AD694AR - 4-20mA Current Transmitter IC | Analog Devices
MPN: AD694AR ✓ نشطAD694AR نظرة عامة
A current transmitter is an interface IC that converts a control voltage into a proportional current delivered through a two-wire process loop. This class of transmitter belongs to the hierarchy of instrumentation interface, sensor and detector interface, signal-conditioning, and industrial control ICs. The AD694AR combines an input buffer, precision reference, current-loop output stage, and open-loop alarm function to support industrial instrumentation where the controller communicates over a robust current loop rather than a ground-referenced voltage.
Key features include selectable 4-20mA or 0-20mA output ranges, precalibrated input ranges, a precision 10.000V reference, and single- or dual-supply operation. The wide power-supply range extends to +36V, allowing the transmitter to operate from industrial supply systems. Its input buffer accepts either directly scaled process signals or a current-mode DAC output, reducing the need for additional conditioning circuitry in transmitter front ends.
The AD694AR uses an internal reference and input amplifier to establish the relationship between input voltage and loop current. An open-loop alarm function provides an additional indication for systems that need to distinguish a live transmitter from a broken cable, disconnected field device, or other interruption in the current-loop path. These functions make the device suitable for process-control loops in which output accuracy, fault indication, and supply tolerance influence maintenance decisions.
Typical applications include pressure and temperature process transmitters, valve-position controllers, current-loop sensor interfaces, industrial actuator drivers, laboratory control equipment, and programmable test systems. The device is particularly relevant when an upstream ADC, DAC, or control signal must be translated into a standard 4-20mA field output.
Layout and power design should preserve the accuracy and noise performance of the current-loop output. Keep the loop-current return path compact, place the supply-decoupling capacitor close to the device, observe the indicated pin polarity, and account for output compliance when selecting the field-device load. The loop voltage available to the load depends on supply voltage, transmitter output requirements, and the resistance of the field wiring.
This page consolidates the device function, package information, drop-in alternatives, process-control applications, and practical implementation guidance. It also distinguishes direct replacements from merely similar current-transmitter products so engineers can focus on package, pin compatibility, supply range, and loop behavior before changing a design.
بدائل مباشرة لـ AD694AR — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع AD694AR (نفس عامل الشكل والبصمة) — يختلف في Mounting Type, Package.
AD694ARZ
✅ بديل مباشرتواصل لمعرفة السعر
عرض ورقة البيانات ←AD694BRZ
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
AD694AR المواصفات
| Product Type | Monolithic current transmitter IC |
| Nominal Loop Output | 4-20 mA |
| Alternate Output Range | 0-20 mA |
| Input Signal Type | High-level voltage input |
| Precision Reference | 10.000 V |
| Maximum Supply Voltage | +36 V |
| Supply Operation | Single or dual supply |
| Input Buffer Amplifier | 1 amplifier |
| Alarm Function | Open-loop alarm |
| Output Compliance | Wide output compliance |
| العلبة | 16-pin SOIC |
| نوع التركيب | Surface mount |
| عدد الأطراف | 16 pins |
| Application | Process control |
دليل تكوين أطراف AD694AR 16-pin soic
تكوين الأطراف لـ AD694AR (حزمة 16-pin soic). يتم تعريف ترقيم الأطراف والوظائف ومخططات التوصيل في ورقة البيانات الفنية من الشركة المصنعة. راجعها للحصول على البصمة الدقيقة وإرشادات اللحام.
لا تتوفر بيانات مفصلة لمخطط التوصيلات لـ AD694AR.
راجع ورقة البيانات للحصول على تكوين الأطراف الكامل.
التطبيقات النموذجية
AD694AR مناسب لـ 6 التطبيقs: Industrial Pressure Transmitter Interface, Temperature Process-Control Loops, Valve and Actuator Control, Current-Mode DAC Control Interface, Laboratory Instrumentation Control, Remote Sensor Current-Loop Interface.
Industrial Pressure Transmitter Interface
The AD694AR fits industrial pressure-transmitter interfaces that require a voltage command to become a standard field-loop current. According to the Analog Devices AD694 manufacturer datasheet, the input buffer can scale a high-level voltage or buffer a current-mode DAC output, while the transmitter supports 4-20mA and 0-20mA ranges. Placing the AD694AR between a control signal and a remote pressure sensor lets the loop carry a proportional current over field wiring. The open-loop alarm function can also help the host system identify a disconnected field device, although the final alarm behavior must be verified against the loop architecture and application circuitry.
موصى به
Temperature Process-Control Loops
The AD694AR is appropriate for temperature process-control systems in which a controller must command a remote valve or actuator through a 4-20mA loop. Its precision 10.000V reference, input amplifier, and selectable loop ranges provide an integrated signal-conditioning path instead of requiring separate buffer and current-source stages. The device operates from a single or dual supply and supports power-supply levels up to +36V, which is useful for industrial equipment with a 24V-style input after regulation. Designers should still calculate the loop voltage available across the field device and wiring resistance before selecting the supply and protection components.
موصى به
Valve and Actuator Control
The AD694AR can translate a high-level command into the 4-20mA current commonly used to control pneumatic valves and actuators in process systems. The Analog Devices AD694 manufacturer datasheet identifies this use case directly and notes that the buffered input can scale the source signal for the transmitter. This integration reduces the number of discrete conditioning blocks in a compact control module while retaining a standardized field interface. The output-compliance requirement and the load presented by the actuator must both be checked, especially when long cables, input filters, or multiple field devices increase the voltage burden across the loop.
موصى به
Current-Mode DAC Control Interface
The AD694AR is suitable when a current-mode DAC must drive a conventional industrial current loop. Its input amplifier can buffer the DAC output, and the internal current transmitter converts the conditioned signal into a selectable 4-20mA or 0-20mA output. This arrangement is useful in programmable process-control and automated test equipment because it preserves a familiar analog field interface while the command originates from a digital system. Keep the DAC-to-input path short, observe the manufacturer-recommended input network, and confirm that the transmitter's input range matches the DAC's output level rather than relying on an approximate signal level.
موصى به
Laboratory Instrumentation Control
The AD694AR can provide a standardized current output for laboratory instruments that need to emulate industrial field transmitters. Its input buffer accepts a scalable high-level signal, and the selectable 4-20mA or 0-20mA modes support common process-control test setups. The integrated open-loop alarm gives a test system an additional way to identify a disconnected load or interrupted return path. For bench applications, verify the maximum output compliance against the selected precision load, account for cable resistance, and use shielded routing where the loop operates beside low-level analog measurement circuitry.
موصى به
Remote Sensor Current-Loop Interface
The AD694AR supports remote sensor interfaces that transmit a proportional command through a current loop. The Analog Devices AD694 manufacturer datasheet describes the device as a monolithic transmitter for valves, actuators, and process-control equipment, with wide output compliance and a supply range extending to +36V. These characteristics make it useful in distributed systems where long field wiring and varying burdens must be accommodated. The design should include loop protection appropriate to the installation, verify the grounding method for the selected transmitter topology, and confirm that the available supply voltage remains above the burden voltage plus the AD694AR output-compliance margin.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ AD694AR — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | AD694ARZ | AD694BRZ |
|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices |
| Package | 16-pin SOIC | 16-pin SOIC - same | 16-pin SOIC - same |
| Product Type | Monolithic current transmitter IC | 4-20mA current transmitter | 4-20mA current transmitter |
| Nominal Output Range | 4-20 mA | 4-20 mA | 4-20 mA |
| Alternate Output Range | 0-20 mA | 0-20 mA | 0-20 mA |
| Precision Reference | 10.000 V | 10.000 V | 10.000 V |
| Maximum Supply Voltage | +36 V | +36 V | +36 V |
| Input Buffer | Input amplifier with scaling or current-mode DAC buffering capability | Input amplifier | Input amplifier |
| Alarm Function | Open-loop alarm | Open-loop alarm | Open-loop alarm |
أبرز الفروقات
- Lead-free sourcing option with the same electrical footprint (مقابلAD694AR)
- Complete same-footprint replacement without PCB modification (مقابلAD694ARZ)
- Integrated process-transmitter functions reduce external conditioning (مقابلAD694BRZ)
ملاحظات التصميم
Treat output compliance as a system constraint rather than an isolated device rating. Calculated: the loop burden is Vburden = Iloop x Rtotal, where Rtotal includes the field device, cabling, and any input resistance in the current path. Use the maximum required loop current and total resistance to verify that the supply voltage provides enough headroom for the AD694AR output stage. Do not select a replacement solely from its 4-20mA label because identical current ranges do not guarantee identical compliance behavior.
Place the supply-decoupling capacitor and any recommended input or output network close to their associated AD694AR pins. Keep the supply and return traces short, preserve a continuous ground reference beneath the SOIC footprint where practical, and avoid routing the sensitive input path alongside the loop-current output. Follow the package drawing and pin-description table in the Analog Devices AD694 manufacturer datasheet because incorrect numbering can connect the loop or alarm terminals incorrectly.
Single- or dual-supply operation must be selected deliberately for the field-bus architecture and grounding method. Before power-up, verify that the selected supply stays within the +36V limit, that the circuit can satisfy the output-compliance requirement, and that no field wiring imposes a surge beyond the operating ratings. Add only the protection and filtering recommended by the manufacturer application circuit so that loop stability and current accuracy are not degraded.
The input amplifier can scale a high-level signal or buffer a current-mode DAC output, but both uses require correct gain and input-range configuration. Keep the source impedance and input-network values within the manufacturer guidance, and place the input return close to the device's reference connection. In laboratory systems, isolate sensitive measurement channels from the 4-20mA output route to prevent coupling from long field wiring into low-level analog signals.
معلومات الامتثال
The AD694ARZ replacement listing identifies the AD694ARZ ordering variant as RoHS-compliant and lead-free. Explicit status for AD694AR, REACH, AEC-Q100, halogen-free, and conflict-minerals requirements is not available.