Overview
The AD549KHZ is a monolithic electrometer operational amplifier produced by Analog Devices Inc. It is renowned for its ultralow input bias current, achieved through the proprietary Topgate™ JFET technology. This amplifier is designed for applications requiring very low input current and low input offset voltage. The AD549KHZ is particularly suited for use as a preamplifier for current output transducers such as photodiodes, photomultiplier tubes, and oxygen sensors. It also excels as a precision integrator or low droop sample-and-hold circuit. The device is available in a TO-99 hermetic package and is pin compatible with standard FET and electrometer op amps, making it an ideal choice for upgrading existing systems with minimal additional cost.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Input Bias Current | - | 60 fA | 200 fA | A |
| Input Offset Voltage | - | 0.5 mV (AD549K) | 1 mV (AD549J) | mV |
| Input Offset Voltage Drift | - | 15 μV/°C (AD549K) | 20 μV/°C (AD549J) | μV/°C |
| Supply Voltage | - | - | ±18 V | V |
| Unity Gain Bandwidth | 0.7 | 1.0 | - | MHz |
| Slew Rate | 2 | 3 | - | V/μs |
| Settling Time (0.1%) | 4.5 | - | - | μs |
| Operating Temperature Range | 0°C to +70°C (AD549J, AD549K, AD549L) | - | -55°C to +125°C (AD549S) | °C |
Key Features
- Ultralow Input Bias Current: Achieved through Topgate™ JFET technology, ensuring extremely low input current.
- Laser Trimmed Offset Voltage: Input offset voltage and drift are laser trimmed for precision performance, with values as low as 0.5 mV and 15 μV/°C.
- Low Quiescent Supply Current: A maximum quiescent supply current of 700 μA minimizes heating effects on input current and offset voltage.
- High Bandwidth and Slew Rate: Unity gain bandwidth of 1 MHz and a slew rate of 3 V/μs.
- Precision Integration and Sample-and-Hold: Excels as a precision integrator or low droop sample-and-hold circuit.
- Hermetic Packaging: Available in a TO-99 hermetic package, with the metal case connected to Pin 8 to minimize stray leakage.
Applications
- Preamplifier for Current Output Transducers: Ideal for photodiodes, photomultiplier tubes, and oxygen sensors due to its low input bias current.
- Precision Integration: Suitable for precision integration applications requiring low input current and offset voltage.
- Sample-and-Hold Circuits: Used in low droop sample-and-hold circuits where minimal drift is crucial.
- Electrometer Applications: Suited for electrometer applications requiring high precision and low input current.
Q & A
- What is the primary feature of the AD549KHZ operational amplifier?
The primary feature is its ultralow input bias current, achieved through Topgate™ JFET technology.
- What are the typical input offset voltage and drift values for the AD549K?
The typical input offset voltage is 0.5 mV, and the drift is 15 μV/°C.
- What is the maximum quiescent supply current of the AD549KHZ?
The maximum quiescent supply current is 700 μA.
- What is the unity gain bandwidth of the AD549KHZ?
The unity gain bandwidth is 1 MHz.
- What type of package is the AD549KHZ available in?
The AD549KHZ is available in a TO-99 hermetic package.
- What are some common applications of the AD549KHZ?
Common applications include preamplification for current output transducers, precision integration, and sample-and-hold circuits.
- What is the operating temperature range for the AD549KHZ?
The operating temperature range is 0°C to +70°C for the J, K, and L versions, and −55°C to +125°C for the S version.
- How is the metal case of the AD549KHZ connected?
The metal case is connected to Pin 8, allowing it to be independently connected to a point at the same potential as the input terminals.
- What is the slew rate of the AD549KHZ?
The slew rate is 3 V/μs.
- What is the settling time for a 10 V input step?
The settling time is 5 μs to 0.01%.
