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Analog Devices Inc. AD549SH/883B
- Part No.:
- AD549SH/883B
- Manufacturer:
- Analog Devices Inc.
- Category:
- Instrumentation, Op Amps, Buffer Amps
- Package:
- TO-99-8 Metal Can
- Datasheet:
-
AD549SH/883B.pdf
- Description:
- IC OPAMP GP 1 CIRCUIT TO99-8
- Quantity:
- Payment:
- Shipping:
Inventory:2,099
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Product details
Overview
AD549SH/883B from Analog Devices is a military-grade monolithic electrometer operational amplifier featuring ultralow input bias current (75 fA max), low input offset voltage (0.5 mV max), and laser-trimmed offset drift (15 μV/°C max). It operates over −55°C to +125°C and is housed in a hermetic TO-99 metal can package with guard pin (Pin 8) connected to case - optimized for photodiode preamplification, pH electrode buffering, and high-impedance current-to-voltage conversion.
For engineers reviewing the AD549SH/883B datasheet, AD549SH/883B pinout, AD549SH/883B application, or AD549SH/883B equivalent, key selection criteria include guaranteed input bias current over full common-mode range (−10 V to +10 V), MIL-STD-883B processing for reliability, bootstrapped 10¹⁵ Ω common-mode impedance, and compatibility with precision integrator and sample-and-hold topologies requiring sub-picoampere leakage control.
Technical Context
The AD549SH/883B employs Analog Devices' proprietary Topgate™ JFET technology to achieve stable femtoampere-level input bias current across temperature and common-mode voltage. Its bootstrapped input stage delivers 10¹⁵ Ω common-mode impedance, decoupling input current from VCM variations - critical for electrometer-grade signal integrity.
It features laser-trimmed offset voltage and drift, 1 MHz unity-gain bandwidth, 3 V/μs slew rate, and 5 μs settling time to 0.01% for 10 V steps. The TO-99 package integrates a guard pin (Pin 8) tied to the metal case, enabling direct bootstrapping to minimize stray capacitance and leakage paths at the input node.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Bias Current | 75 fA maximum at 25°C, guaranteed over −10 V to +10 V common-mode range - enables accurate measurement of pA-level transducer currents without significant error. |
| Input Offset Voltage | 0.5 mV maximum - ensures minimal dc error in high-gain, low-signal applications like pH sensing and photodiode amplification. |
| Offset Voltage Drift | 15 μV/°C maximum - maintains stability across military temperature range (−55°C to +125°C) without recalibration. |
| Supply Current | 700 μA maximum - minimizes self-heating, preserving low input bias current and offset accuracy under continuous operation. |
| Unity-Gain Bandwidth | 1 MHz - supports fast response in precision analog front-ends while retaining stability with high-impedance sources. |
| Slew Rate | 3 V/μs - enables accurate reproduction of moderate-speed signals in electrometer and sensor interface circuits. |
| Common-Mode Impedance | 10¹⁵ Ω || 0.8 pF - reduces sensitivity to PCB leakage and guarding errors, essential for >100 GΩ source impedances. |
Pinout & Package
AD549SH/883B is supplied in a hermetic TO-99 metal-can package (case connected to Pin 8). The metal case serves as a guard plane when biased near input potential, reducing stray capacitance and surface leakage.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | Offset Null (−) | Connects to one end of external 10 kΩ potentiometer for input offset voltage trimming; introduces ≤1.2 μV/°C added drift when adjusted. |
| 2 | Inverting Input (−) | High-impedance JFET input node; requires guarding and low-leakage PCB layout to preserve <100 fA bias current performance. |
| 3 | Noninverting Input (+) | High-impedance JFET input node; same guarding requirements as Pin 2; differential input voltage must stay within ±1 V to avoid current limiting. |
| 4 | V− (Negative Supply) | Accepts −5 V to −18 V; common return for biasing and output swing reference; must be decoupled with low-ESR capacitor. |
| 5 | Offset Null (+) | Connects to other end of external 10 kΩ potentiometer; used with Pin 1 to null initial offset voltage. |
| 6 | Output | Capable of ±12 V swing into 10 kΩ load; limited to ±10 V into 2 kΩ; stable with up to 4000 pF capacitive load at unity gain. |
| 7 | V+ (Positive Supply) | Accepts +5 V to +18 V; supplies internal circuitry; requires local bypassing to suppress supply noise coupling into high-Z inputs. |
| 8 | Guard / Case | Internally connected to metal case; must be tied to output (for follower) or input guard ring (for inverter) to minimize input node capacitance and leakage. |
Key Features
| Feature | Design Value |
|---|---|
| Ultralow input bias current | 75 fA max (S grade), fully tested and guaranteed over −10 V to +10 V common-mode range - eliminates input current-induced errors in pA-scale measurements. |
| Laser-trimmed offset parameters | 0.5 mV max VOS, 15 μV/°C max drift - ensures long-term dc accuracy without external calibration in harsh environments. |
| Bootstrapped 10¹⁵ Ω common-mode impedance | Enables stable bias current independent of input voltage - critical for high-impedance pH electrodes and ion-selective sensors. |
| MIL-STD-883B Rev. C processing | Includes 168-hour burn-in and environmental screening - qualifies AD549SH/883B for aerospace, defense, and downhole instrumentation where field reliability is non-negotiable. |
| TO-99 guard-pin architecture | Pin 8 directly connects case to guard potential - allows physical shielding of input traces without adding parasitic capacitance or leakage paths. |
Applications
| Photodiode Preamp | pH Electrode Buffer |
|---|---|
Use Scenario: Amplifying nanoampere-level photocurrent from a reverse-biased silicon photodiode in low-light spectroscopy systems. IC Role / Device Role / Timing Role: Electrometer op amp configured as transimpedance amplifier with >1 GΩ feedback resistor and guarded layout. Use Value: 75 fA input bias current prevents signal corruption by input leakage, enabling accurate detection of sub-pW optical power levels. | Use Scenario: Conditioning high-impedance mV-level output from glass pH electrodes in industrial process analyzers operating across −20°C to +85°C ambient. IC Role / Device Role / Timing Role: Unity-gain buffer with bootstrapped case (Pin 8) to isolate electrode from PCB leakage and maintain >10¹² Ω source impedance integrity. Use Value: 10¹⁵ Ω common-mode impedance and 15 μV/°C drift ensure stable pH reading accuracy (<0.01 pH unit error) over full military temperature range. |
| Electrometer Amplifier | Precision Integrator |
Use Scenario: Measuring ultra-low leakage currents (<100 fA) from insulating materials or vacuum chambers using guarded triaxial cabling and Teflon standoffs. IC Role / Device Role / Timing Role: Inverting configuration with guarded input (Figure 28) and 10¹⁴ Ω feedback resistor; case (Pin 8) tied to guard ring. Use Value: Guaranteed 75 fA bias current and 0.8 pF common-mode capacitance enable reliable integration of femtoampere currents over minutes without saturation. | Use Scenario: Building low-droop integrators for charge accumulation in radiation dosimetry or particle detection circuits requiring >100-second time constants. IC Role / Device Role / Timing Role: Op amp in integrator topology with polypropylene feedback capacitor and guarded input node to minimize dielectric absorption and leakage. Use Value: Sub-100 fA input bias current and laser-trimmed offset reduce integrator drift to <1 μV/s - supporting accurate charge-to-voltage conversion over extended periods. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar electrometer amplifier applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LMC662CMX/NOPB | CMOS input (2 fA typ), but only rated 0°C to +70°C; no MIL-STD-883B option; 1.3 MHz GBW, 1.5 V/μs slew rate. | Not suitable for −55°C to +125°C operation or high-reliability military/aerospace use; lacks guard pin and TO-99 hermeticity. | Select only for commercial-grade, cost-sensitive designs where extended temperature and screening are unnecessary. |
| ADA4530-1ARZ | Femtoampere input (20 fA max), integrated guard buffer, 2 MHz GBW, but requires dual ±5 V supply and has no TO-99 package. | Superior noise and integrated guarding, but incompatible with legacy TO-99 footprints and high-voltage ±15 V systems. | Prefer for new designs prioritizing lowest possible input current and ease of guarding; not drop-in for AD549SH/883B layouts. |
Compared with LMC662CMX/NOPB and ADA4530-1ARZ, AD549SH/883B uniquely combines MIL-STD-883B reliability, TO-99 hermetic packaging with dedicated guard pin, and guaranteed 75 fA bias current over full military temperature range - making it irreplaceable in legacy and high-assurance analog signal chains where footprint, screening, and extreme input impedance stability are mandatory.
Availability
AD549SH/883B is available at Aetrix Electronics and suitable for aerospace instrumentation, downhole oilfield sensors, and radiation monitoring systems requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for AD549SH/883B 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 AD549 series belongs to Analog Devices' precision electrometer op amp product line, engineered specifically for ultra-high-impedance, low-leakage signal conditioning in scientific instrumentation, analytical chemistry, and defense-grade sensor interfaces.
FAQ
What is the guaranteed input bias current specification for AD549SH/883B over temperature?
The AD549SH/883B guarantees a maximum input bias current of 75 fA at 25°C, with performance validated over the full military temperature range (−55°C to +125°C). At TMAX, bias current rises to 100 fA - still among the lowest available for hermetically packaged op amps. This value is 100% tested and specified per MIL-STD-883B, ensuring reliability in mission-critical applications where leakage must remain below 100 fA.
Does AD549SH/883B require external offset nulling, and how does it affect performance?
Yes, AD549SH/883B supports offset nulling via Pins 1 and 5 using a 10 kΩ potentiometer. When adjusted, it introduces ≤1.2 μV/°C additional drift (based on AD549K/L spec, applicable to S grade). For applications demanding ultimate dc stability, leaving the device unadjusted preserves its laser-trimmed 15 μV/°C max drift. Nulling is recommended only when initial offset exceeds system tolerance - and always performed after thermal stabilization.
How is the guard pin (Pin 8) used in AD549SH/883B, and why is it critical?
Pin 8 is internally connected to the TO-99 metal case and serves as the guard terminal. In inverting configurations, it must be tied to the guard ring surrounding the inverting input trace; in followers, it connects directly to the output. This bootstrapping reduces input node capacitance (typ. 0.8 pF) and blocks surface leakage paths - essential for preserving the 10¹⁵ Ω common-mode impedance and achieving sub-100 fA bias current in real-world PCB layouts.
Can AD549SH/883B operate from ±5 V supplies, and what are the trade-offs?
Yes, AD549SH/883B operates from ±5 V to ±18 V. At ±5 V, output swing reduces to ±3.5 V (vs. ±12 V at ±15 V), and open-loop gain drops to ~300 V/mV (from 1000 V/mV). Input bias current remains stable, but slew rate decreases to ~1.2 V/μs. Use ±5 V only when low-voltage operation is mandatory; for optimal electrometer performance - especially with high-value feedback resistors - ±15 V is strongly recommended.
Is AD549SH/883B pin-compatible with other TO-99 op amps, and what layout precautions apply?
AD549SH/883B is pin-compatible with standard FET-input and electrometer op amps in TO-99 (e.g., LM11, OPA128), but its guard pin (Pin 8) usage is unique and mandatory for performance. Layout must include Teflon standoffs, guarded input traces, and clean insulator surfaces - standard FR-4 is insufficient. Avoid conformal coating near inputs, and ensure all solder flux residues are fully removed to prevent surface leakage that would degrade the 75 fA input bias current of AD549SH/883B.
AD549SH/883B Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- TO-99-8 Metal Can
- Packaging:
- Tube
- Product Status:
- Active
- Amplifier Type:
- General Purpose
- Number of Circuits:
- 1
- Output Type:
- -
- Slew Rate:
- 3V/µs
- Gain Bandwidth Product:
- 1 MHz
- -3db Bandwidth:
- -
- Current - Input Bias:
- 0.075 pA
- Voltage - Input Offset:
- 300 µV
- Current - Supply:
- 600µA
- Current - Output / Channel:
- 20 mA
- Voltage - Supply Span (Min):
- 10 V
- Voltage - Supply Span (Max):
- 36 V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- Military
- Qualification:
- MIL-STD-883
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-99-8
AD549SH/883B FAQ
1.How can I place an order for AD549SH/883B through Aetrix?
Please submit a Request for Quotation (RFQ) for AD549SH/883B 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 AD549SH/883B reliable?
The price and inventory of AD549SH/883B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD549SH/883B is usually 5 days.
3.What payment methods are accepted for AD549SH/883B?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD549SH/883B transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD549SH/883B?
AD549SH/883B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD549SH/883B 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 AD549SH/883B?
For technical support, including AD549SH/883B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD549SH/883B requirements.
6.How does Aetrix verify that AD549SH/883B is sourced from the original manufacturer or authorized distributors?
All AD549SH/883B 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 AD549SH/883B meets industry standards.
7.What is the process for return or replacement of AD549SH/883B?
All AD549SH/883B units undergo pre-shipment inspection (PSI). If there is an issue with AD549SH/883B, 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 AD549SH/883B part is unused and in its original packaging.
Return procedure for AD549SH/883B:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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