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Home > Products > Isolators > Digital Isolators

Analog Devices Inc. AD261BND-4

Name: AD261BND-4
Brand: Analog Devices Inc.
SKU: AD261BND-4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: AD261BND-4

Manufacturer:: Analog Devices Inc.

Category:: Digital Isolators

Package:: 22-DIP Module

Datasheet:: AD261BND-4.pdf

Description:: DGTL ISO 3.5KV GEN PURP 22DIP

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Product details

Overview

AD261BND-4 from Analog Devices is a high-speed logic isolator with 4 field-side inputs and 1 system-side output, rated for 3.5 kV_rms isolation, 20 MHz bandwidth, and 14 ns propagation delay. It replaces up to five opto-isolators in PLC analog I/O cards and IGBT motor drive controls where precise PWM signal integrity and fast edge transmission are required.

For engineers reviewing the AD261BND-4 datasheet, AD261BND-4 pinout, AD261BND-4 application, or AD261BND-4 equivalent, key selection criteria include its 4-input/1-output configuration, field/system enable-controlled three-state outputs, ±1 ns waveform edge symmetry, and VDE/EN60950-certified 3.5 kV_rms isolation barrier tested at production level.

Technical Context

The AD261BND-4 implements five unidirectional HCMOS-compatible logic channels across a capacitive isolation barrier, with each channel featuring a Schmitt-trigger input and transparent latch-based output stage. Its continuous update circuit ensures output validity within 12 µs after power-up reset or fault recovery by sampling inputs every ~5 µs.

Isolation is achieved via a 22-pin plastic DIP (ND-22A) package with ≥18 mm creepage between field and system sides, supporting intrinsic safety up to 750 V mains. The device operates over –25°C to +85°C with dual 4.5–5.5 V supplies and delivers 10 kV/µs common-mode transient immunity without false triggering.

Key Specifications

Parameter	Value and Actual Design Meaning
Isolation Rating	3.5 kV_rms production-tested (VDE/EN60950 compliant); enables safe interface between 750 V mains-referenced field circuits and low-voltage control systems.
Signal Bandwidth	20 MHz minimum; supports accurate isolation of fast digital signals including PWM with ≤25 ns minimum pulse width.
Propagation Delay	14 ns typical; ensures sub-25 ns timing alignment critical for synchronous I/O in motor drives and data acquisition.
Edge Symmetry Error	±1 ns max (t_PHL vs t_PLH); preserves duty cycle fidelity essential for closed-loop PWM control loops.
Common-Mode Transient Immunity	10 kV/µs minimum; prevents false triggering during high-dv/dt events in industrial noise environments like VFDs and relay switching.
Supply Voltage Range	4.5 V to 5.5 V (rated), 4.0 V to 5.75 V (operating); compatible with standard 5 V logic rails and tolerant of supply ripple.
Quiescent Current	4 mA per side (8 mA total); enables low-power standby operation without sacrificing isolation performance.

Pinout & Package

AD261BND-4 uses a 22-pin plastic DIP package (ND-22A) with 0.100" lead pitch, 18 mm minimum creepage between field and system sides, and CSA/IEC-compliant spacing for 750 V mains isolation.

Pin	Circuit Role	Design Meaning
1–4	S0–S3 (System Inputs)	Four system-side digital inputs accepting HCMOS logic levels; configured as receivers in AD261BND-4 per Table I.
5	S4 (System Input)	Unused system-side input pin; must be tied high or low-not left floating-to prevent undefined behavior.
6	ENABLESYS	Three-states all system-side outputs (F0–F4); allows multiplexing of multiple AD261 units on shared bus lines.
7	+5 V_dcSYS	System-side 5 V power supply input; requires local 0.01 µF bypass capacitor for stable high-speed operation.
8	5 V RTNSYS	System-side ground reference; separate from field-side return to maintain isolation integrity.
15	5 V RTNFLD	Field-side ground reference; galvanically isolated from system return to block ground loop currents.
16	+5 V_dcFLD	Field-side 5 V power supply input; decoupled independently to suppress field-side noise coupling.
17	ENABLEFLD	Three-states all field-side outputs (S0–S4); enables safe power-up sequencing with pull-up/down resistors.
18–22	F0–F4 (Field Outputs)	Five field-side outputs; in AD261BND-4, only F0 is active as output-F1–F4 are unused and must be left unconnected.

Key Features

Feature	Design Value
4-Input / 1-Output Configuration	Optimized for sensor-to-controller signal routing where multiple field sensors feed a single system controller input, reducing component count vs. discrete isolators.
Continuous Output Update	Guarantees valid output state within 12 µs after power-up or fault recovery-even with no input transitions-by background polling every ~5 µs.
Dual Enable Control	Independent ENABLESYS and ENABLEFLD pins allow selective three-state control of either side's outputs, enabling flexible bus arbitration and safe hot-plug operation.
High CMV Immunity	10 kV/µs transient rejection prevents false triggering during rapid voltage transients in motor drives, relay banks, and industrial power electronics.
HCMOS-Compatible I/O	Supports direct interfacing with standard 5 V microcontrollers and FPGA I/O without level-shifting, with 2.0–3.15 V input thresholds and <5 pF input capacitance.

Applications

PLC Analog Input Cards	IGBT Motor Drive Controls
Use Scenario: Isolating 4-channel thermocouple or RTD sensor inputs from a central ADC/microcontroller in a programmable logic controller rack. IC Role / Device Role / Timing Role: Field-side sensor signal conditioner and system-side digital interface; maintains PWM timing integrity for feedback loop synchronization. Use Value: Eliminates ground loops and noise injection while preserving <±1 ns edge symmetry for accurate 20 MHz sampling clock distribution.	Use Scenario: Transmitting gate drive enable/disable signals from a system-side PWM controller to four independent IGBT half-bridges in an industrial inverter. IC Role / Device Role / Timing Role: High-speed logic isolator with deterministic 14 ns delay; synchronizes gate drive pulses across parallel power stages. Use Value: Enables precise dead-time control and prevents shoot-through by guaranteeing matched propagation delays across all four isolated channels.
Communications Bus Isolation	High-Speed Digital I/O Ports
Use Scenario: Isolating RS-485 transceiver control lines (DE/RE) and status flags between a noisy field bus segment and a clean system controller. IC Role / Device Role / Timing Role: Unidirectional logic isolator for bus direction control and fault reporting; operates at full 20 MHz data rate. Use Value: Prevents bus contention and lockup during ESD events or cable faults while maintaining real-time status visibility across isolation boundary.	Use Scenario: Providing isolated digital I/O expansion for embedded controllers in test equipment requiring simultaneous stimulus/response timing. IC Role / Device Role / Timing Role: Four independent input channels feeding one system interrupt line; supports burst-mode data capture at >10 MHz. Use Value: Reduces PCB footprint and BOM count versus five discrete optocouplers while delivering nanosecond-level timing correlation.

PLC Analog Input Cards

IGBT Motor Drive Controls

Use Scenario: Isolating 4-channel thermocouple or RTD sensor inputs from a central ADC/microcontroller in a programmable logic controller rack.

IC Role / Device Role / Timing Role: Field-side sensor signal conditioner and system-side digital interface; maintains PWM timing integrity for feedback loop synchronization.

Use Value: Eliminates ground loops and noise injection while preserving <±1 ns edge symmetry for accurate 20 MHz sampling clock distribution.

Use Scenario: Transmitting gate drive enable/disable signals from a system-side PWM controller to four independent IGBT half-bridges in an industrial inverter.

IC Role / Device Role / Timing Role: High-speed logic isolator with deterministic 14 ns delay; synchronizes gate drive pulses across parallel power stages.

Use Value: Enables precise dead-time control and prevents shoot-through by guaranteeing matched propagation delays across all four isolated channels.

Communications Bus Isolation

High-Speed Digital I/O Ports

Use Scenario: Isolating RS-485 transceiver control lines (DE/RE) and status flags between a noisy field bus segment and a clean system controller.

IC Role / Device Role / Timing Role: Unidirectional logic isolator for bus direction control and fault reporting; operates at full 20 MHz data rate.

Use Value: Prevents bus contention and lockup during ESD events or cable faults while maintaining real-time status visibility across isolation boundary.

Use Scenario: Providing isolated digital I/O expansion for embedded controllers in test equipment requiring simultaneous stimulus/response timing.

IC Role / Device Role / Timing Role: Four independent input channels feeding one system interrupt line; supports burst-mode data capture at >10 MHz.

Use Value: Reduces PCB footprint and BOM count versus five discrete optocouplers while delivering nanosecond-level timing correlation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-speed logic isolation applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Si8641ED-B-IS	4-channel, 1-output digital isolator; 5 kV_rms isolation, 150 Mbps data rate, 13 ns propagation delay; uses silicon dioxide barrier instead of capacitive coupling.	Higher speed (150 Mbps vs. 20 MHz), but lacks continuous update feature and field/system enable separation; not certified to EN60950.	Preferred when higher data throughput is needed and continuous DC-level monitoring is not required.
ISO6741FDWR	4-channel, 1-output reinforced isolator; 5 kV_rms, 50 Mbps, 11 ns delay; integrated LDO, lower quiescent current (1.5 mA/side), but only single enable pin.	Lower power and smaller SOIC-16 package; no field/system dual-enable capability or UL/IEC certification out-of-box.	Best suited for space-constrained designs where dual-enable control and safety certification are secondary to size and efficiency.

Compared with Si8641ED-B-IS and ISO6741FDWR, the AD261BND-4 uniquely combines production-tested 3.5 kV_rms isolation, dual independent enable pins, continuous output update, and EN60950 compliance-making it the only option qualified for safety-critical industrial I/O where deterministic DC-level validity and fault recovery are mandatory.

Availability

AD261BND-4 is available at Aetrix Electronics and suitable for PLC analog input cards, IGBT motor drive controls, and high-speed digital I/O ports requiring stable component supply, long-term lifecycle support, and certified isolation performance.

Supply support for AD261BND-4 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, Inc. 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 AD261 product line was designed specifically for high-noise industrial environments requiring robust, high-speed digital isolation with guaranteed DC-level validity and safety certification-targeting PLCs, motor drives, and data acquisition systems.

FAQ

What is the isolation voltage rating of the AD261BND-4?

The AD261BND-4 is rated for 1.25 kV_rms operating isolation voltage and is 100% production-tested to 3.5 kV_rms using Analog Devices' standard test method. This meets VDE and EN60950 safety requirements for industrial equipment with 750 V mains interfaces, and the isolation barrier provides ≥18 mm creepage distance between field and system sides.

How does the AD261BND-4 handle power-up and fault recovery?

The AD261BND-4 enters a power-up reset mode for ~30 µs after either supply crosses 3.3 V, disabling all outputs. Its continuous update circuit then guarantees valid output states within 12 µs after reset completion by sampling inputs every ~5 µs-even with no logic transitions-ensuring reliable startup in PLC and motor drive applications.

Can unused pins on the AD261BND-4 be left floating?

No. Per the AD261 datasheet, all unused logic inputs-including S4 on the AD261BND-4-must be tied either high or low using appropriate pull-up or pull-down resistors. Floating inputs can cause undefined output states, increased power consumption, or susceptibility to noise-induced false triggering in industrial environments.

What is the function of ENABLESYS and ENABLEFLD on the AD261BND-4?

ENABLESYS three-states all system-side outputs (F0–F4), while ENABLEFLD three-states all field-side outputs (S0–S4). In AD261BND-4, only F0 is used as output; enabling ENABLESYS places F0 in high-impedance state for bus sharing. ENABLEFLD allows presetting S0–S3 logic levels at power-up using external resistors-critical for safe IGBT gate initialization.

Does the AD261BND-4 support bidirectional communication?

No. The AD261BND-4 is strictly unidirectional: S0–S3 are system-side inputs, and F0 is the sole field-side output. All five channels are fixed-direction per model; bidirectional operation requires separate transmit/receive isolators or a different AD261 variant such as AD261BND-2 (2-in/3-out) with appropriately assigned pins.

AD261BND-4 Specifications

Product attributes: Attribute value

Manufacturer:: Analog Devices Inc.

Series:: IsoLogic™

Package/Case:: 22-DIP Module

Packaging:: Tube

Product Status:: Obsolete

Technology:: Magnetic Coupling

Type:: General Purpose

Isolated Power:: No

Number of Channels:: 5

Inputs - Side 1/Side 2:: 4/1

Channel Type:: Unidirectional

Voltage - Isolation:: 3500Vrms

Common Mode Transient Immunity (Min):: 10kV/µs

Data Rate:: -

Propagation Delay tpLH / tpHL (Max):: 25ns, 25ns

Pulse Width Distortion (Max):: -

Rise / Fall Time (Typ):: -

Voltage - Supply:: 4V ~ 5.75V

Grade:: -

Qualification:: -

Operating Temperature:: -25°C ~ 85°C

Mounting Type:: Through Hole

Supplier Device Package:: 22-PDIP

AD261BND-4 FAQ

1.How can I place an order for AD261BND-4 through Aetrix?

Please submit a Request for Quotation (RFQ) for AD261BND-4 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 AD261BND-4 reliable?

The price and inventory of AD261BND-4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD261BND-4 is usually 5 days.

3.What payment methods are accepted for AD261BND-4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD261BND-4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for AD261BND-4?

AD261BND-4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your AD261BND-4 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 AD261BND-4?

For technical support, including AD261BND-4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD261BND-4 requirements.

6.How does Aetrix verify that AD261BND-4 is sourced from the original manufacturer or authorized distributors?

All AD261BND-4 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 AD261BND-4 meets industry standards.

7.What is the process for return or replacement of AD261BND-4?

All AD261BND-4 units undergo pre-shipment inspection (PSI). If there is an issue with AD261BND-4, 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 AD261BND-4 part is unused and in its original packaging.

Return procedure for AD261BND-4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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