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Analog Devices Inc./Maxim Integrated MAX17681ATB+
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- Part No.:
- MAX17681ATB+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
MAX17681ATB+.pdf
- Description:
- IC REG BUCK ADJ 10TDFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,225
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Product details
Overview
The MAX17681ATB+ from Maxim Integrated is a high-voltage, primary-side regulated iso-buck DC-DC controller IC delivering up to 5W isolated output power with peak efficiency >90%, 4.5V–42V input range, and integrated 0.55Ω high-side pMOS / 0.2Ω low-side nMOS switches. It enables optocoupler-free isolated power in industrial fieldbus interfaces and PLC I/O modules.
For engineers reviewing the MAX17681ATB+ datasheet, MAX17681ATB+ pinout, MAX17681ATB+ application, or MAX17681ATB+ equivalent, this page delivers verified technical context, real-world design meaning for each specification, validated pin functions, confirmed alternative parts with documented functional differences, and precise thermal and protection behavior under short-circuit and overtemperature conditions.
Technical Context
The MAX17681ATB+ implements peak-current-mode control with internal slope compensation and cycle-by-cycle current limiting (1.65A typical peak, 1.25A sink). Its primary-side feedback architecture eliminates optocouplers by regulating VPRI, which is scaled via transformer turns ratio to generate isolated secondary outputs.
Unlike the base MAX17681, the MAX17681ATB+ variant adds robust secondary-side overcurrent protection via detection of 16 consecutive negative current limit events, active primary capacitor discharge during hiccup timeout, and coordinated soft-start of both primary and secondary outputs upon recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 42V - supports wide industrial supply rails including 24V nominal and 36V transients without external pre-regulation. |
| Max Output Power | 5W - sufficient for isolated bias supplies in fieldbus nodes, PLC analog I/O, and medical sensor front-ends. |
| Peak Efficiency | >90% - achieved via synchronous operation and low RDS(on) MOSFETs (0.55Ω HS / 0.2Ω LS), reducing thermal load on compact PCBs. |
| Switching Frequency | 186kHz–213kHz - fixed-frequency operation enables predictable EMI filtering and transformer sizing with minimal core loss. |
| Feedback Accuracy | ±1.7% - ensures tight regulation of primary output voltage (VPRI), directly impacting isolation accuracy of secondary rails. |
| Thermal Shutdown | 165°C with 10°C hysteresis - protects against sustained overload or poor heatsinking in sealed industrial enclosures. |
| Shutdown Current | 0.9μA typical - enables ultra-low-power disable states in battery-backed or energy-harvested systems. |
Pinout & Package
Package: 10-pin TDFN (3mm × 2mm), exposed pad (EP) connected to GND for thermal enhancement. RoHS-compliant, JEDEC-standard land pattern (90-0082).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 PGND | Power Ground | High-current return path for LX switching node; must be connected externally to power ground plane and tied to GND at VCC bypass cap. |
| 2 VIN | Input Supply | 4.5V–42V main input; requires X7R ceramic bypass capacitor to PGND for stable high-frequency operation. |
| 3 EN/UVLO | Enable / Input UVLO Input | Active-high logic input; threshold programmable via resistor divider to set turn-on voltage (e.g., 17V–32V); pulls device into 0.9μA shutdown when low. |
| 4 VCC | LDO Output | 5V ±0.35V internal LDO powering internal circuitry and low-side gate driver; requires ≥1μF ceramic bypass to GND. |
| 5 FB | Primary Output Feedback | Monitors VPRI via resistor divider; regulates primary output to 0.9V reference (±1.7%); triggers RESET when VPRI drops below 92.5% of target. |
| 6 SS | Soft-Start Control | 5μA current source charges external capacitor; sets monotonic VPRI ramp time to limit inrush current during startup. |
| 7 COMP | Loop Compensation | Transconductance amplifier output (590μS typ); connects to RC network for stability tuning of peak-current-mode control loop. |
| 8 RESET | Open-Drain Power-Good | Asserts low if VPRI falls below 92.5% or thermal shutdown occurs; releases high-impedance 1024 cycles after VPRI exceeds 95.5%. |
| 9 GND | Signal Ground | Reference for FB, SS, COMP, RESET; must be connected to PGND at VCC bypass capacitor location to minimize noise coupling. |
| 10 LX | Switching Node | Connects to primary winding of transformer; high-impedance in shutdown; carries bidirectional current (peak ±1.6A RMS). |
Key Features
| Feature | Design Value |
|---|---|
| No optocoupler required | Primary-side regulation eliminates optocoupler, reducing BOM cost, board area, and long-term reliability risk in isolation barrier. |
| Synchronous iso-buck topology | Integrated high-side pMOS and low-side nMOS enable efficient energy transfer without external diode losses on primary side. |
| Robust secondary OCP (MAX17681A only) | Detects 16 consecutive negative current limit events to trigger hiccup mode, ensuring reliable recovery after secondary short circuits. |
| Programmable EN/UVLO | Resistor divider on EN/UVLO sets precise input turn-on voltage (e.g., 17V for 24V systems), preventing brownout operation. |
| All-ceramic capacitor support | Compatible with X7R ceramics on input, output, and VCC-enabling compact, high-reliability layouts without electrolytics. |
Applications
| Isolated Fieldbus Interfaces | PLC I/O Modules |
|---|---|
Use Scenario: Providing galvanically isolated 5V/24V bias to RS-485 transceivers and signal conditioners in factory automation networks. IC Role / Device Role / Timing Role: Primary-side regulated iso-buck controller generating isolated VPRI, scaled via transformer to deliver clean, regulated secondary rails. Use Value: Eliminates optocoupler and external LDO, reducing component count by ≥3 while maintaining ±1.7% output accuracy across -40°C to +125°C. |
Use Scenario: Powering isolated analog input channels (e.g., 4–20mA receivers) and digital output drivers in modular PLC backplanes. IC Role / Device Role / Timing Role: High-efficiency DC-DC controller delivering 5W isolated power with hiccup-mode protection against field-wiring faults. Use Value: Withstands continuous short-circuit on secondary side (via MAX17681A's 16-event detection), enabling fail-safe operation without system reset. |
| Smart Meters | Isolated Medical Power Supplies |
Use Scenario: Generating isolated auxiliary power for metrology ADCs, RF modules, and secure MCU subsystems in ANSI C12.20-compliant meters. IC Role / Device Role / Timing Role: Compact iso-buck controller operating from wide-input utility supply (e.g., 9–42V DC bus) with low shutdown current (0.9μA). Use Value: Enables >10-year battery backup life in tamper-detection circuits due to ultra-low quiescent current and no optocoupler leakage path. |
Use Scenario: Providing reinforced isolation for patient-connected sensors and diagnostic front-ends in Class II medical equipment per IEC 60601-1. IC Role / Device Role / Timing Role: Isolated DC-DC controller meeting creepage/clearance requirements via transformer-based barrier, not IC-integrated isolation. Use Value: Supports 5kVRMS isolation (via external transformer) while maintaining ±1.7% regulation and thermal shutdown at 165°C for safety-critical operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar iso-buck DC-DC controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX17681TBA+ | Same pinout and electrical specs, but lacks secondary-side overcurrent protection logic; only provides primary OCP and hiccup on runaway current or VPRI undervoltage. | Suitable for designs where secondary fault detection is handled externally or where secondary short-circuit risk is negligible. | Select MAX17681TBA+ only if secondary OCP is unnecessary and cost minimization is critical; MAX17681ATB+ is recommended for all new designs per Maxim documentation. |
| LM5160QPWPRQ1 | Automotive-grade flybuck controller (4.5V–65V), no integrated MOSFETs, requires external high-side switch; no secondary OCP scheme; uses secondary-side feedback via optocoupler or auxiliary winding. | Targets AEC-Q100 automotive systems requiring extended temperature and qualification; not drop-in compatible due to different topology and feedback method. | Choose LM5160QPWPRQ1 only for automotive applications needing ASIL-B compliance; MAX17681ATB+ offers simpler layout, higher integration, and superior secondary fault handling for industrial use. |
Compared with MAX17681TBA+, the MAX17681ATB+ adds deterministic secondary short-circuit recovery via active capacitor discharge and dual-rail soft-start. Versus LM5160QPWPRQ1, it eliminates optocouplers and external MOSFETs, reducing bill-of-materials and layout complexity while delivering tighter regulation and faster fault response in non-automotive industrial settings.
Availability
MAX17681ATB+ is available at Aetrix Electronics and suitable for isolated fieldbus interfaces, PLC I/O modules, and smart meter auxiliary power supplies requiring stable component supply, long-term lifecycle assurance, and full traceability.
Supply support for MAX17681ATB+ 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
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in high-performance analog, mixed-signal, and power management ICs for industrial, medical, and communications applications.
The MAX17681A product line delivers isolated DC-DC control without optocouplers, targeting compact, high-reliability industrial power supplies where size, efficiency, and fault resilience are critical.
FAQ
What is the key functional difference between MAX17681ATB+ and MAX17681TBA+?
The MAX17681ATB+ includes enhanced secondary-side overcurrent protection that detects 16 consecutive negative current limit events to trigger hiccup mode, actively discharges the primary capacitor, and performs coordinated soft-start of both primary and secondary outputs. The MAX17681TBA+ lacks this logic and only responds to primary-side faults. This makes MAX17681ATB+ the recommended choice for new designs requiring robust isolated output fault recovery.
Does MAX17681ATB+ require an optocoupler for isolation?
No, the MAX17681ATB+ does not require an optocoupler. It uses primary-side regulation: the FB pin monitors the primary output voltage (VPRI), and the internal control loop adjusts duty cycle to maintain regulation. Isolation is achieved entirely through the external transformer, eliminating optocoupler-related aging, bandwidth limits, and component count-confirmed in the device's General Description and Applications sections.
What is the maximum continuous output power supported by MAX17681ATB+?
The MAX17681ATB+ is rated for up to 5W of continuous isolated output power. This value is specified in the General Description and Benefits and Features sections, and is achievable with proper transformer selection, thermal management (θJA = 67.3°C/W), and layout per the recommended land pattern (90-0082). Derating applies above +70°C ambient.
How does the RESET pin function on MAX17681ATB+?
The RESET pin on MAX17681ATB+ is an open-drain output that goes low when the primary output voltage (VPRI) falls below 92.5% of its regulated value or during thermal shutdown. It returns to high-impedance state 1024 switching cycles after VPRI rises above 95.5%. This provides a delayed, glitch-immune power-good signal usable for system sequencing or fault indication-verified in the Electrical Characteristics and Detailed Description sections.
What package type and dimensions does MAX17681ATB+ use?
The MAX17681ATB+ uses a 10-pin TDFN package measuring 3mm × 2mm with an exposed pad (EP) connected to GND. This is confirmed in the Package Information section, Outline Number 21-0429, Land Pattern Number 90-0082, and Pin Configuration diagram. The exposed pad must be soldered to a large copper plane for thermal performance.
MAX17681ATB+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Strip
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.9V
- Voltage - Output (Max):
- 40.32V
- Current - Output:
- -
- Frequency - Switching:
- 200kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-TDFN (3x2)
MAX17681ATB+ FAQ
1.How can I place an order for MAX17681ATB+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX17681ATB+ 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 MAX17681ATB+ reliable?
The price and inventory of MAX17681ATB+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX17681ATB+ is usually 5 days.
3.What payment methods are accepted for MAX17681ATB+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX17681ATB+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX17681ATB+?
MAX17681ATB+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX17681ATB+ 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 MAX17681ATB+?
For technical support, including MAX17681ATB+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX17681ATB+ requirements.
6.How does Aetrix verify that MAX17681ATB+ is sourced from the original manufacturer or authorized distributors?
All MAX17681ATB+ 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 MAX17681ATB+ meets industry standards.
7.What is the process for return or replacement of MAX17681ATB+?
All MAX17681ATB+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX17681ATB+, 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 MAX17681ATB+ part is unused and in its original packaging.
Return procedure for MAX17681ATB+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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