Overview
The INA121UA/2K5G4, produced by Texas Instruments, is a FET-input, low-power instrumentation amplifier known for its excellent accuracy and versatility. This amplifier features a three-op amp design and is available in compact 8-pin DIP and SO-8 surface mount packages. It is designed to operate with very low quiescent current and offers a wide supply range, making it suitable for battery-operated and single 5V systems. The INA121 is laser-trimmed for low offset voltage, low offset drift, and high common-mode rejection, ensuring high precision in various applications.
Key Specifications
| Parameter | Conditions | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Input Offset Voltage, RTI | ±200 | ±200 | ±500 | µV | |
| Input Offset Drift | ±2 | ±2 | ±5 | µV/°C | |
| Input Noise | f = 1kHz, G = 100 | 20 | 20 | nV/√Hz | |
| Common-Mode Rejection | G = 100 | 96 | 106 | 90 | dB |
| Supply Range | ±2.25 | ±15 | ±18 | V | |
| Quiescent Current | ±450 | ±525 | µA | ||
| Temperature Range | –40 | 85 | °C | ||
| Bias Current | ±4 | pA | |||
| Safe Input Voltage | ±40 | V |
Key Features
- Low quiescent current: ±450µA
- Low input offset voltage: ±200µV
- Low input offset drift: ±2µV/°C
- High common-mode rejection: 106dB at G = 100
- Wide supply range: ±2.25V to ±18V
- Low nonlinearity error: 0.001% max
- Input protection to ±40V
- Gain adjustable from 1 to 10,000 with a single external resistor
- High impedance input: approximately 10^12 Ω
- Compact 8-pin DIP and SO-8 surface mount packages
Applications
- Low-level transducer amplifiers (bridge, RTD, thermocouple)
- Physiological amplifiers (ECG, EEG, EMG, respiratory)
- High impedance transducers
- Capacitive sensors
- Multi-channel data acquisition
- Portable, battery-operated systems
- General purpose instrumentation
Q & A
- What is the typical quiescent current of the INA121UA/2K5G4?
The typical quiescent current is ±450µA.
- What is the input offset voltage of the INA121UA/2K5G4?
The input offset voltage is ±200µV.
- How is the gain of the INA121UA/2K5G4 set?
The gain is set by connecting a single external resistor, RG, between pins 1 and 8.
- What is the common-mode rejection ratio (CMRR) of the INA121UA/2K5G4 at a gain of 100?
The CMRR is 106dB at G = 100.
- What is the safe input voltage range for the INA121UA/2K5G4?
The safe input voltage range is ±40V.
- What are the package options for the INA121UA/2K5G4?
The package options include 8-pin plastic DIP and SO-8 surface mount.
- What is the temperature range for the INA121UA/2K5G4?
The operating temperature range is –40°C to +85°C, and the storage temperature range is –55°C to +125°C.
- How does the INA121UA/2K5G4 handle high impedance sources?
The INA121UA/2K5G4 has low input bias current (±4pA), making it suitable for use with high impedance sources.
- What are some common applications of the INA121UA/2K5G4?
Common applications include low-level transducer amplifiers, physiological amplifiers, high impedance transducers, capacitive sensors, multi-channel data acquisition, and portable, battery-operated systems.
- How can the output offset voltage of the INA121UA/2K5G4 be trimmed?
The output offset voltage can be trimmed using an optional circuit that applies a voltage to the Ref terminal, which is summed at the output. An op amp buffer can be used to maintain low impedance on the Ref pin.
