feature

Equivalent™ Circuit Construction; Insulation Test Voltage: to 3.5kV rms; Five Independent Logic Lines: Six I/O Configurations; Logic Signal Bandwidth: 20 MHz (min), 40 Mbps (NRZ); Isolated Power Transformer: 37 V pp, 1.5 W max; CMV Transient Immunity: 10kv/min ms; Waveform Edge Transfer Symmetry: 61 ns; Field and System Output Enable/Tri-State Capability; Performance Level Over -258C to + 858C; UL1950, IEC950, EN60950 certification, pending.

application

PLC/DCS analog input and output card; communication bus isolation; general data acquisition applications; IGBT motor drive control; high-speed digital I/O ports.

General Instructions

The AD260 uses an analog device design and uses a new isolation circuit structure to isolate the five digital control signals from the microcontroller and its associated field I/O components. Six models allow all I/O combinations from five input lines to five output lines, including combinations in between. Each AD260 effectively replaces up to 5 opto-isolators while also providing a 1.5W transformer for the 3.5kV isolated DC power circuit.

Each row of the AD260 has a bandwidth of 20 MHz (min) and its propagation delay is only 14 ns, which allows extremely fast data transfer. The output waveform symmetry is maintained within ±1ns of the input, so time-based PWM signals can be precisely isolated using the AD260.

All field or system output pins of the AD260 can be set to high-resistance tri-state levels using two enable pins. The described field output 3 provides a convenient way to preset logic levels at power up using up/down resistors. The system-side output is three states allowing simple multiplexing of multiple AD260s.

AD260 Class B isolation barrier is 100% tested at 3.5kV rms (system to field). The barrier design also provides good common-mode transient immunity, allowing the field-side terminals to drift within 10 kV/µs relative to the system-side common-mode voltage, with no false output triggering on either side.

Each output is updated with input logic transitions in nanoseconds, and the AD260 also features continuous output updates, according to

enter. This guarantees that the output is always active for 10 microseconds after a fault condition or after a power-on reset interval.

The AD260 also has an integrated center-tapped transformer for isolated power generation. Typically driven by a 5 V push-pull driver on the primary side, it will produce a 37 V pp output capable of delivering up to 1.5 W. It can then be regulated to the desired voltage, including ±5 V dc for circuit components and 24 V for 20 mA loop power (if needed).

Product Highlights

Six Independent Logic Line I/O Configurations Available: The AD260 is available in six-pin compatible I/O configurations to meet a variety of needs.

Wide Bandwidth with Minimal Edge Error: The AD260 and IsoLogic provide very fast logic signal isolation due to their 20mhz bandwidth and 14ns propagation delay. It maintains waveform input and output edge transition errors typically less than ±1ns (total) for positive and negative transitions.

3.5kV rms Test Voltage Isolation Rating: AD260 Class B rated working voltage is 1.25kV rms and is 100% production tested at 3.5kV rms using standard ADI test methods.

High Transient Immunity: The AD260 rejects common-mode transients spinning at speeds up to 10 kV/µs without false triggering or damage to the device.

Integral Isolated Power Supply: The AD260 includes an integrated, uncommitted and flexible 1-watt power transformer for developing isolated field power.

Field and system enable functions: The AD260 has enable pins on both the isolated and non-isolated sides that tri-state all outputs. When these pins are re-enabled, all outputs will be updated to reflect the current input logic level.

CE Marking: By adding external bypass capacitors at the power pins, the AD260 can be CE marked (in compliance with the EMC Directive) in most applications, and compliance with the Low Voltage (Safety) Directive is guaranteed by EN60950 certification.

Absolute Maximum Ratings*

*Stresses above the Absolute Maximum Ratings may cause permanent damage to the device. This is a pressure rating only; functional operation of the equipment under the above or any other conditions stated in the operating section of this specification is not implied. Exposure to absolute maximum rating cycles may affect device reliability.

Available I/O Configurations

The AD260 is available in a variety of configurations. The choice of model is determined by the number of inputs and outputs required. The power and make pins are always in the same location on all models.

*The function of the pin depends on the model. See Table 1.

NOTE: Be careful when handling the unit as contamination on the bottom of the unit or on the circuit card on which the unit is mounted can reduce the isolation barrier breakdown voltage.

Pin configuration

General properties

AD260 provides five HCMOS/ACMOS compatible isolated logic lines with common mode transient immunity ≥10kV/µs. The housing design and pinout provide greater than 18 mm spacing between field and system side conductors, providing CSA/IS and IEC creepage clearances compliant with 750 V power isolation.

Five unidirectional logic lines have six possible "input" and "output" combinations, or transmitter/receiver pairs; thus there are six AD260 part configurations (see Table 1).

Each 20mhz logic line has a Schmitt trigger input and a tri-state output (on the other side of the isolation barrier) and a 14ns propagation delay. An enable pin on either side of the barrier puts all outputs on that side into three states, all inputs (drive pins) ignore their inputs and retain their last known state.

NOTE: All unused logic inputs (1-5) should be high or low, but not left floating.

Edge "fidelity", which is the difference in propagation time between rising and falling edges, is typically less than ±1ns.

Unlike opto-isolators, power consumption is a function of operating frequency. Each logic line barrier driver requires about 160 microamps per megahertz, and each receiver requires 40 microamps per megahertz, plus, of course, 4 milliamps of total idle current (each side). The supply current decreases slightly with increasing temperature (about -0.03%/°C).

The total capacitance across the isolation barrier is less than 10 lbf.

The minimum width of a pulse that can be precisely coupled through the barrier is about 25ns. Therefore, the maximum square wave frequency for operation is 20 MHz.

Logic information is sent through the barrier as "set hi/set lo" data, which comes from the input's logic-level transitions. At power-up or after a fault condition, the outputs may not represent the state of the individual channel inputs to the isolator. The internal circuitry works in the background, which interrogates all inputs approximately every 5 microseconds, and sends the appropriate "set hi" or "set lo" data through the barrier without logical transitions.

Therefore, the recovery time from a fault state or upon power-up is between 5 and 10 microseconds.

The power transformer is designed to operate between 150 9251 ; kHz and 250 kHz and can easily provide more than 1W of isolated power when driving push-pull (5V) on the system side. Different transformer taps, rectifiers and regulator schemes will provide combinations of ±5 V, 15␣V, 24␣V and even 30V or higher.

When driven with a low voltage drop drive (@5v push-pull), the output voltage across the secondary side will be 37v pp. At 4.5 V drive, the voltage will drop to 33 V pp.

Applications

The following are examples of typical transformer system-side drive circuits and field-side regulation circuits suitable for most general applications.

Dimensions: Dimensions are in inches and (mm).

22 Lead Plastic Impregnation (ND-22)