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Analog Devices Inc./Maxim Integrated MAX42408AFOB+
- Part No.:
- MAX42408AFOB+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 17-PowerWFQFN
- Datasheet:
-
MAX42408AFOB+.pdf
- Description:
- IC REG BUCK ADJ 8A 17FC2QFN
- Quantity:
- Payment:
- Shipping:
Inventory:704
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Product details
Overview
MAX42408AFOB+ from Analog Devices is a fully integrated 36V, 8A synchronous buck converter with internal high-side and low-side MOSFETs, 1.5MHz fixed switching frequency, 0.8V–6V programmable output voltage, and dual-phase capability for up to 16A in single-IC configuration-designed for industrial point-of-load regulation where compact size and ultra-low light-load efficiency are critical.
For engineers reviewing the MAX42408AFOB+ datasheet, MAX42408AFOB+ pinout, MAX42408AFOB+ application, or MAX42408AFOB+ equivalent, key selection criteria include its 10μA quiescent current in skip mode, 36ns minimum on-time for high step-down ratios, symmetric SUP/PGND pinout for EMI control, and FC2QFN-17 (3.5mm × 3.75mm) thermal performance validated at θJA = 27°C/W on 4-layer evaluation board.
Technical Context
The MAX42408AFOB+ implements average current-mode control with internal 0.8V reference and 36ns minimum on-time, enabling stable operation across wide VIN/VOUT ratios (e.g., 24V→3.3V) without pulse-skipping instability. Its dual-phase architecture supports dynamic current sharing and 180° out-of-phase operation when paired with a second MAX42408AFOB+ or MAX42410 variant.
It integrates a 1.8V BIAS linear regulator with 2.2μF output capacitor requirement, uses external resistor-divider feedback (FB), and features SYNC-controlled mode selection: forced PWM (SYNC high), skip mode (SYNC low), or external clock synchronization (valid AC signal on SYNC). PGOOD provides open-drain output with 92–96% rising/falling thresholds and 70μs debounce at 1.5MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 36V - supports wide industrial input rails including 12V, 24V, and 36V systems without pre-regulation. |
| Output Current | 8A continuous - delivers full rated load at TJ ≤ +125°C with proper PCB copper and thermal vias per FC2QFN layout guidelines. |
| Switching Frequency | 1.5MHz fixed - enables use of sub-1μH inductors (e.g., 0.68μH) and reduces output ripple while maintaining >93% peak efficiency at 12VIN/3.3VOUT. |
| Quiescent Current | 10μA in skip mode - extends battery life in always-on industrial sensors and IoT edge nodes during standby. |
| Output Voltage Range | 0.8V to 6V - programmable via external resistor divider; limited to 6V at 1.5MHz to ensure stability and transient response. |
| Minimum On-Time | 36ns - allows high step-down conversion (e.g., 24V→1.2V at 1.5MHz) without cycle skipping or regulation loss. |
| Thermal Shutdown | 175°C with 20°C hysteresis - protects against sustained overload or poor heatsinking; resumes operation only after junction cools to 155°C. |
Pinout & Package
Package: 3.5mm × 3.75mm, 17-pin FC2QFN (F173A3F+1F) with exposed thermal pad; thermally enhanced for θJC = 8.5°C/W on 4-layer eval board.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 EN | Enable input | High-voltage compatible (up to 42V); drives IC into <4μA shutdown when pulled low. |
| 2 BST | Bootstrap supply | Connects 0.1μF ceramic cap to LX; supplies gate drive for internal high-side FET. |
| 3, 9 SUP | Power input & high-side switch supply | Dual pins internally connected; bypass each with 0.1μF + 4.7μF ceramics to PGND for low-noise operation. |
| 4, 5, 7, 8 PGND | Power ground | Four dedicated low-impedance paths for high-current return; must be tied together and connected to thermal pad. |
| 6, 13 LX | Switch node | Connects to buck inductor; high-impedance when disabled; requires short, wide trace to minimize EMI. |
| 10 GND | Analog ground | Separate from PGND; connect to PGND at single star point to avoid noise coupling into FB/VEA. |
| 11 BIAS | 1.8V linear regulator output | Powers internal circuitry; requires ≥2.2μF ceramic cap to GND; switches source from SUP to VOUT post-startup. |
| 12 FB | Feedback input | Senses output via resistor divider; 0.788–0.812V accuracy ensures ±1.5% output regulation over temp and line. |
| 14 VEA | Error amplifier output | Used only in dual-phase: connects controller and target VEA pins for shared voltage loop and balanced current sharing. |
| 15 PGOOD | Open-drain power good | Asserts low during soft-start or if VOUT drops below 93% of setpoint; requires external pull-up to BIAS or ≤5.5V rail. |
| 16 SYNC | Mode control & sync input | Low = skip mode; high = forced PWM; AC signal = external sync; determines controller/target role in dual-phase. |
| 17 SYNCOUT | 180° out-of-phase clock output | Active only when SYNC = high (FPWM); used to drive SYNC of target IC in dual-phase configuration. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-phase scalability | Two MAX42408AFOB+ ICs deliver up to 16A with dynamic current sharing, 180° phase shift, and shared VEA loop-no external controller required. |
| Ultra-low IQ skip mode | 10μA quiescent current at no load enables >1-year battery life in always-on industrial monitoring devices with intermittent wake cycles. |
| EMI-optimized pinout | Symmetric SUP/PGND placement creates opposing current loops that cancel magnetic fields, reducing radiated emissions without added filtering. |
| Dropout operation | 96% max duty cycle allows regulation down to VOUT ≈ 0.96 × VIN - supports 24V→23V bias rails in legacy industrial backplanes. |
| Robust protection suite | Includes cycle-by-cycle current limit, hiccup-mode short-circuit protection, thermal shutdown (175°C), and PGOOD fault signaling. |
Applications
| Industrial PLC I/O Module Power | Factory Automation Sensor Hub |
|---|---|
|
Use Scenario: Powers isolated analog input/output channels in modular PLC bases requiring clean, stable 3.3V or 5V rails from 24V DC bus. IC Role / Device Role / Timing Role: Primary point-of-load regulator delivering 8A peak to multiple isolated DC-DCs and ADC/DAC peripherals. Use Value: 1.5MHz switching minimizes inductor size and footprint; 36ns min-on-time ensures regulation stability during 24V→5V conversion under fast load transients. |
Use Scenario: Supplies power to multi-sensor fusion nodes (temperature, vibration, current) in predictive maintenance gateways operating on 12–36V field wiring. IC Role / Device Role / Timing Role: Main system regulator with programmable 0.8–6V output, supporting diverse sensor interface voltages (1.8V, 3.3V, 5V) via single design. Use Value: 10μA skip-mode IQ extends operational uptime between battery charges; dual-phase option scales to 16A for future high-density sensor expansion. |
| Ruggedized Edge Compute Node | Distributed DC Power Architecture |
|
Use Scenario: Provides 3.3V/5V power to ARM-based edge controllers in harsh environments (−40°C to +125°C ambient). IC Role / Device Role / Timing Role: High-reliability buck converter with thermal shutdown and -40°C to +125°C guaranteed operation. Use Value: FC2QFN package with exposed thermal pad achieves θJA = 27°C/W on 4-layer board, enabling convection-cooled operation without heatsinks. |
Use Scenario: Serves as scalable building block in distributed power systems where multiple 8A rails feed separate subsystems (e.g., comms, actuation, sensing). IC Role / Device Role / Timing Role: Interleaved dual-phase regulator using two MAX42408AFOB+ ICs to reduce input/output ripple and improve transient response. Use Value: 180° phase shift cuts input RMS current by ~30% vs. single-phase, lowering input capacitor stress and EMI filter requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-efficiency, high-current buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX42410AFOB+T | 10A rated output current; higher ILIM threshold (11.9–16A vs. 10–12A); identical 1.5MHz/0.8–6V spec and pinout. | Preferred for designs requiring >8A margin or higher overload tolerance; same PCB layout and BOM except current-sense calibration. | Select MAX42410AFOB+T when peak load exceeds 8A or long-term reliability under sustained 9–10A is required. |
| LM61480RQR | Texas Instruments 10A buck; 4.5–36V input; 1.5MHz; but 15μA IQ (vs. 10μA), no dual-phase VEA sharing, and different pinout (20-pin WQFN). | Lacks native dual-phase current sharing; requires external controller or complex sequencing for interleaving; higher EMI due to asymmetric PGND layout. | Choose LM61480RQR only if TI ecosystem alignment or specific feature compatibility (e.g., PMBus) outweighs MAX42408AFOB+'s lower IQ and integrated dual-phase capability. |
Compared with MAX42410AFOB+T, the MAX42408AFOB+ offers tighter current-limit tolerance and lower cost for 8A-constrained designs; versus LM61480RQR, it delivers superior light-load efficiency, simpler dual-phase implementation, and better EMI performance through symmetrical FC2QFN layout-without requiring layout redesign.
Availability
MAX42408AFOB+ is available at Aetrix Electronics and suitable for industrial automation, distributed DC power systems, and ruggedized edge compute nodes requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for MAX42408AFOB+ 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
Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.
The MAX42408/MAX42410 product line delivers highly integrated, thermally optimized buck converters for space-constrained industrial point-of-load applications demanding ultra-low IQ, wide input range, and seamless scalability to 20A via dual-phase operation.
FAQ
What is the maximum output voltage supported by the MAX42408AFOB+?
The MAX42408AFOB+ supports an adjustable output voltage range of 0.8V to 6V when configured for 1.5MHz operation. This limit is specified in the datasheet's Electrical Characteristics table and is enforced by internal compensation constraints at high frequency. Attempting to set above 6V at 1.5MHz may result in instability or failure to regulate. For 0.8V–10V operation, the MAX42408AFOA+T (400kHz version) must be used instead.
Can the MAX42408AFOB+ operate in dropout mode, and what is the minimum controllable duty cycle?
Yes, the MAX42408AFOB+ supports dropout operation with up to 96% maximum duty cycle, enabling regulation when VOUT approaches VIN (e.g., 24V→23V). This is achieved through optimized gate drive and low RDS(on) FETs (26mΩ HS / 13mΩ LS). The 36ns minimum on-time ensures stable PWM control even at extreme step-down ratios, preventing pulse skipping and maintaining regulation integrity during deep dropout conditions.
How does dual-phase operation work with two MAX42408AFOB+ ICs, and what connections are required?
In dual-phase mode, one MAX42408AFOB+ acts as controller (SYNC = high) and outputs 180° out-of-phase clock on SYNCOUT; the other acts as target (SYNCOUT tied to BIAS, SYNC connected to controller's SYNCOUT). VEA pins are joined to share the voltage error amplifier, while FB pins use separate resistor dividers. This configuration enables dynamic current sharing and cuts input/output ripple by interleaving, with no external controller needed-fully implemented within the MAX42408AFOB+'s integrated logic.
What is the purpose of the BIAS pin, and how should it be decoupled?
BIAS is the 1.8V output of an internal linear regulator that powers core analog circuitry (reference, error amp, comparators). It must be decoupled with ≥2.2μF ceramic capacitance directly to GND, placed adjacent to the pin. During startup, BIAS draws from SUP; once VOUT exceeds 2.5V, it seamlessly switches to VOUT as source. Incorrect or undersized BIAS capacitance causes reference instability, leading to output voltage drift or PGOOD false trips.
Does the MAX42408AFOB+ support external frequency synchronization, and what are the valid input ranges?
Yes, the MAX42408AFOB+ accepts external clock signals on the SYNC pin for synchronization. When configured for 1.5MHz operation, valid SYNC frequencies range from 1.215MHz to 1.845MHz; for 400kHz operation, the range is 360kHz to 600kHz. The SYNC input has TTL-compatible thresholds (VIH = 1.4V, VIL = 0.4V) and draws only 1μA, enabling direct connection to FPGA clocks or other low-power timing sources without level-shifting.
MAX42408AFOB+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 17-PowerWFQFN
- Packaging:
- Tray
- 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):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 6V
- Current - Output:
- 8A
- Frequency - Switching:
- 1.5MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 17-FC2QFN (3.5x3.75)
MAX42408AFOB+ FAQ
1.How can I place an order for MAX42408AFOB+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX42408AFOB+ 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 MAX42408AFOB+ reliable?
The price and inventory of MAX42408AFOB+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX42408AFOB+ is usually 5 days.
3.What payment methods are accepted for MAX42408AFOB+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX42408AFOB+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX42408AFOB+?
MAX42408AFOB+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX42408AFOB+ 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 MAX42408AFOB+?
For technical support, including MAX42408AFOB+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX42408AFOB+ requirements.
6.How does Aetrix verify that MAX42408AFOB+ is sourced from the original manufacturer or authorized distributors?
All MAX42408AFOB+ 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 MAX42408AFOB+ meets industry standards.
7.What is the process for return or replacement of MAX42408AFOB+?
All MAX42408AFOB+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX42408AFOB+, 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 MAX42408AFOB+ part is unused and in its original packaging.
Return procedure for MAX42408AFOB+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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