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Analog Devices Inc./Maxim Integrated MAX22518AWA+
- Part No.:
- MAX22518AWA+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Digital Isolators
- Package:
- 8-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
MAX22518AWA+.pdf
- Description:
- DUAL CHANNEL DIGITAL ISOLATOR WI
- Quantity:
- Payment:
- Shipping:
Inventory:2,483
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Product details
Overview
MAX22518AWA+ from Analog Devices is a self-powered, dual-channel digital galvanic isolator with integrated isolated DC-DC converter, 3.5kVRMS withstand voltage (60s), ±2kV common-mode surge tolerance, and open-drain logic-side outputs. It transfers field-side input states unidirectionally to the logic side for relay contact monitoring in industrial control systems.
For engineers reviewing the MAX22518AWA+ datasheet, MAX22518AWA+ pinout, MAX22518AWA+ application, or MAX22518AWA+ equivalent, key selection considerations include its 220μA field-side supply capability, 1Mbps data rate, -40°C to +125°C operation, and 8-pin wide-body SOIC package with 5.5mm creepage.
Technical Context
The MAX22518AWA+ implements capacitive isolation with an integrated 750MHz switching DC-DC converter that generates VDDF (nominal 3.3V) from VDDL (3.0–5.5V), enabling field-side power without external isolation. Its input charge pump delivers 5.25V boost voltage and 5μA current per channel to clean relay contacts.
Both channels are unidirectional (field-to-logic), always enabled, and feature open-drain outputs requiring external pullup resistors to VDDL. Output default state is high-impedance during undervoltage on either VDDL (UVLO threshold 2.82V typ) or VDDF (UVLO threshold 2.1V typ).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Isolation Withstand Voltage | 3.5kVRMS for 60s - meets UL1577 basic insulation requirements for industrial safety-critical interfaces |
| Continuous Working Voltage | 445VRMS - supports long-term operation in 24VAC field environments with continuous short protection |
| Surge Tolerance | ±2kV line-to-line (1.2/50μs), ±1kV line-to-ground - enables robust relay monitoring without external TVS diodes when using ≥10kΩ series resistors |
| Field-Side Supply Capability | 220μA at <100kbps - powers external window comparators or auxiliary field-side circuitry without isolated DC/DC module |
| Data Rate | 1Mbps - supports fast status updates for real-time industrial I/O monitoring |
| Propagation Delay | 80–130ns - ensures deterministic timing for time-sensitive PLC input scanning |
| Common-Mode Transient Immunity | 50kV/μs - maintains signal integrity in noisy motor drive or solenoid switching environments |
Pinout & Package
MAX22518AWA+ uses an 8-pin wide-body SOIC package (W8MS+1 outline) with 5.5mm creepage and clearance, CTI ≥400 (Group II), and RoHS-compliant finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN1F / IN2F | Field-side digital inputs | Accept 24VAC field signals; internal charge pump provides 5.25V/5μA per channel for relay contact cleaning |
| VDDF | Isolated field-side supply output | Nominal 3.3V regulated output; powers internal circuitry and up to 220μA external load |
| GNDF | Field-side ground reference | Galvanically isolated return path for field-side circuits; must not be connected to GNDL |
| GNDL | Logic-side ground reference | Return for VDDL and logic outputs; forms isolation barrier boundary with GNDF |
| VDDL | Logic-side supply input | 3.0–5.5V single supply powering both logic side and isolated DC-DC converter |
| OUT1L / OUT2L | Open-drain logic outputs | Require external pullup to VDDL; default to high-impedance during UVLO or open-circuit input |
Key Features
| Feature | Design Value |
|---|---|
| Integrated isolated DC-DC converter | Eliminates need for external isolated power supply in low-power field-side applications (<220μA) |
| Input charge pump with boost voltage | 5.25V/5μA per channel enables reliable relay contact detection by removing oxidation residue |
| Robust transient immunity | ±2kV common-mode surge tolerance with only 10kΩ series resistor per input - reduces BOM count |
| High CMTI | 50kV/μs common-mode transient immunity prevents false triggering in EMI-heavy factory floors |
| Wide temperature range | -40°C to +125°C operation supports deployment in uncontrolled industrial enclosures and outdoor cabinets |
Applications
| Relay Contact Monitoring | PLC Digital Input Module |
|---|---|
Use Scenario: Continuous monitoring of electromechanical relay status in HVAC control panels where contact oxidation causes false-open readings. IC Role / Device Role / Timing Role: Field-side inputs sense relay closure via charge-pump–assisted wetting current; logic-side open-drain outputs interface directly to microcontroller GPIOs. Use Value: Eliminates manual relay maintenance cycles by ensuring reliable detection of closed contacts even after years of intermittent use. | Use Scenario: Isolated 24VDC digital input channel in modular PLC backplanes exposed to motor drive noise and ground potential differences. IC Role / Device Role / Timing Role: Provides galvanic separation between field wiring and controller logic; 1Mbps data rate supports high-speed I/O scanning cycles. Use Value: Prevents ground-loop induced errors and protects controller from 24VAC shorts and ±2kV surges without discrete protection components. |
| Industrial IoT Sensor Hub | Building Automation Gateway |
Use Scenario: Aggregating status signals from multiple legacy 24VAC sensors (e.g., door switches, occupancy detectors) into a wireless edge node. IC Role / Device Role / Timing Role: Self-powered field-side interface converts analog/voltage-based sensor states into clean logic-level signals for MCU processing. Use Value: Reduces system power budget by eliminating isolated DC/DC converters per channel while maintaining safety certification. | Use Scenario: Interfacing fire alarm panel dry-contact outputs to a BACnet/IP gateway operating from a shared 3.3V rail. IC Role / Device Role / Timing Role: Provides certified 3.5kVRMS isolation between life-safety field wiring and Ethernet-connected logic domain. Use Value: Meets UL/cUL 1577 requirements for Class 2 circuits while enabling compact, fanless gateway design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digital isolator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX22517AWA+ | Push-pull outputs with logic-high default; no external pullup required; lacks field-side load capability beyond internal circuitry | Better suited for direct MCU interface without pullup resistors; less suitable for driving LEDs or higher-current loads | Select MAX22517AWA+ when output loading is light and default-high behavior is preferred during power loss |
| ISO6721DWR | 2-channel, 5000VRMS reinforced isolation; requires external isolated supply; no integrated field-side power or charge pump | Higher isolation rating for medical or safety-critical systems; no relay contact cleaning capability | Select ISO6721DWR when regulatory requirements demand reinforced insulation or field-side power is already available |
Compared with MAX22517AWA+, the MAX22518AWA+ offers safer default state (high-Z vs. high) during undervoltage and supports external field-side loads, while ISO6721DWR trades integrated power for higher isolation rating but adds system-level complexity.
Availability
MAX22518AWA+ is available at Aetrix Electronics and suitable for industrial IoT gateways, PLC digital input modules, and building automation controllers requiring stable component supply across extended temperature ranges and safety-certified isolation.
Supply support for MAX22518AWA+ 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.
The MAX22517–MAX22519 family was designed specifically for cost-sensitive, space-constrained industrial field interfaces requiring self-powered isolation, relay contact monitoring, and integrated surge protection - eliminating external power and protection components.
FAQ
What is the function of the charge pump in MAX22518AWA+?
The charge pump in MAX22518AWA+ generates a 5.25V boost voltage and supplies ~5μA per input to clean oxidation from relay contacts during closure. This wetting current ensures reliable detection of mechanically aged relays in industrial control systems, and is a core differentiator versus standard digital isolators without this feature. The MAX22518AWA+ leverages this capability to maintain accuracy over decades of intermittent operation.
Does MAX22518AWA+ require an external isolated power supply?
No, MAX22518AWA+ does not require an external isolated power supply. Its integrated DC-DC converter derives VDDF (3.3V nominal) from the single 3.0–5.5V VDDL logic-side supply, delivering up to 220μA to power external field-side circuitry such as window comparators. This eliminates BOM cost and board space associated with discrete isolated DC/DC modules while maintaining UL1577 certification.
What is the default output state of MAX22518AWA+ during power loss?
The default output state of MAX22518AWA+ is high-impedance during undervoltage on either VDDL or VDDF, or when inputs are open-circuited. This safe default prevents false logic assertions to downstream controllers during brownouts or field-side power failure. Unlike push-pull variants (e.g., MAX22517AWA+), the open-drain architecture of MAX22518AWA+ ensures no unintended current paths form during fault conditions.
How does MAX22518AWA+ achieve ±2kV surge protection without external components?
MAX22518AWA+ achieves ±2kV line-to-line surge tolerance (IEC 61000-4-5, 1.2/50μs) using only a 10kΩ series resistor per input, enabled by internal robust input structures and field-side charge pump clamping. The device's 5.5mm creepage package and integrated protection eliminate the need for external TVS diodes or transient suppressors in most industrial 24VAC applications, reducing bill-of-materials and layout complexity.
Can MAX22518AWA+ operate with 24VAC field inputs?
Yes, MAX22518AWA+ supports continuous 24VAC input shorts on IN1F/IN2F when used with ≥10kΩ series resistors. Its input structure tolerates -60V to +60V with series resistance, and the internal charge pump provides sufficient wetting current to ensure reliable relay contact detection even under AC-coupled field conditions. This makes MAX22518AWA+ suitable for legacy industrial systems using AC-powered sensors and switches.
MAX22518AWA+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 8-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tray
- Product Status:
- Active
- Technology:
- Capacitive Coupling
- Type:
- General Purpose
- Isolated Power:
- No
- Number of Channels:
- 2
- Inputs - Side 1/Side 2:
- 2/0
- Channel Type:
- Unidirectional
- Voltage - Isolation:
- 3500Vrms
- Common Mode Transient Immunity (Min):
- 50kV/µs (Typ)
- Data Rate:
- 1Mbps
- Propagation Delay tpLH / tpHL (Max):
- 130ns, 130ns
- Pulse Width Distortion (Max):
- 20ns
- Rise / Fall Time (Typ):
- 20ns, 20ns
- Voltage - Supply:
- 3V ~ 5.5V
- Grade:
- -
- Qualification:
- -
- Operating Temperature:
- -40°C ~ 125°C
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
MAX22518AWA+ FAQ
1.How can I place an order for MAX22518AWA+ through Aetrix?
Please submit a Request for Quotation (RFQ) for MAX22518AWA+ 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 MAX22518AWA+ reliable?
The price and inventory of MAX22518AWA+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MAX22518AWA+ is usually 5 days.
3.What payment methods are accepted for MAX22518AWA+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MAX22518AWA+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MAX22518AWA+?
MAX22518AWA+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MAX22518AWA+ 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 MAX22518AWA+?
For technical support, including MAX22518AWA+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MAX22518AWA+ requirements.
6.How does Aetrix verify that MAX22518AWA+ is sourced from the original manufacturer or authorized distributors?
All MAX22518AWA+ 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 MAX22518AWA+ meets industry standards.
7.What is the process for return or replacement of MAX22518AWA+?
All MAX22518AWA+ units undergo pre-shipment inspection (PSI). If there is an issue with MAX22518AWA+, 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 MAX22518AWA+ part is unused and in its original packaging.
Return procedure for MAX22518AWA+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
MAX22518AWA+ Tags
-
ISO1212DBQR
Texas Instruments
-
ISO6721BDR
Texas Instruments
-
SI8710AC-B-ISR
Skyworks Solutions Inc.
-
ISO7720FDR
Texas Instruments
-
ISO7721DR
Texas Instruments
-
ISO7721FDR
Texas Instruments
-
SI8710CC-B-ISR
Skyworks Solutions Inc.
-
ISO6741FQDWRQ1
Texas Instruments
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ISO7721DWVR
Texas Instruments
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ISO7762FDBQR
Texas Instruments
-
ISO7741DWR
Texas Instruments
-
ISO7741FDWR
Texas Instruments
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