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Analog Devices Inc./Maxim Integrated MAX17681ATB+T
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- Part No.:
- MAX17681ATB+T
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
MAX17681ATB+T.pdf
- Description:
- IC REG BUCK ADJ 10TDFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,885
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Product details
Overview
MAX17681ATB+T from Maxim Integrated is a high-voltage, primary-side regulated iso-buck DC-DC converter 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 targets industrial isolated power rails in PLC I/O modules and smart meters.
For engineers reviewing the MAX17681ATB+T datasheet, MAX17681ATB+T pinout, MAX17681ATB+T application, or MAX17681ATB+T equivalent, key selection criteria include primary-side overcurrent protection, secondary-side hiccup recovery (enhanced in MAX17681A), ±1.7% feedback accuracy, programmable EN/UVLO threshold, and thermal shutdown at +165°C.
Technical Context
The MAX17681ATB+T implements peak-current-mode control with internal transconductance amplifier (GM = 590μS typ) and cycle-by-cycle current limiting (IPEAK-LIMIT = 1.65A typ). Its synchronous buck topology uses primary-side feedback via FB pin referenced to 0.9V regulation voltage, eliminating optocouplers and enabling compact isolated designs.
It integrates an internal 5V LDO (VCC) capable of sourcing 40mA, supports adjustable soft-start (ISS = 5μA typ), and features open-drain RESET with 92.5%–95.5% FB threshold hysteresis. The device enters hiccup mode after runaway current limit (1.7A typ) or VPRI undervoltage (71.14% of nominal), with active primary capacitor discharge during timeout for robust secondary-side fault recovery-exclusive to the MAX17681A variant.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 42V - supports wide industrial bus voltages including 24V and 36V systems without external pre-regulation. |
| Output Power | Up to 5W - sufficient for isolated fieldbus interfaces, PLC digital I/O, and medical auxiliary rails. |
| Peak Efficiency | >90% - achieved via low RDS-ON MOSFETs (0.55Ω HS / 0.2Ω LS) and synchronous operation, reducing thermal load. |
| Feedback Accuracy | ±1.7% - ensures tight primary output regulation critical for stable secondary rail derivation via transformer turns ratio. |
| Switching Frequency | 200kHz (typ) - balances EMI performance and magnetics size; fixed-frequency operation simplifies filter design. |
| Shutdown Current | 0.9μA (typ) - enables ultra-low-power standby in battery-backed or energy-sensitive applications. |
| Operating Temperature | −40°C to +125°C - qualified for harsh industrial environments including motor control cabinets and outdoor metering. |
Pinout & Package
MAX17681ATB+T is housed in a 10-pin, 3mm × 2mm TDFN package with exposed pad (EP) thermally connected to GND. The compact footprint supports high-density PCB layouts in space-constrained isolation barriers.
| 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 capacitor. |
| 2 VIN | Input Supply | Accepts 4.5V–42V; requires X7R ceramic bypass capacitor to PGND for EMI suppression and transient current delivery. |
| 3 EN/UVLO | Enable / Input UVLO Input | Active-high logic input; resistor divider from VIN sets turn-on threshold (1.218V typ rising); pulling low disables all circuitry and reduces IIN to 0.9μA. |
| 4 VCC | Internal LDO Output | 5V (4.65–5.35V) regulated supply for internal blocks and low-side gate driver; bypassed with ≥1μF ceramic to GND. |
| 5 FB | Feedback Input | Monitors primary output via resistor divider; regulates VPRI to 0.9V reference (0.884–0.916V); ±1.7% accuracy enables precise secondary rail scaling. |
| 6 SS | Soft-Start Control | 5μA current source charges external capacitor; controls monotonic VPRI ramp-up to limit inrush current and prevent transformer saturation. |
| 7 COMP | Compensation Node | Connects external RC network to stabilize peak-current-mode loop; transconductance amplifier (590μS typ) enables simple Type II compensation. |
| 8 RESET | Open-Drain Reset Output | Pulls low when FB drops below 92.5% of setpoint; goes high-impedance 1024 cycles after FB rises above 95.5%; indicates valid primary regulation. |
| 9 GND | Signal Ground | Reference for analog circuits (FB, COMP, SS); must be connected to PGND at single-point star ground near VCC capacitor. |
| 10 LX | Switching Node | Connects to primary winding of isolation transformer; high-impedance in shutdown; handles ±1.6A RMS current and fast voltage transitions. |
Key Features
| Feature | Design Value |
|---|---|
| No optocoupler required | Primary-side regulation eliminates optocoupler, reducing BOM cost, board area, and long-term reliability risk from LED aging. |
| Synchronous primary operation | Integrated high-side pMOS and low-side nMOS switches enable >90% efficiency and eliminate external diode losses. |
| All-ceramic capacitor support | Stable operation with X7R ceramics on input, output, and VCC improves lifetime and temperature stability vs. electrolytics. |
| Robust secondary-side hiccup recovery | MAX17681A-specific logic discharges primary capacitor during hiccup timeout and soft-starts both primary and secondary outputs after fault removal. |
| Programmable EN/UVLO threshold | Resistor divider sets precise turn-on voltage (e.g., 18V or 28V), preventing operation during brownout or cold-cranking conditions. |
Applications
| Isolated Fieldbus Interfaces | PLC I/O Modules |
|---|---|
Use Scenario: Providing galvanically isolated 5V/3.3V rails for RS-485 transceivers and digital isolators in factory automation networks. IC Role / Device Role / Timing Role: Primary-side regulated iso-buck controller generating clean, stable isolated power directly from 24V DC bus. Use Value: Eliminates need for separate isolated DC-DC modules, reducing solution size by >40% and removing optocoupler drift concerns. |
Use Scenario: Powering isolated analog input channels, relay drivers, and status LEDs in modular programmable logic controllers. IC Role / Device Role / Timing Role: High-efficiency isolated power source delivering up to 5W across reinforced insulation barrier per channel group. Use Value: Enables compact, convection-cooled module designs meeting IEC 61000-4-5 surge immunity and UL 61010 creepage requirements. |
| Smart Meters | Isolated Power Supplies in Medical Equipment |
Use Scenario: Generating isolated 3.3V for metrology ADCs and 5V for RF communication ICs in ANSI C12.20-compliant electricity meters. IC Role / Device Role / Timing Role: Single-chip isolated DC-DC converter meeting stringent low-noise and long-term stability requirements for revenue-grade measurement. Use Value: Achieves <±0.1% output drift over 10-year life via ceramic-only design and ±1.7% FB accuracy-no calibration needed. |
Use Scenario: Supplying isolated auxiliary power for patient-connected sensors and microcontroller subsystems in Class II medical devices. IC Role / Device Role / Timing Role: Reinforced-isolation power controller compliant with IEC 60601-1 2×MOPP requirements when paired with certified transformer. Use Value: Supports 2500VRMS isolation rating and −40°C to +125°C operation, enabling reliable use in portable ultrasound and infusion pumps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar iso-buck DC-DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX17681TBA+T | Base variant without enhanced secondary-side hiccup recovery; supports only primary-side OCP and basic hiccup on VPRI undervoltage. | Limited to applications where secondary short-circuit events are rare or externally managed; not recommended for new designs requiring robust fault recovery. | Select MAX17681ATB+T when secondary-side fault resilience is required; MAX17681TBA+T may be used only if legacy compatibility or cost sensitivity outweighs hiccup robustness. |
| LM5160QPWPRQ1 | Automotive-qualified flyback controller (AEC-Q100 Grade 1); requires external MOSFETs, optocoupler, and TL431; no integrated switches or primary-side regulation. | Targets automotive body electronics with 4.5V–65V input; lacks integrated isolation transformer drive and secondary hiccup logic. | Choose LM5160QPWPRQ1 only for AEC-Q100 compliance needs; MAX17681ATB+T offers smaller solution size, higher integration, and superior secondary fault handling for industrial use. |
Compared with MAX17681TBA+T, MAX17681ATB+T adds deterministic 16-cycle negative-current-triggered hiccup and active primary capacitor discharge-critical for reliable recovery after secondary shorts. Versus LM5160QPWPRQ1, it delivers full integration (switches, regulation, hiccup logic) in a 3mm × 2mm package, reducing component count by >12 and eliminating optocoupler calibration drift.
Availability
MAX17681ATB+T is available at Aetrix Electronics and suitable for PLC I/O modules, smart meters, and isolated fieldbus interfaces requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for MAX17681ATB+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
Maxim Integrated, now part of Analog Devices, designs precision analog, mixed-signal, and power management ICs for industrial, automotive, and communications markets.
The MAX17681 series targets isolated low-power DC-DC conversion in space- and reliability-constrained industrial systems, emphasizing primary-side regulation, integrated MOSFETs, and robust fault recovery without optocouplers.
FAQ
What is the key functional difference between MAX17681ATB+T and MAX17681TBA+T?
The MAX17681ATB+T implements enhanced secondary-side overcurrent protection absent in MAX17681TBA+T. Specifically, MAX17681ATB+T enters hiccup mode after 16 consecutive negative current limit events-enabling reliable recovery from secondary short circuits. It also actively discharges the primary capacitor during hiccup timeout and soft-starts both primary and secondary outputs upon recovery. This behavior is confirmed in the MAX17681A datasheet revision and applies exclusively to MAX17681ATB+T.
Does MAX17681ATB+T require an optocoupler for isolation?
No, MAX17681ATB+T does not require an optocoupler. It uses primary-side feedback regulation via the FB pin and internal 0.9V reference to control the primary output voltage, which is then scaled to the desired secondary output via transformer turns ratio. This architecture eliminates optocoupler-related drift, aging, and layout complexity-confirmed in the General Description and Benefits sections of the official datasheet.
What is the maximum continuous output power supported by MAX17681ATB+T?
MAX17681ATB+T supports up to 5W of continuous isolated output power, as specified in the General Description, Applications, and Electrical Characteristics sections. This rating assumes proper thermal design (e.g., adequate copper pour under EP pad), operation within the −40°C to +125°C ambient range, and use of recommended external components (X7R ceramics, appropriate transformer).
How is the soft-start time programmed on MAX17681ATB+T?
The soft-start time on MAX17681ATB+T is set by an external capacitor connected from the SS pin to GND. A 5μA internal current source charges this capacitor; soft-start duration (tSS in ms) equals 5.55 × CSS (in nF). For example, a 3300pF capacitor yields ~18.3ms soft-start. This relationship is defined in the Applications Information section and validated in Figure 9's timing waveforms.
What protection features are included in MAX17681ATB+T?
MAX17681ATB+T includes peak current-limit (1.65A typ), runaway current-limit (1.7A typ), sink current-limit (1.25A typ), thermal shutdown (+165°C with 10°C hysteresis), output undervoltage hiccup (71.14% VPRI), and open-drain RESET with 92.5%/95.5% FB thresholds. Crucially, its MAX17681A variant adds 16-cycle negative-current-triggered hiccup and active primary capacitor discharge-detailed in the Overcurrent Protection/HICCUP Mode section.
MAX17681ATB+T Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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+T FAQ
1.How can I place an order for MAX17681ATB+T through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX17681ATB+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 MAX17681ATB+T reliable?
The price and inventory of MAX17681ATB+T are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX17681ATB+T is usually 5 days.
3.What payment methods are accepted for MAX17681ATB+T?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX17681ATB+T transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX17681ATB+T?
MAX17681ATB+T orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX17681ATB+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 MAX17681ATB+T?
For technical support, including MAX17681ATB+T datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX17681ATB+T requirements.
6.How does Aetrix verify that MAX17681ATB+T is sourced from the original manufacturer or authorized distributors?
All MAX17681ATB+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 MAX17681ATB+T meets industry standards.
7.What is the process for return or replacement of MAX17681ATB+T?
All MAX17681ATB+T units undergo pre-shipment inspection (PSI). If there is an issue with MAX17681ATB+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 MAX17681ATB+T part is unused and in its original packaging.
Return procedure for MAX17681ATB+T:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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