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Analog Devices Inc. AD8684ARZ
- Part No.:
- AD8684ARZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD8684ARZ.pdf
- Description:
- IC OPAMP JFET 4 CIRCUIT 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:116
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Product details
Overview
AD8684ARZ from Analog Devices is a quad, low-power, precision JFET-input operational amplifier optimized for high-speed performance at ultra-low supply current (250 μA/amp max). It delivers 9 V/μs slew rate, 3.5 MHz gain bandwidth, and 1 mV max input offset voltage at 25°C, enabling high-accuracy signal conditioning in portable medical instrumentation and loop filter applications.
For engineers reviewing the AD8684ARZ datasheet, AD8684ARZ pinout, AD8684ARZ application, or AD8684ARZ equivalent, key selection criteria include its rail-to-rail input common-mode range (−11 V to +15 V), 20 pA max input bias current at 25°C, unity-gain stability, and compatibility with high-impedance sensor interfaces requiring low power and dc precision.
Technical Context
The AD8684ARZ employs a JFET input stage to achieve sub-picoamp bias current and high input impedance, supporting precision amplification of signals from high-source-impedance sensors. Its unity-gain stable architecture and 55° phase margin ensure robust closed-loop operation across load capacitances up to 500 pF without external compensation.
It operates over ±4.5 V to ±18 V supplies and −40°C to +85°C, with CMRR of 90 dB typical and PSRR of 114 dB typical - critical for rejecting supply noise in battery-powered instrumentation. The device maintains 7 V/μs min slew rate and 1.6 μs settling time to 0.01%, enabling fast transient response in active filters and integrators.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Current per Amplifier | 250 μA max - enables multi-channel battery operation for >1000-hour runtime in portable medical devices. |
| Slew Rate | 9 V/μs typical - supports clean amplification of fast transients in strain gauge and supply current monitoring circuits. |
| Gain Bandwidth Product | 3.5 MHz - allows stable unity-gain configuration while maintaining sufficient bandwidth for 125 kHz full-power signals. |
| Input Offset Voltage | 1 mV max at 25°C - ensures ≤0.1% gain error in 10× precision gain stages without trimming. |
| Input Bias Current | 20 pA max at 25°C - minimizes voltage error across 10 MΩ source impedances (≤0.2 mV error). |
| Common-Mode Rejection Ratio | 90 dB typical - rejects >30 kΩ imbalance-induced errors in differential sensing topologies. |
| Operating Temperature Range | −40°C to +85°C - qualified for industrial and portable telecom equipment deployed in uncontrolled environments. |
Pinout & Package
AD8684ARZ is housed in a 14-lead SOIC_N (R-14) package, 8.75 mm × 4.00 mm × 1.75 mm, RoHS-compliant, with standard JEDEC MS-012-AB footprint and 1.27 mm lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | OUT A | Amplifier A output - drives loads ≥10 kΩ directly; capable of ±13.9 V swing with ±15 V supplies. |
| 2 | –IN A | Inverting input of Amp A - high-impedance JFET node; requires guarding in high-Z PCB layouts. |
| 3 | +IN A | Non-inverting input of Amp A - accepts common-mode voltages from −11 V to +15 V, enabling high-side sensing. |
| 4 | V+ | Positive supply rail - must be decoupled with ≥0.1 μF ceramic capacitor near pin for stability. |
| 5 | +IN B | Non-inverting input of Amp B - electrically identical to Pin 3; shares same input stage characteristics. |
| 6 | –IN B | Inverting input of Amp B - matched to Pin 2; supports dual-channel differential configurations. |
| 7 | OUT B | Amplifier B output - independent channel; no crosstalk specified beyond typical 100 dB at DC. |
| 8 | OUT C | Amplifier C output - third channel; enables 3-op-amp instrumentation amp or triple-filter topologies. |
| 9 | –IN C | Inverting input of Amp C - fully isolated; layout symmetry recommended for matching with Pins 2 & 6. |
| 10 | +IN C | Non-inverting input of Amp C - supports rail-to-rail common-mode operation like Pins 3 & 5. |
| 11 | V– | Negative supply rail - reference for all four amplifiers; requires low-impedance return path. |
| 12 | +IN D | Non-inverting input of Amp D - fourth channel input; enables quad integrator or state-variable filter designs. |
| 13 | –IN D | Inverting input of Amp D - matched performance to other inputs; validated for phase-inversion immunity to −11 V. |
| 14 | OUT D | Amplifier D output - completes quad functionality; supports independent feedback networks per channel. |
Key Features
| Feature | Design Value |
|---|---|
| Low input bias current (20 pA max) | Enables accurate amplification of signals from piezoelectric sensors, pH electrodes, and photodiode transimpedance stages without leakage-induced drift. |
| Rail-to-rail input common-mode range (−11 V to +15 V) | Supports direct high-side current sensing across shunt resistors tied to positive supply, eliminating level-shifting circuitry. |
| Unity-gain stable with 55° phase margin | Permits use in G = 1 noninverting buffers and active filters without external compensation components or stability risk. |
| 3.5 MHz gain bandwidth at 250 μA supply current | Delivers bandwidth comparable to higher-power op amps while consuming <1/3 the quiescent power of legacy JFET parts. |
| Low 1 mV max offset voltage at 25°C | Reduces need for system-level calibration in portable medical front-ends such as ECG and pulse oximetry analog signal chains. |
Applications
| Portable Medical Instrumentation | High-Side Supply Current Monitoring |
|---|---|
|
Use Scenario: Amplifying low-amplitude bio-signals (e.g., ECG leads, EEG electrodes) in handheld diagnostic devices powered by coin-cell or Li-ion batteries. IC Role / Device Role / Timing Role: Precision dc-coupled signal conditioning amplifier with ultra-low input bias current and offset drift to preserve microvolt-level signal integrity. Use Value: Enables >100 dB SNR in 1 kHz bandwidth with <250 μA per channel supply draw, extending battery life without sacrificing diagnostic accuracy. |
Use Scenario: Measuring load current in telecom power modules by amplifying voltage drop across a 0.1 Ω sense resistor connected between +15 V rail and load. IC Role / Device Role / Timing Role: High-common-mode-input difference amplifier configured as a noninverting buffer for high-side shunt sensing. Use Value: Achieves ±0.5% current measurement accuracy over temperature using only passive components, with no level-shifter IC required. |
| Active Precision Filters | Strain Gauge Signal Conditioning |
|
Use Scenario: Implementing 2nd-order Butterworth low-pass filters in navigation-grade IMU signal paths where phase linearity and group delay stability are critical. IC Role / Device Role / Timing Role: Quad op amp configured as dual biquad sections (LPF + HPF) in state-variable topology with programmable Q and cutoff frequency. Use Value: Maintains <0.1° phase error across 10 Hz–1 kHz band while drawing <1 mA total, enabling real-time vibration analysis on edge nodes. |
Use Scenario: Amplifying Wheatstone bridge outputs from metal foil strain gauges in industrial load cells with excitation voltages up to ±15 V. IC Role / Device Role / Timing Role: Instrumentation-grade amplifier front-end with matched input bias current minimizing thermal EMF errors in 4-wire bridge configurations. Use Value: Delivers <50 ppm nonlinearity over 0–100 mV input range with <1 μV/°C offset drift, meeting Class C load cell metrology requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad JFET op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OP484ESZ | Higher supply current (650 μA/amp), wider GBW (4.25 MHz), but larger offset (1.5 mV max) and lower CMRR (80 dB). | Better for high-speed active filters needing >3.5 MHz bandwidth; less suitable for ultra-low-power portable designs. | Select OP484ESZ when speed outweighs battery life; AD8684ARZ preferred for <250 μA/channel constraints. |
| TL084CDR | JFET input, but higher IB (30 pA typ), higher VOS (6 mV max), and no guaranteed −40°C operation; not unity-gain stable. | Acceptable for cost-sensitive industrial controls with relaxed precision and temperature requirements. | Choose TL084CDR only for non-critical, room-temperature applications; AD8684ARZ provides verified performance across full industrial range. |
Compared with OP484ESZ and TL084CDR, AD8684ARZ uniquely balances ultra-low quiescent current, rail-to-rail input capability, and guaranteed unity-gain stability - making it the only option qualified for battery-powered precision instrumentation demanding both dc accuracy and dynamic response.
Availability
AD8684ARZ is available at Aetrix Electronics and suitable for portable medical instrumentation, high-side current monitoring, and active precision filter designs requiring stable component supply with full industrial temperature qualification.
Supply support for AD8684ARZ 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, headquartered in Norwood, MA.
The AD868x family was designed specifically for low-power, high-precision signal conditioning in portable and battery-operated systems - emphasizing JFET input performance, micropower efficiency, and robustness in high-impedance sensor interfaces.
FAQ
What is the maximum operating supply voltage for AD8684ARZ?
The AD8684ARZ supports a supply voltage range of ±4.5 V to ±18 V, with absolute maximum ratings of ±18 V on both V+ and V− pins. Operation beyond ±18 V risks permanent damage, and input voltages must remain within the supply rails unless explicitly rated for overvoltage tolerance - which AD8684ARZ does not specify.
Does AD8684ARZ support rail-to-rail output swing?
No, AD8684ARZ does not provide rail-to-rail output swing. With ±15 V supplies, its typical output voltage swing is ±13.9 V (i.e., within 1.1 V of each rail). Output swing degrades with increasing load current and temperature, and minimum guaranteed swing is ±13.5 V under RL = 10 kΩ conditions per the datasheet.
Can AD8684ARZ drive capacitive loads without oscillation?
Yes, AD8684ARZ is unity-gain stable and characterized for driving capacitive loads up to 500 pF with minimal overshoot (<10%) when RL = 2 kΩ. For loads >100 pF, layout best practices (short traces, local decoupling, ground plane) are essential; no external isolation resistor is required for stability in G = 1 configurations.
Is AD8684ARZ pin-compatible with other quad op amps like LM324 or TL084?
No, AD8684ARZ is not pin-compatible with LM324 or TL084. It uses a 14-lead SOIC_N (R-14) pinout distinct from the 14-lead SOIC of TL084 (which has different pin assignments for V+, V−, and outputs) and incompatible with LM324's 14-lead DIP/SOIC layout. Direct replacement requires PCB redesign.
What is the input common-mode voltage range of AD8684ARZ?
The AD8684ARZ guarantees an input common-mode voltage range of −11 V to +15 V with ±15 V supplies - meaning it can accurately amplify signals referenced to the positive rail (e.g., high-side current sensing), unlike many op amps limited to V+ − 1.5 V. This range scales linearly with supply voltage per datasheet specifications.
AD8684ARZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- J-FET
- Number of Circuits:
- 4
- Output Type:
- -
- Slew Rate:
- 9V/µs
- Gain Bandwidth Product:
- 3.5 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 6 pA
- Voltage - Input Offset:
- 350 µV
- Current - Supply:
- 210µA (x4 Channels)
- Current - Output / Channel:
- 12 mA
- Voltage - Supply Span (Min):
- 9 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
AD8684ARZ FAQ
1.How can I place an order for AD8684ARZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD8684ARZ 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 AD8684ARZ reliable?
The price and inventory of AD8684ARZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD8684ARZ is usually 5 days.
3.What payment methods are accepted for AD8684ARZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD8684ARZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD8684ARZ?
AD8684ARZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD8684ARZ 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 AD8684ARZ?
For technical support, including AD8684ARZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD8684ARZ requirements.
6.How does Aetrix verify that AD8684ARZ is sourced from the original manufacturer or authorized distributors?
All AD8684ARZ 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 AD8684ARZ meets industry standards.
7.What is the process for return or replacement of AD8684ARZ?
All AD8684ARZ units undergo pre-shipment inspection (PSI). If there is an issue with AD8684ARZ, 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 AD8684ARZ part is unused and in its original packaging.
Return procedure for AD8684ARZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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