.5MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 34-PQFN (5.5x5)
FAN2356MPX FAQ
1.How can I place an order for FAN2356MPX through Aetrix?
Please submit a Request for Quotation (RFQ) for FAN2356MPX 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 FAN2356MPX reliable?
The price and inventory of FAN2356MPX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for FAN2356MPX is usually 5 days.
3.What payment methods are accepted for FAN2356MPX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for FAN2356MPX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for FAN2356MPX?
FAN2356MPX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your FAN2356MPX 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 FAN2356MPX?
For technical support, including FAN2356MPX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your FAN2356MPX requirements.
6.How does Aetrix verify that FAN2356MPX is sourced from the original manufacturer or authorized distributors?
All FAN2356MPX 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 FAN2356MPX meets industry standards.
7.What is the process for return or replacement of FAN2356MPX?
All FAN2356MPX units undergo pre-shipment inspection (PSI). If there is an issue with FAN2356MPX, 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 FAN2356MPX part is unused and in its original packaging.
Return procedure for FAN2356MPX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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