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Analog Devices Inc./Maxim Integrated MAX42403AFLA+T
- Part No.:
- MAX42403AFLA+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 15-PowerWFQFN
- Datasheet:
-
MAX42403AFLA+T.pdf
- Description:
- IC REG BUCK ADJ 3.5A 15FC2QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,452
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Product details
Overview
MAX42403AFLA+T from Analog Devices is a fully integrated 36V, 3.5A synchronous buck converter in a 3mm × 3mm FC2QFN package, featuring 4.5V–36V input range, adjustable 0.8V–14V output (at 400kHz), 99% dropout duty cycle, and 27μA quiescent current in skip mode - designed for industrial point-of-load power delivery.
For engineers reviewing the MAX42403AFLA+T datasheet, MAX42403AFLA+T pinout, MAX42403AFLA+T application, or MAX42403AFLA+T equivalent, key selection considerations include its 400kHz fixed switching frequency, spread-spectrum EMI reduction, PGOOD monitoring, programmable UVLO via EN threshold, and thermal/overvoltage/short-circuit protection - all within a compact, thermally optimized footprint.
Technical Context
The MAX42403AFLA+T implements average current-mode control with internal slope compensation, enabling stable operation across wide VIN–VOUT ratios and supporting minimum on-time of 37ns for high step-down ratios. Its dual-mode operation - forced PWM (via SYNC high) or automatic skip mode (SYNC low) - balances light-load efficiency and EMI predictability.
It integrates high-side (96mΩ typ) and low-side (46mΩ typ) DMOS FETs, a 1.8V BIAS LDO with 2.2μF decoupling requirement, and a windowed PGOOD comparator with ±2.25% UV/OV thresholds referenced to VOUT. Thermal shutdown activates at 175°C with 15°C hysteresis, and hiccup-mode short-circuit protection cycles with 25ms off-time at 400kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 36V - supports wide industrial DC rails including 12V, 24V, and 36V systems without pre-regulation. |
| Output Current Rating | 3.5A continuous - enables single-chip power for FPGA I/O banks, PLC modules, or sensor signal chains. |
| Switching Frequency | 400kHz fixed - allows use of compact 6.8μH inductors and reduces EMI fundamental while maintaining transient response. |
| Output Voltage Range | 0.8V to 14V (adjustable via resistor divider) - covers core logic (0.8–1.2V), I/O (1.8–3.3V), and analog subsystems (5V, 12V). |
| Quiescent Current | 27μA in skip mode - extends battery life in always-on industrial sensors or remote monitoring nodes. |
| Duty Cycle Max | 99% - sustains regulation down to VIN ≈ VOUT + 0.36V, critical for brownout resilience in 12V-powered field devices. |
| Thermal Shutdown | 175°C with 15°C hysteresis - protects against sustained overload or poor heatsinking in enclosed enclosures. |
| PGOOD Accuracy | ±2.25% windowed threshold (93–105% VOUT) - ensures reliable system-level power sequencing and fault detection. |
Pinout & Package
MAX42403AFLA+T is housed in a 15-pin FC2QFN package (3mm × 3mm, 0.4mm pitch) with exposed thermal pad. The symmetrical SUP/PGND pin layout minimizes loop inductance and improves EMI performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN | Enable input | High-voltage-tolerant (up to 42V), active-high digital control; enables BIAS LDO and converter startup when >0.9V. |
| SUP (Pins 3,7) | High-side supply input | Power source for internal gate drivers; requires local 0.1μF + 2.2μF ceramic bypass per pin for low-impedance switching current return. |
| PGND (Pins 4,6) | Power ground | High-current return path for LX switch node; must be connected directly to thermal pad and share low-inductance plane with SUP capacitors. |
| LX | Switch node | Connection to inductor; carries full AC switching current; requires minimal trace area to reduce radiated EMI and dv/dt noise coupling. |
| BST | Bootstrap capacitor terminal | Drives high-side FET gate; requires 0.1μF ceramic capacitor between BST and LX to sustain gate voltage during 99% duty cycle operation. |
| BIAS | Internal 1.8V LDO output | Powers analog circuitry; requires ≥2.2μF ceramic capacitor to PGND for stability and noise rejection. |
| FB | Feedback input | Resistor-divider input referenced to 0.8V internal reference; sets output voltage with ±1.5% typical accuracy over temperature. |
| PGOOD | Open-drain power-good | Active-high status flag pulled low if VOUT falls below 93% or rises above 105%; requires external 20kΩ pullup to BIAS or system rail. |
| SYNC | Mode control & sync input | Logic-level pin: low = skip mode, high = forced PWM, external clock = synchronization; enables EMI optimization and timing coordination. |
| SPS | Spread-spectrum enable | High = ±6% triangular frequency modulation active; disabled during external sync; reduces peak EMI by spreading energy across bandwidth. |
| GND | Analog ground | Quiet reference for feedback and internal comparators; must be tied to PGND under IC via multiple vias to minimize noise coupling. |
| NC (Pins 2,8) | No connect | Unbonded pins; must remain unconnected and unpopulated on PCB to avoid parasitic coupling or mechanical stress. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated high- and low-side FETs | Reduces BOM count to only inductor, input/output caps, and feedback resistors - enables <10 mm² total solution size. |
| 99% maximum duty cycle | Enables operation in dropout during brownouts (e.g., 12V input dropping to 12.5V while regulating 12V output), critical for factory automation uptime. |
| Programmable EN UVLO threshold | Adjustable startup voltage (2.6–3.15V) via external resistor divider on EN - supports custom power sequencing in multi-rail systems. |
| Internal soft-start | Fixed 2.5ms ramp time at 400kHz - limits inrush current into bulk capacitance and prevents input rail collapse during cold start. |
| Windowed PGOOD with debounce | 180μs rising / 70μs falling debounce at 1.5MHz - eliminates false triggers from transient load steps or line noise while ensuring fast fault reporting. |
| Hiccup-mode short-circuit protection | 25ms off-time at 400kHz - limits average power dissipation during sustained faults, preventing thermal runaway without requiring external current sense. |
Applications
| Industrial PLC I/O Modules | Factory Floor Sensors |
|---|---|
Use Scenario: Powering isolated analog input channels and digital I/O drivers in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Primary 3.3V/5V point-of-load regulator delivering 3.5A peak to ADCs, isolators, and bus transceivers. Use Value: 99% duty cycle maintains regulation during 24V supply dips to 25V; PGOOD enables safe I/O disable before undervoltage lockout. | Use Scenario: Compact, sealed environmental sensors (temperature, vibration, pressure) deployed in harsh manufacturing zones. IC Role / Device Role / Timing Role: Main power stage converting 12V vehicle/bus power to 3.3V for microcontroller and wireless SoC. Use Value: 27μA skip-mode IQ extends battery life in wireless edge nodes; spread-spectrum reduces EMI to meet CISPR 22 Class A emissions limits. |
| Ruggedized HMI Displays | Motor Drive Auxiliary Supplies |
Use Scenario: Power management for 4.3″–7″ touch HMI panels operating in ambient temperatures up to +70°C inside control cabinets. IC Role / Device Role / Timing Role: 12V-to-5V conversion for display backlight drivers and touchscreen controllers. Use Value: -40°C to +125°C junction rating ensures reliability under thermal cycling; FC2QFN package withstands mechanical shock/vibration. | Use Scenario: Isolated auxiliary supply for gate drivers and current sensing in 3-phase servo motor inverters. IC Role / Device Role / Timing Role: 15V-to-12V regulation powering isolated SiC gate driver bias rails. Use Value: High-side FET RDS(on) of 96mΩ minimizes conduction loss at 1.5A; thermal shutdown prevents latch-up during MOSFET short events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM61480RQWR | 4.5V–36V input, 8A rating, 2.1MHz switching, no integrated spread spectrum, higher IQ (40μA) | Targets higher-current motor control or compute loads; lacks PGOOD windowing and hiccup-mode short-circuit behavior | Choose LM61480RQWR only when >3.5A output or faster transient response is required; verify external EMI filtering needed. |
| TPS543320RHLR | 4.5V–20V input, 3A rating, 1.5MHz/2.2MHz selectable, PMBus interface, no dropout mode beyond 90% | Designed for digitally controlled server/telecom supplies; lacks industrial-grade temp range and 36V tolerance | Use TPS543320RHLR where telemetry, margining, or dynamic voltage scaling is essential - not for 24V/36V industrial inputs. |
Compared with LM61480RQWR and TPS543320RHLR, MAX42403AFLA+T uniquely combines 36V tolerance, 99% dropout, integrated spread spectrum, and -40°C to +125°C operation - making it the optimal choice for space-constrained, thermally demanding industrial power nodes where reliability trumps programmability.
Availability
MAX42403AFLA+T is available at Aetrix Electronics and suitable for industrial automation, point-of-load regulation, and distributed DC power systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for MAX42403AFLA+T 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 MAX42402/MAX42403 family was engineered specifically for rugged, space-constrained industrial power conversion - emphasizing wide-input operation, thermal robustness, EMI control, and functional safety features like windowed PGOOD and hiccup-mode protection.
FAQ
What is the maximum output current capability of the MAX42403AFLA+T?
The MAX42403AFLA+T delivers up to 3.5A continuous output current under thermal-limited conditions (TA ≤ +70°C on multilayer board). This rating assumes proper PCB copper area, thermal vias to inner ground planes, and airflow. At elevated ambient temperatures or with reduced copper, derating applies per θJA = 51°C/W (JEDEC board) - e.g., at TA = +85°C, max load drops to ~2.7A.
Does the MAX42403AFLA+T support external synchronization of its switching frequency?
Yes, the MAX42403AFLA+T supports external clock synchronization via the SYNC pin. When driven with a clean square wave in the range of 360–600kHz (for 400kHz internal mode) or 1.215–1.845MHz (for 1.5MHz mode), the device locks to the external clock within two cycles. During absence of the external clock for >2 cycles, it automatically reverts to its internal oscillator.
How does the MAX42403AFLA+T implement overvoltage protection?
The MAX42403AFLA+T uses active overvoltage protection: when VOUT exceeds 105% of nominal in skip mode, the high-side FET turns OFF and low-side FET turns ON until inductor current reaches a fixed negative threshold, rapidly discharging the output. This mechanism responds within microseconds and complements the windowed PGOOD flag for system-level fault handling.
Can the MAX42403AFLA+T operate with an input voltage lower than 4.5V?
No - the absolute minimum specified input voltage for normal operation of the MAX42403AFLA+T is 4.5V. Below this, the internal regulators (BIAS, gate drivers) cannot sustain bias, and the device may fail to start or exhibit erratic behavior. The absolute maximum rating of -0.3V to +42V does not imply functional operation at sub-4.5V levels.
What is the purpose of the SPS pin on the MAX42403AFLA+T?
The SPS (Spread Spectrum) pin enables or disables ±6% triangular frequency modulation of the internal oscillator. When pulled high, it spreads switching energy across a 120kHz band (at 400kHz base) or 180kHz band (at 1.5MHz base), reducing peak radiated EMI by up to 10dB. It is automatically disabled during external clock synchronization to preserve timing integrity.
MAX42403AFLA+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 15-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):
- 36V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 12V
- Current - Output:
- 3.5A
- Frequency - Switching:
- 400kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 15-FC2QFN (3x3)
MAX42403AFLA+T FAQ
1.How can I place an order for MAX42403AFLA+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX42403AFLA+T 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 MAX42403AFLA+T reliable?
The price and inventory of MAX42403AFLA+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX42403AFLA+T is usually 5 days.
3.What payment methods are accepted for MAX42403AFLA+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX42403AFLA+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX42403AFLA+T?
MAX42403AFLA+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX42403AFLA+T 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 MAX42403AFLA+T?
For technical support, including MAX42403AFLA+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX42403AFLA+T requirements.
6.How does Aetrix verify that MAX42403AFLA+T is sourced from the original manufacturer or authorized distributors?
All MAX42403AFLA+T 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 MAX42403AFLA+T meets industry standards.
7.What is the process for return or replacement of MAX42403AFLA+T?
All MAX42403AFLA+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX42403AFLA+T, 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 MAX42403AFLA+T part is unused and in its original packaging.
Return procedure for MAX42403AFLA+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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