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Analog Devices Inc. AD8642ARZ
- Part No.:
- AD8642ARZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD8642ARZ.pdf
- Description:
- IC OPAMP JFET 2 CIRCUIT 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:521
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Product details
Overview
AD8642ARZ from Analog Devices is a dual-channel, rail-to-rail output, precision JFET-input operational amplifier optimized for low-power, high-impedance signal conditioning. It delivers 750 µV max offset voltage, 1 pA max input bias current, and 250 µA max supply current per amplifier across −40°C to +125°C, enabling use in photodiode amplifiers and battery-powered medical instrumentation.
For engineers reviewing the AD8642ARZ datasheet, AD8642ARZ pinout, AD8642ARZ application, or AD8642ARZ equivalent, key selection criteria include its dual SOIC-8 package, ±2.5 V to ±13 V / 5 V to 26 V supply flexibility, unity-gain stability with >500 pF capacitive load drive, and guaranteed rail-to-rail output swing without phase reversal.
Technical Context
The AD8642ARZ implements a JFET-input stage to achieve femtoampere-level input bias current and high input impedance (>1012 Ω), critical for precision current sensing and photodiode transimpedance applications. Its fully differential input stage supports common-mode voltages from VS− to (VS+ − 3 V) in single-supply mode and −13 V to +10 V in dual-supply mode.
Internally compensated for unity-gain stability, the device maintains ≥50° phase margin with 2 kΩ load and 40 pF capacitance, and sustains stable operation driving capacitive loads up to 500 pF-enabling direct interface with ADC reference buffers and DAC output stages without external isolation resistors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Current/Amplifier | 250 µA max - enables dual-channel operation at <500 µA total, suitable for multichannel portable instruments. |
| Input Bias Current | 1 pA max - preserves signal integrity in high-Z sensor interfaces like photodiodes and pH electrodes. |
| Offset Voltage | 750 µV max - ensures ≤0.015% gain error in 5 V full-scale precision current-sensing shunt amplifiers. |
| Rail-to-Rail Output | VOH = 4.95 V, VOL = 0.05 V @ 5 V supply - delivers full dynamic range into 10 kΩ load, maximizing SNR in single-supply data acquisition. |
| Gain Bandwidth Product | 3 MHz - supports stable closed-loop operation up to 100 kHz at G = +10, sufficient for anti-aliasing and active filter stages. |
| Operating Temperature | −40°C to +125°C - qualified for under-hood automotive sensors and industrial control loop amplifiers. |
| Input Voltage Range | 0 V to 3 V @ 5 V supply - allows direct buffering of CMOS DAC outputs without level-shifting circuitry. |
Pinout & Package
AD8642ARZ is housed in an 8-lead SOIC_N (R-8) package, 4.90 mm × 3.90 mm × 1.75 mm body, RoHS-compliant, with standard JEDEC MS-012-AA footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: OUT A | Amplifier A output | Delivers rail-to-rail buffered signal; drives 10 kΩ load to within 50 mV of rails at 1 mA. |
| 2: –IN A | Inverting input A | High-impedance JFET node; bias current ≤1 pA enables >100 MΩ feedback networks. |
| 3: +IN A | Non-inverting input A | Accepts common-mode voltage from VS− to (VS+ − 3 V); supports single-supply sensor interfacing. |
| 4: V– | Negative supply | Connect to ground (single-supply) or negative rail (dual-supply); must be decoupled with 0.1 µF ceramic. |
| 5: +IN B | Non-inverting input B | Independent channel input; identical specs to Channel A for matched dual-channel performance. |
| 6: –IN B | Inverting input B | Electrically isolated from Channel A; enables independent gain/offset configuration per channel. |
| 7: OUT B | Amplifier B output | Unity-gain stable; no phase reversal observed even with inputs driven beyond supply rails. |
| 8: V+ | Positive supply | Accepts 5 V to 26 V (single) or ±2.5 V to ±13 V (dual); PSRR ≥90 dB minimizes supply noise coupling. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low input bias current | 1 pA max ensures <1 µV error in 1 GΩ feedback resistor at 25°C, critical for electrometer-grade circuits. |
| No phase reversal | Guaranteed over full common-mode range prevents latch-up or signal inversion when inputs exceed rails-essential for fault-tolerant sensor front-ends. |
| Rail-to-rail output swing | Drives to within 50 mV of either rail at 1 mA load, preserving >98% of 5 V full-scale range for high-resolution ADC interfacing. |
| Capacitive load drive | Stable with >500 pF load enables direct connection to long PCB traces, LCD bias lines, or sampling capacitors without isolation resistors. |
| Extended temperature range | Specified from −40°C to +125°C with monotonic drift behavior, supporting automotive cabin and industrial motor-control environments. |
Applications
| Photodiode Amplifier | Precision Current Sensing |
|---|---|
Use Scenario: Converting nanoamp-level photocurrent from a reverse-biased silicon photodiode into a measurable voltage signal. IC Role / Device Role / Timing Role: Transimpedance amplifier with ultra-low input bias current and high open-loop gain to minimize shot-noise contribution. Use Value: 1 pA input bias current avoids signal corruption in 100 MΩ–1 GΩ feedback configurations, enabling sub-nA detection resolution. | Use Scenario: Amplifying mV-level voltage drop across a precision shunt resistor in a battery management system. IC Role / Device Role / Timing Role: High-common-mode rejection difference amplifier front-end with rail-to-rail output for 0–5 V ADC input scaling. Use Value: 750 µV max offset voltage limits current measurement error to <0.015% of full scale at 5 V output range. |
| Medical Instrumentation | Industrial Controls |
Use Scenario: Buffering low-output-impedance signals from ECG electrode amplifiers before analog filtering and digitization. IC Role / Device Role / Timing Role: Unity-gain buffer with high input impedance and low noise to prevent loading of high-Z biopotential sources. Use Value: 28.5 nV/√Hz voltage noise density at 1 kHz and 4.0 µV p-p 0.1–10 Hz noise preserve microvolt-level cardiac waveform fidelity. | Use Scenario: Conditioning analog sensor outputs (e.g., RTD, strain gauge) in programmable logic controller (PLC) analog input modules. IC Role / Device Role / Timing Role: Precision gain stage with wide supply range (±2.5 V to ±13 V) to accommodate legacy industrial power rails. Use Value: Dual-supply operation down to ±2.5 V allows compatibility with 5 V logic systems while maintaining 12 mA output drive capability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar precision op-amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA211AIDR | Lower 1.1 nV/√Hz voltage noise, but 3.5 nA input bias current - 3.5× higher than AD8642ARZ's 1 pA. | Better for low-noise voltage amplification; unsuitable for high-Z current sensing where bias current dominates error. | Select OPA211AIDR when voltage noise is primary concern and source impedance <100 kΩ; retain AD8642ARZ for photodiode or pH electrode interfaces. |
| ADA4625-2ARZ | Higher 5.8 MHz GBW and 12 V/µs slew rate, but 2.5 pA input bias current and 1.25 mV max offset voltage. | Preferred for higher-speed precision filtering; less accurate for DC-critical applications requiring sub-mV offset. | Choose ADA4625-2ARZ for active filters above 100 kHz; choose AD8642ARZ for DC-stable, low-drift sensor conditioning below 10 kHz. |
Compared with OPA211AIDR and ADA4625-2ARZ, AD8642ARZ uniquely balances femtoampere input bias, millivolt-level offset, and rail-to-rail output in a cost-effective SOIC-8 package-making it optimal for battery-powered, high-impedance, low-frequency precision signal chains where bias current and DC accuracy dominate performance trade-offs.
Availability
AD8642ARZ is available at Aetrix Electronics and suitable for photodiode amplifiers, precision current sensing, and medical instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AD8642ARZ 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 AD864x family was designed specifically for low-power, high-precision signal conditioning in space-constrained, thermally sensitive applications-including portable diagnostics, battery monitoring, and industrial sensor nodes-where JFET input performance and rail-to-rail output are essential.
FAQ
What is the maximum capacitive load the AD8642ARZ can drive while remaining stable?
The AD8642ARZ is specified to remain stable with capacitive loads exceeding 500 pF when configured as a unity-gain buffer. This capability eliminates the need for external isolation resistors in applications such as driving ADC input capacitors, LCD bias lines, or long PCB traces-reducing component count and preserving signal integrity without compromising phase margin.
Does the AD8642ARZ exhibit phase reversal when input voltages exceed the supply rails?
No, the AD8642ARZ guarantees no phase reversal across its full common-mode input range, including conditions where inputs exceed the positive or negative supply rails. This behavior is explicitly verified in the datasheet (Figure 34) and makes AD8642ARZ suitable for fault-tolerant front-ends in industrial and medical systems where transient overvoltage events may occur.
What is the typical input offset voltage drift of the AD8642ARZ over temperature?
The AD8642ARZ has a guaranteed offset voltage drift of 2.5 µV/°C over the full −40°C to +125°C operating range. This low drift ensures minimal calibration drift in precision current-sensing or sensor-conditioning applications, contributing to long-term accuracy without frequent recalibration in field-deployed equipment.
Can the AD8642ARZ operate from a single 5 V supply while delivering rail-to-rail output?
Yes, the AD8642ARZ supports single-supply operation from 5 V to 26 V and delivers true rail-to-rail output swing-achieving VOH = 4.95 V and VOL = 0.05 V at 1 mA load with a 5 V supply. This enables full utilization of 5 V ADC input ranges and simplifies power architecture in portable and line-powered instrumentation.
Is the AD8642ARZ pin-compatible with other dual op-amps in SOIC-8 packages?
The AD8642ARZ follows the industry-standard SOIC-8 pinout for dual op-amps (pin 1 = OUT A, pin 2 = –IN A, pin 3 = +IN A, pin 4 = V–, pin 5 = +IN B, pin 6 = –IN B, pin 7 = OUT B, pin 8 = V+), matching common footprints like the OP27, AD8602, and LM7322. However, electrical characteristics-including input bias current, offset voltage, and supply current-are unique to the AD8642ARZ and require validation in target circuits.
AD8642ARZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- J-FET
- Number of Circuits:
- 2
- Output Type:
- Rail-to-Rail
- Slew Rate:
- 3V/µs
- Gain Bandwidth Product:
- 3.5 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 0.25 pA
- Voltage - Input Offset:
- 70 µV
- Current - Supply:
- 200µA (x2 Channels)
- Current - Output / Channel:
- 12 mA
- Voltage - Supply Span (Min):
- 5 V
- Voltage - Supply Span (Max):
- 26 V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
AD8642ARZ FAQ
1.How can I place an order for AD8642ARZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD8642ARZ 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 AD8642ARZ reliable?
The price and inventory of AD8642ARZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD8642ARZ is usually 5 days.
3.What payment methods are accepted for AD8642ARZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD8642ARZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD8642ARZ?
AD8642ARZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD8642ARZ 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 AD8642ARZ?
For technical support, including AD8642ARZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD8642ARZ requirements.
6.How does Aetrix verify that AD8642ARZ is sourced from the original manufacturer or authorized distributors?
All AD8642ARZ 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 AD8642ARZ meets industry standards.
7.What is the process for return or replacement of AD8642ARZ?
All AD8642ARZ units undergo pre-shipment inspection (PSI). If there is an issue with AD8642ARZ, 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 AD8642ARZ part is unused and in its original packaging.
Return procedure for AD8642ARZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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