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Analog Devices Inc./Maxim Integrated MAX25255AFDB/VY+T
- Part No.:
- MAX25255AFDB/VY+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 23-PowerWFQFN
- Datasheet:
-
MAX25255AFDB/VY+T.pdf
- Description:
- IC REG BUCK 3.3V/5V DL 23FC2QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,944
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Product details
Overview
MAX25255AFDB/VY+T from Analog Devices is a dual-channel, automotive-grade synchronous buck converter IC with integrated 8A-per-channel MOSFETs, ASIL B functional safety certification, and multiphase capability. It operates from 3V to 36V input, delivers up to 8A per channel, achieves 99% duty cycle in dropout, and features 12µA quiescent current in single-channel active mode - enabling robust front-end power for head units and telematics modules.
For engineers reviewing the MAX25255AFDB/VY+T datasheet, MAX25255AFDB/VY+T pinout, MAX25255AFDB/VY+T application, or MAX25255AFDB/VY+T equivalent, key selection considerations include ASIL B diagnostic coverage (redundant reference, die temperature monitor, ±1% OVP/UVP accuracy), dual/quad-phase scalability (up to 32A), and 23-pin FC2QFN thermal performance (θJCb = 4.8°C/W).
Technical Context
The MAX25255AFDB/VY+T implements two independent synchronous buck regulators with MAXQ® power architecture, delivering precision transient response and phase margin control. Each channel supports programmable output (0.8V–14V), 200kHz–2MHz switching frequencies, and 180° out-of-phase operation for reduced input ripple.
It integrates ASIL B–compliant diagnostics including redundant voltage reference, precision overvoltage/undervoltage protection (±1% accuracy), die temperature monitoring via TEMP pin (0.75V at +25°C), and thermal shutdown at +175°C with 15°C hysteresis - all validated per ISO 26262 requirements for automotive safety-critical systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.0V to 36V (42V absolute max); enables direct battery connection in 12V/24V automotive systems without pre-regulation. |
| Output Current per Channel | Up to 8A continuous (at 400kHz); derates to 6A at 2MHz for optimal size-efficiency tradeoff. |
| Quiescent Current | 12µA (typ) with one channel enabled; sustains always-on functionality in low-power telematics and camera modules. |
| Switching Frequency Options | 200kHz / 400kHz / 1MHz / 2MHz; fixed-frequency PWM avoids AM band interference and simplifies EMI filtering. |
| ASIL B Compliance | Fully certified per ISO 26262; includes redundant reference, die temp monitor, ±1% OVP/UVP accuracy, and active timeout (6.0ms typ). |
| Thermal Resistance (θJCb) | 4.8°C/W (4-layer board); enables high-power density layout with minimal heatsinking in compact 4.50mm × 5.75mm FC2QFN package. |
| Minimum On-Time | 24ns (typ); supports high VIN-to-VOUT conversion ratios (e.g., 36V→3.3V) without pulse-skipping instability. |
Pinout & Package
MAX25255AFDB/VY+T is housed in a 23-pin, 4.50mm × 5.75mm FC2QFN package with exposed thermal pad (pin 13 PGND1 and pin 6 PGND2 serve as primary thermal paths). The package supports AEC-Q100 Grade 1 qualification (−40°C to +125°C ambient) and RoHS compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 SYNC | Synchronization input | Configures FPWM (high) or skip mode (low); accepts external clock (380kHz–2.5MHz) for system-wide timing alignment. |
| 2 EN2, 13 EN1 | Channel enable inputs | High-voltage tolerant (≥1.8V logic); allow independent control of each buck stage, including battery-direct always-ON operation. |
| 3 BST2, 12 BST1 | Bootstrap supply terminals | Drive high-side MOSFET gates; require 0.1µF ceramic caps to LX2/LX1 for proper bootstrap charging and gate drive integrity. |
| 4 LX2, 11 LX1 | Switch node connections | Connect to external inductors; high-impedance when respective channel disabled; support 10A RMS continuous current. |
| 6 PGND2, 9 PGND1, 13 PGND1 | Power ground returns | Dedicated low-inductance paths for each buck stage; must be connected to PCB ground plane with multiple vias for thermal and EMI performance. |
| 14 SYNCOUT | 90° out-of-phase clock output | Enables quad-phase operation when connected to SYNC of secondary IC; active only in FPWM mode. |
| 15 PGOOD1, 23 PGOOD2 | Open-drain power-good outputs | Indicate regulation status (UV/OV fault or startup); pulled low during soft-start or violation; require external pull-up to BIAS or rail. |
| 16 OUT1/FB1, 22 OUT2/FB2 | Output sense / feedback inputs | Fixed-output version: connect OUTx to VOUT; adjustable version: use resistor divider to set 0.8V–14V; FB regulated to 0.8V (typ). |
| 17 TEMP | Die temperature monitor | Outputs voltage proportional to junction temp (VTMP = 2.6×TJ + 685 mV); enables real-time thermal management in FPWM mode. |
| 18 VEA | Error amplifier output | Used for current sharing in dual/quad-phase configurations; tie VEA pins together across ICs to balance load between phases. |
| 20 BIAS | Internal 1.8V LDO output | Powers internal gate drivers; bypass with ≥4.7µF ceramic cap to AGND; not intended for external loads. |
| 21 EXTVCC | BIAS LDO switchover input | Reduces internal power dissipation by switching BIAS supply from SUP1 to buck output or external rail; activates at >2.5V. |
Key Features
| Feature | Design Value |
|---|---|
| ASIL B Functional Safety Architecture | Includes redundant voltage reference, die temperature monitor, ±1% OVP/UVP accuracy, and active timeout (6.0ms) - certified per ISO 26262 for automotive safety-critical power rails. |
| Multiphase Scalability | Supports dual-phase (16A) using two channels on one IC, and quad-phase (32A) using two ICs with 90° phase shift via SYNCOUT→SYNC and shared VEA nodes. |
| Ultra-Low Quiescent Current | 12µA (typ) with one channel active and no switching; extends battery life in always-on automotive modules such as ADAS cameras and telematics. |
| MAXQ® Power Architecture | Delivers precision transient response and optimized phase margin, enabling stable regulation under dynamic load steps without external compensation. |
| Dropout Operation | 99% maximum duty cycle allows regulation down to VOUT ≈ VIN − 0.5V (e.g., 3.3V output from 3.6V input), critical for cold-crank automotive scenarios. |
| Spread-Spectrum EMI Reduction | ±6% frequency modulation centered at fSW (4.5kHz triangle wave at 2MHz) lowers peak EMI by >10dB without compromising regulation performance. |
Applications
| Front-End Power Supply for Head Units | ASIL B–Compliant Telematics Module |
|---|---|
|
Use Scenario: Powers infotainment SoC, display interface, and audio subsystems in automotive head units with strict cold-crank (≥3.6V) and load-dump (42V) resilience. IC Role / Device Role / Timing Role: Dual-buck regulator providing isolated 5V/3.3V rails with independent enable control and PGOOD monitoring for system sequencing. Use Value: 99% duty cycle maintains regulation during engine cranking; ASIL B diagnostics ensure fail-safe reporting to vehicle controller during OVP/UVP events. |
Use Scenario: Supplies LTE/V2X modem, GNSS receiver, and MCU in telematics control units requiring continuous connectivity and functional safety. IC Role / Device Role / Timing Role: Primary power source with redundant reference and die temperature sensing, feeding safety-critical communication subsystems. Use Value: ±1% OVP/UVP accuracy and 6ms active timeout meet ASIL B diagnostic coverage targets; 12µA IQ enables 10-year battery backup runtime. |
| Front Camera Power System | Dual-Phase ADAS Domain Controller Rail |
|
Use Scenario: Delivers clean, low-noise 1.8V/3.3V power to high-resolution image sensors and ISP in front-facing ADAS cameras. IC Role / Device Role / Timing Role: Dual-channel buck converter operating in 180° out-of-phase mode to minimize input capacitor RMS current and EMI. Use Value: 24ns minimum on-time supports 12V→1.8V conversion without instability; spread-spectrum mode reduces radiated emissions near sensitive analog video paths. |
Use Scenario: Generates 5V@16A rail for domain controller SoCs using dual-phase configuration across two MAX25255AFDB/VY+T channels. IC Role / Device Role / Timing Role: Phase-balanced dual-buck stage with shared VEA loop and 180° interleaving to halve input ripple and reduce bulk capacitance. Use Value: ±10% current sharing accuracy ensures balanced thermal loading; θJCb = 4.8°C/W enables 16A operation without forced air cooling in sealed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel automotive buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX25254AFDB/VY+T | No ASIL B diagnostics (no redundant reference, no die temp monitor, ±3% OVP/UVP accuracy); identical pinout and electrical specs otherwise. | Suitable for non-safety-critical dual-buck applications (e.g., body electronics, lighting) where ISO 26262 compliance is not required. | Select MAX25254AFDB/VY+T only when ASIL B certification, precise fault detection, or thermal monitoring are unnecessary. |
| TPS65321A-Q1 | Single 3A buck + dual LDO; no multiphase capability; lower current per channel; different pinout and control interface (SPI-configurable). | Targeted at MCU power domains with mixed analog/digital supplies; lacks dual high-current buck scalability and ASIL B hardware diagnostics. | Choose TPS65321A-Q1 for cost-sensitive, lower-current applications needing integrated LDOs but not dual 8A capability or quad-phase expansion. |
Compared with MAX25254AFDB/VY+T and TPS65321A-Q1, the MAX25255AFDB/VY+T uniquely combines ASIL B certification, dual 8A channels, multiphase scalability to 32A, and 23-pin FC2QFN thermal efficiency - making it the only option for safety-critical, high-current automotive power rails requiring field-proven functional safety hardware.
Availability
MAX25255AFDB/VY+T is available at Aetrix Electronics and suitable for automotive head unit power, ASIL B telematics modules, front camera systems, and ADAS domain controllers requiring stable component supply across extended temperature and safety-critical design cycles.
Supply support for MAX25255AFDB/VY+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 power management semiconductors, serving automotive, industrial, and communications markets with ISO 26262–certified solutions.
The MAX25255AFDB/VY+T belongs to Analog Devices' MAX25254/MAX25255 family of automotive-qualified dual buck converters, designed specifically for ASIL B–compliant front-end power in head units, telematics, and ADAS systems demanding high current, low IQ, and functional safety.
FAQ
What is the ASIL B safety coverage implemented in MAX25255AFDB/VY+T?
The MAX25255AFDB/VY+T implements full ASIL B–compliant hardware diagnostics per ISO 26262, including redundant voltage reference, die temperature monitoring via TEMP pin, ±1% overvoltage/undervoltage protection accuracy, and active timeout circuitry (6.0ms typical). These features are validated in the device's safety manual and enable safe state transitions during fault conditions without software intervention - a core requirement for automotive safety-critical power rails.
Can MAX25255AFDB/VY+T operate in dropout mode, and what is the minimum input-to-output voltage difference supported?
Yes, the MAX25255AFDB/VY+T supports dropout operation with up to 99% duty cycle, enabling regulation when input voltage approaches output voltage. For example, it can maintain 3.3V output with input as low as ~3.6V (allowing ~0.3V headroom), which is essential for automotive cold-crank scenarios. This behavior is guaranteed across −40°C to +125°C ambient and does not require external components or configuration changes.
How does the multiphase capability of MAX25255AFDB/VY+T scale beyond dual-channel operation?
The MAX25255AFDB/VY+T supports quad-phase operation by connecting two ICs: one configured as primary (using SYNCOUT) and another as secondary (using SYNC input). The 90° phase shift reduces input ripple and allows up to 32A total output current. Current sharing is enforced via tied VEA pins, and PGOOD signals are cross-connected to report combined status - all without modifying the MAX25255AFDB/VY+T's internal firmware or pin configuration.
What is the role of the EXTVCC pin on MAX25255AFDB/VY+T, and how does it improve efficiency?
The EXTVCC pin on MAX25255AFDB/VY+T enables switchover of the internal 1.8V BIAS LDO supply from SUP1 to an external rail (e.g., buck output or auxiliary supply). When EXTVCC exceeds 2.5V, the LDO input switches automatically, reducing power dissipation in the IC and improving light-load efficiency - especially valuable in always-on automotive modules where 12µA quiescent current must be sustained for years.
Does MAX25255AFDB/VY+T support spread-spectrum modulation, and how does it affect EMI performance?
Yes, MAX25255AFDB/VY+T includes hardware-enabled spread-spectrum modulation with ±6% frequency deviation centered at the selected switching frequency (e.g., 2MHz ±120kHz). This triangular modulation at 4.5kHz lowers peak radiated EMI by >10dB compared to fixed-frequency operation, easing compliance with CISPR 25 Class 5 without adding ferrites or shielding - while maintaining regulation accuracy and transient response.
MAX25255AFDB/VY+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 23-PowerWFQFN
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Fixed
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 3.3V, 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 8A, 8A
- Frequency - Switching:
- 400kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 23-FC2QFN (4.5x5.75)
MAX25255AFDB/VY+T FAQ
1.How can I place an order for MAX25255AFDB/VY+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX25255AFDB/VY+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 MAX25255AFDB/VY+T reliable?
The price and inventory of MAX25255AFDB/VY+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX25255AFDB/VY+T is usually 5 days.
3.What payment methods are accepted for MAX25255AFDB/VY+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX25255AFDB/VY+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX25255AFDB/VY+T?
MAX25255AFDB/VY+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX25255AFDB/VY+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 MAX25255AFDB/VY+T?
For technical support, including MAX25255AFDB/VY+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX25255AFDB/VY+T requirements.
6.How does Aetrix verify that MAX25255AFDB/VY+T is sourced from the original manufacturer or authorized distributors?
All MAX25255AFDB/VY+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 MAX25255AFDB/VY+T meets industry standards.
7.What is the process for return or replacement of MAX25255AFDB/VY+T?
All MAX25255AFDB/VY+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX25255AFDB/VY+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 MAX25255AFDB/VY+T part is unused and in its original packaging.
Return procedure for MAX25255AFDB/VY+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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