AD549LH Analog Devices Integrated Circuit (Other) In Stock
AD549LH is an Analog Devices ultralow input bias current operational amplifier with a maximum bias current of 60 fA (0.06 pA) and 90 dB minimum CMRR, designed for electrometer and charge amplifier applications. It offers JFET input technology in a hermetic 8-pin TO-99 metal can package for precision scientific and instrumentation use.
- Manufacturer
- Analog Devices
- Package
- Other
- Pin Count
- 8
- Lifecycle
- OBSOLETE
- Datasheet
- AD549LH Datasheet PDF
- Category
- Integrated Circuit
- Temp Range
- ?°C to 70.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Ultralow input bias current of maximum 60 fA (6×10⁻¹⁴ A) enables accurate measurement of photodiode, ionization chamber, and electrometer-level signal sources
- 90 dB minimum common-mode rejection ratio (CMRR) ensures accurate differential signal amplification in high-noise laboratory and industrial measurement environments
- JFET input stage provides high input impedance exceeding 10¹⁵ Ω for virtually zero current loading on high-source-impedance transducers
- Hermetic TO-99 metal can package protects the die from humidity and contamination, critical for stable femtoampere-level bias current performance
- Low input offset voltage and drift enable precision DC measurements in charge amplifier and transimpedance amplifier topologies without periodic calibration
Applications
The AD549LH is the preferred operational amplifier for electrometer-grade instrumentation including pH meters, ion chromatography detectors, and Faraday cup charge collectors where the source impedance exceeds 10 GΩ and any input bias current causes unacceptable measurement error at the femtoampere level. Its ultralow 60 fA maximum bias current makes it the standard choice for transimpedance amplifiers measuring photodiode dark currents in optical spectrometers and nuclear particle detectors where signal currents are in the picoampere to femtoampere range. The device is also used in precision charge amplifiers for piezoelectric sensors in vibration measurement systems and scanning electron microscope (SEM) beam current monitors where charge accumulation over milliseconds must be detected without leakage from the amplifier input.
Specifications
| Source Url Status Check Date | 2013-05-01 14:56:13.031 |
| Pbfree Code | No |
| Manufacturer Package Code | H-08-1 |
| YTEOL | 0 |
| Amplifier Type | OPERATIONAL AMPLIFIER |
| Architecture | VOLTAGE-FEEDBACK |
| Average Bias Current-Max (IIB) | 6e-8 µA |
| Bias Current-Max (IIB) @25C | 6e-8 µA |
| Common-mode Reject Ratio-Min | 90dB |
| Common-mode Reject Ratio-Nom | 90dB |
| Frequency Compensation | YES |
| Input Offset Voltage-Max | 900 µV |
| JESD-30 Code | O-MBCY-W8 |
| JESD-609 Code | e0 |
| Low-Bias | YES |
| Low-Offset | YES |
| Micropower | NO |
| Neg Supply Voltage Limit-Max | -18 V |
| Neg Supply Voltage-Nom (Vsup) | -15 V |
| Number of Functions | 1 |
| Package Body Material | METAL |
| Package Equivalence Code | CAN8,.2 |
| Package Shape | ROUND |
| Package Style | CYLINDRICAL |
| Peak Reflow Temperature (Cel) | 260 |
| Power | NO |
| Programmable Power | NO |
| Qualification Status | Not Qualified |
| Slew Rate-Min | 2V/us |
| Slew Rate-Nom | 3V/us |
| Supply Current-Max | 0.7mA |
| Supply Voltage Limit-Max | 18V |
| Supply Voltage-Nom (Vsup) | 15V |
| Surface Mount | NO |
| Technology | BIPOLAR |
| Temperature Grade | COMMERCIAL |
| Terminal Finish | TIN LEAD |
| Terminal Form | WIRE |
| Terminal Position | BOTTOM |
| Time@Peak Reflow Temperature-Max (s) | 40 |
| Unity Gain BW-Nom | 1000 |
| Voltage Gain-Min | 100000 |
| Wideband | NO |
| Package | Other |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| Moisture Sensitivity Level | MSL 1 |
| ECCN | EAR99 |
| HTS Code | 8542.33.00.01 |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for AD549LH:
Frequently Asked Questions
What is the maximum input bias current of the AD549LH, and why is this critical for electrometer applications?
The AD549LH specifies a maximum input bias current of 60 fA (6×10⁻¹⁴ A) at 25°C, which is 1,000 times lower than typical JFET op-amps and 1,000,000 times lower than standard bipolar input op-amps. In electrometer applications measuring ionization chamber currents of 1 pA to 10 pA, a 60 fA bias current represents less than 6% systematic error, whereas a standard 1 nA bias current amplifier would completely overwhelm the 1 pA signal being measured.
What input impedance does the AD549LH provide, and how does it affect signal loading from high-source-impedance sensors?
The AD549LH JFET input stage provides a differential input impedance exceeding 10¹⁵ Ω (1 petaohm), which causes negligible signal loading even from source resistances of 1 GΩ to 100 GΩ typical of pH electrodes, piezoelectric transducers, and vacuum ionization chambers. At a 10 GΩ source resistance, the 60 fA maximum bias current creates only 0.6 mV of input offset error, whereas a 1 nA bias current amplifier would generate a 10 V error at the same source impedance, completely saturating the output.
What package does the AD549LH use, and why is a hermetic TO-99 can preferred over a plastic package for femtoampere-level circuits?
The AD549LH is housed in a hermetic TO-99 8-pin metal can package, which provides a moisture-proof sealed enclosure unlike plastic DIP or SOIC packages that allow humidity ingress over time. Even a small amount of moisture on the IC die or PCB traces creates leakage currents of tens of femtoamperes to picoamperes that directly add to the amplifier's measured input bias current; the hermetic TO-99 seal maintains the dry internal atmosphere needed to preserve the 60 fA bias specification over the device's full service life in laboratory environments.
What is the CMRR of the AD549LH, and in what measurement scenarios does this become the limiting factor?
The AD549LH specifies a minimum CMRR of 90 dB, meaning that a 1 V common-mode input swing (noise or ground bounce appearing equally on both inputs) produces less than 31.6 µV of differential error at the input. In single-ended electrochemical sensor measurements where the reference electrode floats and 50 Hz or 60 Hz mains interference couples equally to both signal and reference lines, the 90 dB CMRR attenuates the 1 V common-mode interference to 31 µV, preserving millivolt-level measurement accuracy in laboratory environments without extensive electromagnetic shielding.
How does the AD549LH compare to the OPA128 for a transimpedance amplifier measuring 10 fA photodiode dark current?
Both the AD549LH (60 fA max bias) and OPA128 (75 fA max bias) are suitable for 10 fA photodiode transimpedance applications, but the AD549LH's slightly lower 60 fA maximum bias current provides 25% less systematic offset current error when the source current is at the 10 fA signal level. At a 10 GΩ transimpedance gain resistor, the AD549LH maximum bias current generates 600 mV of output offset voltage versus the OPA128's 750 mV maximum, both requiring offset trim; the AD549LH hermetic TO-99 package also offers better long-term bias stability in high-humidity laboratory environments than the OPA128 plastic package.
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