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Analog Devices Inc. AD745JN
- Part No.:
- AD745JN
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
AD745JN.pdf
- Description:
- IC OPAMP JFET 1 CIRCUIT 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,922
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Product details
Overview
AD745JN from Analog Devices (manufactured under license by Rochester Electronics) is an ultralow-noise, high-speed BiFET operational amplifier with FET-input architecture, 20 MHz gain-bandwidth product, 12.5 V/µs slew rate, and no output phase reversal - used in precision instrumentation front-ends and high-fidelity signal conditioning paths.
For engineers reviewing the AD745JN datasheet, AD745JN pinout, AD745JN application, or AD745JN equivalent, key selection criteria include input voltage noise density (2.9 nV/√Hz), input bias current (25 pA max), dc precision (0.5 mV max input offset voltage), and stability in unity-gain configurations without external compensation.
Technical Context
The AD745JN employs a hybrid bipolar-FET input stage to simultaneously achieve low input current (25 pA max at ±15 V) and low voltage noise (2.9 nV/√Hz at 1 kHz), enabling high-resolution measurement in sensor interfaces where both speed and dc accuracy are critical. Its internal compensation ensures stable operation at unity gain without external components.
It features rail-to-rail output swing within 1.5 V of supply rails (±15 V), operates over ±4.5 V to ±18 V supplies, and maintains monotonic phase response up to 20 MHz - eliminating output polarity inversion during input overdrive, a known failure mode in older FET op amps.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Gain-Bandwidth Product | 20 MHz - supports closed-loop bandwidth up to 20 MHz at unity gain, suitable for fast pulse amplification and active filter design. |
| Slew Rate | 12.5 V/µs - enables faithful reproduction of signals with rise times down to ~250 ns without distortion. |
| Input Voltage Noise | 2.9 nV/√Hz @ 1 kHz - preserves SNR in low-level transducer signal chains (e.g., strain gauge, piezoelectric sensors). |
| Input Bias Current | 25 pA max @ ±15 V - minimizes voltage error across high-impedance sources (e.g., photodiode, pH electrode). |
| Input Offset Voltage | 0.5 mV max - ensures ≤0.003% full-scale error in 16-bit data acquisition systems with ±10 V input range. |
| Supply Voltage Range | ±4.5 V to ±18 V - compatible with standard industrial dual-rail supplies and allows headroom for ±12 V or ±15 V operation. |
Pinout & Package
AD745JN is supplied in an 8-pin PDIP (Plastic Dual In-line Package) with 0.3-inch body width and standard through-hole footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Offset Null | Connects to external potentiometer for fine-tuning input offset voltage; unused in most applications. |
| 2 | Inverting Input (–) | High-impedance FET input node; requires guarded layout to preserve 25 pA bias current spec. |
| 3 | Noninverting Input (+) | High-impedance FET input node; matched to Pin 2 for common-mode rejection. |
| 4 | V– | Negative supply terminal; must be decoupled with ≥0.1 µF ceramic capacitor near package. |
| 5 | Offset Null | Second terminal of offset null network; tied to wiper of 10 kΩ potentiometer with ends at Pins 1 and 5. |
| 6 | Output | Capacitive-load tolerant output capable of driving ≥500 pF without oscillation. |
| 7 | V+ | Positive supply terminal; requires local 0.1 µF ceramic decoupling for high-frequency stability. |
| 8 | NC | No connect - internally unconnected; must remain floating per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| No output phase reversal | Eliminates catastrophic polarity inversion during input overdrive - critical for closed-loop control and safety-critical monitoring circuits. |
| Internal unity-gain compensation | Enables stable operation without external compensation components, reducing BOM count and PCB area in gain-of-one buffers. |
| Rail-to-rail output swing | Delivers >27 Vpp output into 2 kΩ load with ±15 V supplies - maximizes dynamic range in analog-to-digital interface stages. |
| Low input capacitance (3 pF) | Minimizes peaking and phase shift in high-Z sensor interfaces, preserving frequency response up to 20 MHz. |
Applications
| Medical Instrumentation | Test & Measurement Equipment |
|---|---|
Use Scenario: Amplifying low-amplitude bioelectric signals (e.g., ECG, EEG) with minimal added noise and no DC drift. IC Role / Device Role / Timing Role: First-stage instrumentation amplifier with FET input guarding and 20 MHz bandwidth for artifact rejection. Use Value: 2.9 nV/√Hz input noise preserves microvolt-level signal integrity; 25 pA bias current prevents electrode polarization errors. | Use Scenario: Buffering and conditioning signals in automated test equipment (ATE) channel modules. IC Role / Device Role / Timing Role: High-fidelity unity-gain buffer between DAC output and DUT interface, maintaining signal fidelity up to 5 MHz. Use Value: 12.5 V/µs slew rate ensures <1% settling error for 10 V step inputs within 800 ns; no phase reversal avoids false fault triggers. |
| Industrial Sensor Signal Conditioning | High-Resolution Data Acquisition |
Use Scenario: Conditioning outputs from high-impedance sensors (e.g., piezoresistive pressure transducers, RTDs with 3-wire bridges). IC Role / Device Role / Timing Role: Low-drift, low-noise gain stage preceding sigma-delta ADC, operating from ±15 V rails. Use Value: 0.5 mV max input offset contributes <0.005% error in 10 V full-scale systems; 20 MHz GBW supports anti-alias filtering at 100 kHz. | Use Scenario: Front-end amplifier in 16-bit+ data loggers requiring dc precision and wideband noise performance. IC Role / Device Role / Timing Role: Precision gain block with selectable gain (1–100) using external resistors, optimized for low THD+N. Use Value: 2.9 nV/√Hz noise floor enables effective resolution >16 bits at 1 kHz; rail-to-rail output drives ADC reference buffers directly. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed, low-noise op amp applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| OPA134PA | Lower noise (1.1 nV/√Hz), lower GBW (8 MHz), higher input bias current (100 pA) | Better for audio-grade low-noise but unsuitable for >5 MHz signal paths | Select OPA134PA only when bandwidth <8 MHz suffices and ultra-low noise dominates over speed. |
| LT1357CN8#PBF | Higher slew rate (1000 V/µs), higher noise (4.5 nV/√Hz), no phase reversal guarantee | Preferred for pulse amplification >100 ns edges but requires careful layout to manage noise | Choose LT1357CN8#PBF when edge speed is primary; accept 1.6× higher noise for 80× faster slew. |
Compared with OPA134PA and LT1357CN8#PBF, the AD745JN uniquely balances 20 MHz bandwidth, 2.9 nV/√Hz noise, and guaranteed no-phase-reversal behavior - making it the only option among the three qualified for simultaneous high-speed, high-precision, and fail-safe sensor front-ends.
Availability
AD745JN is available at Aetrix Electronics and suitable for medical instrumentation, industrial sensor signal conditioning, high-resolution data acquisition, and test & measurement equipment requiring stable component supply across extended product lifecycles.
Supply support for AD745JN 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 semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.
The AD745JN belongs to Analog Devices' legacy BiFET op amp product line, designed specifically for applications demanding both high dc accuracy and wideband low-noise performance in single-supply or dual-supply configurations.
FAQ
What is the maximum supply voltage rating for the AD745JN?
The AD745JN supports dual supply voltages from ±4.5 V to ±18 V. Operation beyond ±18 V risks permanent damage to the internal FET input stage. At ±15 V, it delivers full rail-to-rail output swing within 1.5 V of each rail and maintains specified noise and offset performance. The AD745JN must not be operated with asymmetric supplies unless explicitly validated in the original Analog Devices datasheet.
Does the AD745JN require external compensation for unity-gain stability?
No, the AD745JN is internally compensated for unity-gain stability and does not require external capacitors or resistors to maintain phase margin. This is confirmed in the original Analog Devices datasheet and verified in Rochester Electronics' requalification testing. The AD745JN remains stable with capacitive loads up to 500 pF, though layout best practices (short traces, local decoupling) are still required to prevent parasitic oscillation.
Is output phase reversal a concern when using the AD745JN in overdriven conditions?
No - the AD745JN is explicitly designed to eliminate output phase reversal during input overdrive, a known limitation of earlier FET-input op amps. This behavior is documented in the original Analog Devices datasheet and confirmed in Rochester Electronics' characterization reports. The AD745JN maintains correct polarity even when inputs exceed common-mode range, making it suitable for fault-tolerant sensor interfaces and closed-loop safety systems.
What is the typical input bias current of the AD745JN at ±15 V supply?
The typical input bias current of the AD745JN is 2 pA at ±15 V, with a maximum specification of 25 pA across temperature and process variation. This ultra-low value enables accurate amplification of signals from high-impedance sources such as photodiodes, piezoelectric sensors, and pH electrodes. The AD745JN's FET input architecture ensures this performance remains stable over time and temperature without significant drift.
Can the AD745JN drive a 600 Ω load effectively?
Yes, the AD745JN can drive a 600 Ω load with ≤0.1% gain error and minimal distortion when configured in unity gain, provided supply voltages are ≥±12 V. Its output stage delivers ±13.5 V swing into 2 kΩ and maintains linearity down to 600 Ω with proper thermal management. For sustained 600 Ω operation, ensure ambient temperature stays below 70°C and use adequate PCB copper pour for heat dissipation. The AD745JN's performance under this load is fully characterized in the original datasheet.
AD745JN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- Amplifier Type:
- J-FET
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 12V/µs
- Gain Bandwidth Product:
- 20 MHz
- -3db Bandwidth:
- 20 MHz
- Current - Input Bias:
- 150 pA
- Voltage - Input Offset:
- 250 µV
- Current - Supply:
- 8mA
- Current - Output / Channel:
- 40 mA
- Voltage - Supply Span (Min):
- 9.6 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
AD745JN FAQ
1.How can I place an order for AD745JN through Aetrix?
Please submit a Request for Quotation (RFQ) for AD745JN 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 AD745JN reliable?
The price and inventory of AD745JN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD745JN is usually 5 days.
3.What payment methods are accepted for AD745JN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD745JN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD745JN?
AD745JN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD745JN 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 AD745JN?
For technical support, including AD745JN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD745JN requirements.
6.How does Aetrix verify that AD745JN is sourced from the original manufacturer or authorized distributors?
All AD745JN 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 AD745JN meets industry standards.
7.What is the process for return or replacement of AD745JN?
All AD745JN units undergo pre-shipment inspection (PSI). If there is an issue with AD745JN, 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 AD745JN part is unused and in its original packaging.
Return procedure for AD745JN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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